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Moisture and Water Activity
... From the compositional data, shown in Table 2, it can be seen that beefsteak had 0% carbohydrates, and concentrated orange juice had approximately 37% carbohydrates. In the presence of carbohydrates water can form hydrates and decrease the available water for phase change (Park, 2008). This suggested that beefsteak had less bound water, so most of its water fraction had undergone phase change unlike concentrated orange juice which had high amount of soluble sugars (Park, 2008;Thanatuksorn, Kajiwara, Murase, & Franks, 2008). ...
... In the presence of carbohydrates water can form hydrates and decrease the available water for phase change (Park, 2008). This suggested that beefsteak had less bound water, so most of its water fraction had undergone phase change unlike concentrated orange juice which had high amount of soluble sugars (Park, 2008;Thanatuksorn, Kajiwara, Murase, & Franks, 2008). In the case of Danishes, no noticeable peak was observed; this may be due to its comparatively low moisture content (21% w.b.) (Hamdami et al., 2004b). ...
... Hence, the latent heat of phase change was assumed to be a constant for a particular food item. The latent heat of phase change and the bound water fraction, calculated from Eq. (4), for the four food items and one model food system, are given in Table 3. Calculated latent heat of phase change and bound water fraction for each food item, were in the range of values previously reported in the literature (Cengel, 2007;Park, 2008;Potter & Hotchkiss, 1998). As mentioned earlier Danishes did not show any phase change. ...
... Water activity of food product is a useful indicator of its susceptibility to degradation processes caused by the growth of microorganisms and the intensity of biochemical and chemical reactions [1,40,41]. It is particularly important when the food is intended for storage. ...
... Slightly lower value of 0.92 were reported for sous vide cooked pork loin by Díaz et al. [43]. Nevertheless, all values observed in our study were high and could not affect diversity in storage stability of investigated samples, particularly in terms of microbiological spoilage [40]. ...
Pork loin slices were sous vide cooked at 60 °C and 65 °C for 2 h, 3 h and 4 h, and at 70 °C and 75 °C for 1 h, 1.5 h and 2 h. The cooking loss of the meat samples significantly increased with the temperature and time of heat treatment, but no correlation between cooking loss and moisture content in the samples was noted. All samples showed similar pH and water activity values. Regarding colour parameters, only yellowness showed significant differences between the samples and was affected by the temperature and time of cooking. Texture profile analysis revealed the lowest hardness of the samples cooked at 60 °C. Sensory analysis showed that cooking at 60 or 65 °C for 4 h ensured the most acceptable sensory features of the investigated samples, and tenderness and juiciness influenced the overall acceptability in the highest degree. All samples were microbiologically safe for consumption.
... where m0 is the weight of sausage obtained after filling and mt is the weight of the sausages after a specific processing time (0, 6,11,18,30,45, and 120 days). The measurements of moisture were performed by air oven drying [6], while for the NaCl content, the method of Volhard (ISO 1841-2: 1996) was used [7]. ...
... where m0 is the weight of sausage obtained after filling and mt is the weight of the sausages after a specific processing time (0, 6,11,18,30,45, and 120 days). The measurements of moisture were performed by air oven drying [6], while for the NaCl content, the method of Volhard (ISO 1841-2: 1996) was used [7]. ...
The effect of two kinds of casings on the production and characteristics of a dry fermented sausage was investigated. In detail, an Italian product, naturally fermented at low temperatures and normally wrapped in beef casing instead of the most diffused hog one, was selected. Two different productions (one traditionally in beef casing (MCB) and another in hog casing (MCH)) were investigated over time to determine the differences particularly regarding proteolytic changes during fermentation and ripening. First of all, the product in hog casing required a longer ripening time, up to 120 days, instead of 45-50 days, because of the lower drying rate, while the microbial dynamics were not significantly modified. Conversely, the proteolysis showed a different evolution, being more pronounced, together with the biogenic amines content up to 341 mg/Kg instead of 265 mg/Kg for the traditional products. The latter products were instead characterized by higher quantities of total free amino acids, 3-methyl butanoic acid, 3-Methyl-1-butanal, and 2-Methylpropanal, enriching the final taste and aroma. The traditional product MCB also showed lower hardness and chewiness than MCH. The results highlight how the choice of casing has a relevant impact on the development of the final characteristics of fermented sausages.
... El pH se midió como indicador de la frescura de la carne con un potenciómentro (Beckman, Palo Alto, California) en las muestras crudas. El análisis de a a en muestras crudas se realizó a temperatura ambiente (18 °C) con un psicrómetro Aqualab (Decagon CX-1, Washington, DC) calibrado contra agua destilada (Park, 2009). La dureza y las pérdidas por cocción se analizaron en muestras asadas después de eliminar el tejido conectivo, para lo cual se cortaron piezas de carne cruda de 1.5 cm de espesor y se calentaron por 8 min a 82 °C (temperatura interna) en un asador precalentado a 130 °C. ...
... The pH was measured in raw samples as indicator of meat freshness with a potentiometer (Beckman, Palo Alto, California). In raw samples the a w was analyzed at room temperature (18 °C) with an Aqualab psicrometer (Decagon CX-1, Washington, DC) calibrated against distilled water (Park, 2009). Hardness and cooking losses were analyzed in roasted samples after eliminating connective tissue, for which pieces of raw meat 1.5 cm thick were cut and heated for 8 min at 82 °C (internal temperature) in a preheated roasting oven at 130 °C. ...
The consumption of some long chain polyunsaturated fatty acids (LCPUFA), in particular docosahexanoic (DHA), eicosapentanoic (EPA) and conjugated linoleic (CLA) acids is beneficial for human health, thus its incorporation to meat gives added value, but sensory characteristics could be altered, causing rejection by the consumer. The objective of the present study was to evaluate the effect of adding these three LCPUFA to pig diet on physiochemical and sensory meat quality. The experimental design was randomized blocks with the following treatments: T1) diet+CLA; T2) diet+DHA+EPA; T3) diet+DHA+EPA+CLA; T4) diet (control). The data were analyzed using ANOVA and principal component analysis (PCA). Means were compared with Tukey test (p <= 0.05). Thirty-two Pietrain x Landrace x York x Duroc castrated pigs were used in two fattening phases: 4 weeks of development and 4 weeks of finishing. They were then electroanesthetized and sacrificed. To carry out the physiochemical analyses (pH, water activity, hardness and cooking loss) and qualitative description (flavor, texture and aroma) samples were taken from the Longissimus dorsi muscle. Flavor and aroma of pork meat fed with LCPUFA was described as roasted, beef-like, and sheep-like, with soft and juicy texture, although less acceptable than the control. Roasted flavor, a desirable attribute in meats, decreased in samples obtained from pigs with diets including DHA and EPA, and fishy aroma and flavor were not detected.
... 5g of powder was dried in a vacuum oven at 40°C and 30kPa until there was no change in weight [11]. Moisture content was tested three time for every sample. ...
Agarwood essential oil is the essential oil extracted from the heartwood of agarwood trees ( Aquilaria sp.) after inoculation or natural infection of one of several fungal species. The essential oil is proved to carry antioxidant, antimicrobial and anti-stress activities. Microencapsulation of essential oil included emulsification of oil into maltodextrin solution and spray drying of emulsion at different levels of inlet temperature and compressed air pressure. Microencapsulation process was qualified based on following parameters including process’s microencapsulation yield, moisture content of powder, powder particle size, encapsulated oil’s composition, oil recovery and drying yield. Microencapsulation yield was affected by inlet temperature whereas drying yield changed as air pressure varied from 1.5 to 2.5 kgf/cm ² . Other parameters were impacted by both variables. Besides, oil composition changed at an acceptable degree after microencapsulation process, in which there were an increase in percentage and the presence of some components but the main components still remained in the encapsulated oil. Finally, the drying air temperature of 150 °C and air pressure of 2.5 kgf/cm ² were the best parameters to obtain both microencapsulation yield of 89.12% and drying yield of 79.00%.
... (Shiva et al., 2007), (Farouk, 2011). Nitrates and nitrites delay rancidity of meat products and have also antioxidant characteristics (Park, 2008), (Gassara et al., 2016). ...
The use of food additive nitrite as a curing agent is common in meat products, but its concentration in these products has raised the interest of researchers, because of the possible toxicity to humans. The aim of this study is to assess the nitrite concentration in meat products, which is highly used by all population groups in Kosovo.
Forty-four samples of meat products purchased in Kosovo markets were analyzed for residual nitrites using the spectrophotometric method that uses absorption in the visible part of spectra. The amount of residual nitrites was detected in 19 (43%) of the samples, which included beef and chicken sausages, chicken & beef salami as well as beef prosciutto samples. The nitrite residue ranged between 0.1 and 11.5 mg/kg and was below the limits on the concentration of nitrites in meat products established by EU regulation 1333/2008. Although these findings show that, the nitrite residue in the analyzed meat products is within the permitted limits, the highest presence of residual nitrite in industrial and low-cost meat products indicates a need for further assessments of consumers’ exposure to nitrites
... Raw chicken has an average moisture content of 75% [20]. The present results indicated that moisture content was lower after drying, ranging from an average of 16:93 ± 1:29% to 10:79 ± 1:83%. ...
We present the first report on the effect of graded levels of Moringa oleifera leaf meal (MOLM) (0, 0.25, and 0.5%) and fat (0, 10, and 15%) on fatty acid profile, lipid oxidation, and proximate composition of chicken droëwors. On triplicate samples of all treatments, proximate analysis was done, the total lipid was quantitatively extracted using chloroform and methanol in a ratio of 2 : 1, fatty acid profiles were determined, and thiobarbituric acid reactive substances (TBARS) were measured. The present study showed that droëwors manufactured with 0% fat inclusion had less fat and more protein than those made with 10% and 15% fat. All treatments contained a greater percentage of C18:1c9 (oleic) (30.95 to 32.65%) acid than other fatty acids and a higher proportion of unsaturated fatty acids than saturated. T9 (15% fat, 0.5% MOLM) had significantly ( P < 0.05 ) higher PUFAs than T1 (0% fat, 0% MOLM) and T4 (10% fat, 0% MOLM). Treatments with 0.5% MOLM had significantly lower TBARS values after drying (0.01-0.07 mg MDA/kg) than treatments with 0% and 2.5% MOLM (0.05–0.15 mg MDA/kg). Therefore, MOLM inclusion at 0.25 and 0.5% effectively decreased TBARS of chicken droëwors with up to 15% fat inclusion after 72 h of drying and 168 h of storage and is a potentially good source of natural antioxidants for this traditional dried sausage product.
... When animal carcasses enter rigor mortis, water is lost in the form of drip mainly from the cut ends of the meat (Offer & Trinick, 1983). Excessive drip in meat packaging is unsightly to consumers and is a negative determinant of meat quality (Cawthorn et al., 2018;Park, 2008), especially since excessive drip loss causes unappealing moisture accumulation in the packaging which may result in a drier and less tender cooked product (Bowker & Zhuang, 2013). Drip loss is a particularly important factor to consider due to its financial implications. ...
Although many efforts have been made to improve and control the eating quality of meat, there is still high variability in palatability, which may ultimately result in customer dissatisfaction. Beef meat is especially intricate to study since consumers have specific preferences for degrees of doneness. The degrees of doneness in beef is known to affect its physicochemical properties and have a subsequent effect on palatability. Nevertheless, an in‐depth investigation into the exact changes that occur with increasing internal end‐point temperatures of meat is yet to be explored. With researchers implementing various cooking methods and cooking conditions (i.e., sample preparation and internal end‐point temperatures), the results of studies are often impossible to compare. This review provides an overview of the various benefits and drawbacks of the cooking methods commonly used at home, in commercial enterprises, and research on meat. Furthermore, the physicochemical changes in meat with increasing degrees of doneness are discussed in detail with considerations of the subsequent changes in the sensory properties of meat.
... The chemical composition of meat is affected by both the muscle type and sex of the animals. Moisture content in meat is quantitatively the most important component, and is primarily dependent on the IMF content, but unaffected by the protein content, which is the second most abundant and nutritionally the most valuable component in lean meat, playing a central role in the mechanism of water binding and meat tenderization (Huff Lonergan, Zhang, & Lonergan, 2010;Park, 2008). Similarly, the present results show higher moisture contents in muscles with a low amount of IMF, and vice versa. ...
The histochemical characteristics, physical attributes, chemical composition, and sensory profile of three muscles (longissimus thoracis et lumborum – LTL, rectus abdominis – RA, triceps brachii – TB) from Fleckvieh (N = 24) bulls and heifers were compared. Samples of each muscle were taken within 1 h of slaughter to assess muscle fibre traits, while physio-chemical meat quality was assessed in each muscle at 48 h post mortem, followed by the sensory assessment of the muscles after 7 days of ageing. Despite identical raising conditions, bulls showed more favourable growth and slaughter performance, but heifers produced meat with more favourable sensory characteristics, as a result of a higher proportion of IIB fibres in their muscles, as well as a higher intramuscular fat content, and lower collagen content.
... Thermogravimetric analysis is able to work with both types of food samples. As a direct measurement of moisture, thermogravimetric analysis additional advantage consist on the fact that the method can be improved if data comparable to Karl Fisher is desired by distinguishing among bound and free water in food (Rückold et al., 2000;Park, 2009;Wang et al., 2017). ...
Method validation within food science is a not only paramount to assess method certainty and ensure results quality but a pennant in analytical chemistry. Proximate analysis is an indispensable requirement for food characterization. To improve proximate analysis, automated protein and thermogravimetric methods were validated according to international guidelines (including ISO 17095) and acceptance criteria of results based on certified reference materials and participation within international recognized proficiency schemes. Common food groups (including meat, dairy, and grain products) were included and at the end of validation, we obtained three rugged and accurate methods and z scores (−2 ≥ x ≤ 2) and recoveries (92–105%). During optimization, variables such as gas flows, subsample masses, and temperatures were varied and specific conditions (those that rendered the best results) were selected for each food group. For each validated method, a comparison (technical and economic) among the data obtained and the data extracted for its traditional counterpart were included: assays validated demonstrate to be more cost-effective labor-wise (ca. 9 and 16-fold) than their traditional alternatives. Specifically for combustion assay regression analysis (y = 0.9361x, y = 1.1001x, and y = 0.9739x, for meat, dairy and grain products, respectively) were performed to assess the factor, if any, which must be applied to the results to effectively match those obtained for Kjeldahl method. Finally, in the case of protein, samples can be analyzed under 5 min with no residue and a subsample mass below 400 mg. Moisture and ash analysis can be performed simultaneously using the same subsample. Data herein will also help harmonize and advance food analysis toward more efficient greener methods for proximate analysis.
... Moisture content is one of the most vital and widely used indices in processing foods, which has great economic value and quality of food products (Park, 2008). The fried samples were weighed then dried to a constant weight at 105°C using a moisture meter (MA35, Sartorius Co., Göttingen, Germany). ...
Squid are commercial marine species that have high nutritional value. This study aimed to compare the influences of vacuum frying and atmospheric frying on the physicochemical properties and protein oxidation of three main parts (ring, tentacle, and fin) of the squid Loligo chinensis. The results showed that the vacuum‐fried (VF) group had lower moisture and total fat contents and looser microstructures than the atmospheric‐fried (AF) group. The amino acid contents and molecular weight revealed that the proteins were well preserved during vacuum frying. Carbonyl content in the VF ring, tentacle, and fin samples increased nearly 2.53‐, 1.54‐, and 2.56‐fold, respectively, compared to that in the corresponding fresh group, but these increases were lower than those of the corresponding AF group. In addition, the secondary structures of proteins revealed a slight decrease in the α‐helix and β‐turn contents and a significant increase in the β‐sheet content during vacuum frying. Therefore, vacuum frying can be used as an efficient processing method to conserve the high nutritive quality of the product.
Practical Application
As a developing alternative technology to prepare healthier fried products, vacuum frying has been the focus of recent researches. Vacuum frying produced squid products that had lower TBARS values, carbonyl contents, and Schiff base substances compared to atmospheric frying. And the protein secondary structures of the vacuum‐fried group retained better. The study proved that vacuum frying could be an effective method with the advantages of high protein stability and product quality.
... 4 using oven drying method that could only measure an evaporated water [10]. According to Park [18] the evaporated water is composed of free-water and weakly-bound water molecules. It could therefore be assumed that the moisture content of meats highly depends on the types of water molecules in meats. ...
The study was conducted to evaluate the effect of formic acid and/or Saccharomyces cerevisiae on breast meat characteristics of the Indonesian indigenous crossbred chickens. A total of 200 day-old chicks were randomly distributed to four experimental groups (with five replications each), including T0 (chicks fed control diet), T1 (chicks fed diet supplemented with formic acid at 2g/kg), T2 (diet supplemented with S. cerevisiae at 3g/kg) and T3 (diet supplemented with formic acid at 2g/kg and S. cerevisiae at 3g/kg). At week 9, the chicks were slaughtered and from which the samples of breast meat were collected. Our results showed that total protein was higher ( p < 0.05) in breast meat of T3 than that in other groups. The moisture content and water holding capacity were lower ( p < 0.05) than that in other groups. The breast meat from T0 showed higher ( p < 0.05) L* (lightness) values than other meats. The fat content, pH, a* (redness) and b* (yellowness) values of meats were not substantially affected by the treatments. In conclusion, dietary supplementation of a combined mixture of formic acid and Saccharomyces cerevisiae was effective in improving the breast meat quality of the Indonesian indigenous crossbred chickens.
... where W o is the initial weight of the feed and feed materials, and M wb is the initial moisture content of the feed and feed materials in decimal calculated using Equation (1). The difference in weight of the wetted and dried feed and feed materials before addition of water and drying and the DM (Equation (2)) were used in computing the new moisture content. ...
The dry matter (DM) content of feed is vital in cattle nutrition and is inversely correlated with moisture content. The established ranges of moisture content serve as a marker for factors such as safe storage limit and DM intake. Rapid changes in moisture content necessitate rapid measurements. A rapid and non-destructive global model for the measurement of moisture content in total mixed ration feed and feed materials was developed. To achieve this, we varied and measured the moisture content in the feed and feed materials using standard methods and captured their images using a hyperspectral imaging (HSI) system in the spectral range of 1000-2500 nm. The spectral data from the samples were extracted and preprocessed using seven techniques and were used to develop a global model using partial least squares regression (PLSR) analysis. The range preprocessing technique had the best prediction accuracy (R2 = 0.98) and standard error of prediction (2.59%). Furthermore, the visual assessment of distribution in moisture content made possible by the generated PLSR-based moisture content mapped images could facilitate precise formulation. These applications of HSI, when used in commercial feed production, could help prevent feed spoilage and resultant health complications as well as underperformance of the animals from improper DM intake.
Fresh meat has a limited shelf life and is prone to spoilage. Drying serves as a common method for food preservation. Non-thermal techniques such as ultrasound treatment (US) can positively affect the drying processes and alter the final product. The study aimed to evaluate the impact of US pre-treatment on the hot air (HA) and freeze-drying (FD) of chicken breast meat and the quality of the dried products. US pre-treatment had a varied impact depending on the drying method used. The contact US method extended the HA drying time (about 50%) but improved water removal during FD (about 30%) compared to the untreated samples. Both methods resulted in low water content (<8.3%) and low water activity (<0.44). While rehydration properties (RR) and hygroscopicity (H) were not significantly affected by US pre-treatment in HA drying (about 1.35% and about 1.1, respectively), FD noticed differences due to shrinkage and porosity variations (RR: 2.4–3.2%, H: 1.19–1.25). The HA-dried samples exhibited notably greater tissue shrinkage and a darker surface color than the FD meat. Ultrasonic processing holds substantial potential in creating dried meat products with tailored characteristics. Hence, meticulous consideration of processing methods and parameters is of utmost importance.
Prolonged storage and long-distance transportation of green coffee beans exposes them to undesirable fluctuations in temperature (T) and relative humidity (r.h.), which can change the physical (wet-basis moisture content (MCwb), water activity (Aw), and color) and sensory characteristics of the coffee. High humidity also supports mold growth, decay, and microbial activities. Thus, the objective of this study was to evaluate the efficacy of commercially available desiccants for preserving the moisture content of green coffee between 10-12% MCwb, when stored in either hermetic packages and/or jute sacks, and to assess the corresponding impact on sensory quality. A conventional coffee storage and transportation period from Brazil to Italy with a duration of 42 days was mimicked in environmental chambers. Treatments in a 3 × 3 factorial design consisting of three packaging materials (GrainPro SuperGrain bag, GrainPro TranSafeliner, and/or jute sacks) and desiccants (Drying Beads®, CaCl2, or no desiccants) were evaluated. Additionally, four different mass ratios of green coffee to desiccant ranging from 50 to 300 – g coffee per g desiccant were also evaluated. The MCwb, Aw, and color of all samples were measured approximately weekly over 42 days. In comparison to the control (no desiccant, and only jute sacks), we observed a statistically significant impact for all tested desiccants and hermetic packages for maintaining the proper MCwb, Aw, and color. No significant difference was observed for the different desiccant masses tested when they were placed inside the hermetic packaging, but the desiccants were ineffective without the hermetic packaging. Triangle test and descriptive sensory evaluation yielded no significant differences between the use of hermetic packages with or without desiccants.
Preserving fresh food, such as meat, is significant in the effort of combating global food scarcity. Meat drying is a common way of preserving meat with a rich history in many cultures around the globe. In modern days, dried meat has become a well enjoyed food product in the market because of its long shelf-life, taste and health benefits. This review aims to compile information on how the types of meat, ingredients and the used drying technologies influence the characteristics of dried meat in physicochemical, microbial, biochemical and safety features along with technological future prospects in the dried meat industry. The quality of dried meat can be influenced by a variety of factors, including its production conditions and the major biochemical changes that occur throughout the drying process, which are also discussed in this review. Additionally, the sensory attributes of dried meat are also reviewed, whereby the texture of meat and the preference of the market are emphasized. There are other aspects and concerning issues that are suggested for future studies. It is well-known that reducing the water content in meat helps in preventing microbial growth, which in turn prevents the presence of harmful substances in meat. However, drying the meat can change the characteristics of the meat itself, making consumers concerned on whether dried meat is safe to be consumed on a regular basis. It is important to consider the role of microbial enzymes and microbes in the preservation of their flavor when discussing dried meats and dried meat products. The sensory, microbiological, and safety elements of dried meat are also affected by these distinctive changes, which revolve around customer preferences and health concerns, particularly how drying is efficient in eliminating/reducing hazardous bacteria from the fish. Interestingly, some studies have concentrated on increasing the efficiency of dried meat production to produce a safer range of dried meat products with less effort and time. This review compiled important information from all available online research databases. This review may help the food sector in improving the efficiency and safety of meat drying, reducing food waste, while maintaining the quality and nutritional content of dried meat.
The oldest preservation techniques used are drying techniques, which are employed to remove moisture and prevent microorganisms’ growths, prolonging a material’s shelf life. This study evaluates the effects of drying methods on carboxymethyl cellulose (CMC) + citric acid (CA) coating layers on cotton threads. For this reason, cotton threads were washed and then coated with different layers of CMC cross-linked with CA, followed by drying using an oven (OD), infrared (IR), and a combination of oven + IR (OIR) drying methods at 65 °C. Our investigations revealed that CMC + CA yields a pliable biopolymer. The differences in drying regimes and coating layers of CMC + CA have a significant effect on the coated cotton thread strength and absorption capability. The study concluded that the IR drying regime is more effective to dry a single-layered cotton thread with a single layer of CMC + CA coating to enhance desirable properties for wound dressing modification.
Jackfruit (Artocarpus heterophyllus Lam.) and snake fruit [Salacca zalacca (Gaert.) Voss] are tropical fruits that are rich in vitamins and minerals. Due to their specific aroma and unique taste, jackfruit and snake fruit have great potential to be processed into dried fruits and healthy snacks. In this work, jackfruit and snake fruit were freeze-dried using a self-designed laboratory-scale freeze dryer. The freeze dryer was constructed with a stainless-steel plate (3 mm thickness). The drying rates were determined with three different heating temperatures: 50, 60, and 70ºC. This study also investigated the effect of the freeze-drying process on the characteristics of dried fruit such as moisture content, texture, color, ascorbic acid content, and morphological of dried samples. Results showed that the heating temperatures were revealed to affect characteristics such as drying rate, final moisture content, texture, and ascorbic acid content. Increased drying rate and decreased drying time were observed with an increase in the dryer temperature. The sample resulted from 70ºC of heating temperature exhibited the optimum results in terms of hardness and ascorbic content preservation. The first-order kinetic model was the best fit for the prediction of drying kinetics of all materials.
The objective was to estimate quality changes in Chilean sea cucumber (Athyonidium chilensis) using sun drying (SD), freeze‐drying (FD), and combined electrohydrodynamic and FD (EHD‐FD) at 30°C, packaged in low‐density polyethylene packages and stored at 30%, 50%, 70%, and 90% relative humidity (RH) for 3 mo. Water activity (Aw) content, moisture content (MC), total volatile base nitrogen (TVBN), hardness, and springiness were monitored. The Weibull model was applied to determine kinetics and predict shelf life. Initially, SD exhibited lower quality. All indicators increased over time at 70% and 90% RH, regardless of the drying treatment. The Weibull model was well fitted with all TVBN data, the indicator selected for shelf life. The shortest shelf life during storage was for SD. As for FD and EHD‐FD, the most important difference occurred at 50% RH with 52 and 44 days, respectively. Chilean sea cucumber (A. chilensis) has a high nutritional value. Its properties are reduced when it is sun‐dried. Therefore, other drying methods such as freeze‐drying and electrohydrodynamics as pretreatment combined with freeze‐drying are used to improve its quality and nutritional parameters and durability. The study of accelerated shelf life at different levels of relative humidity of Chilean sea cucumber offers tools for producers given that the Weibull model can predict the durability of the product and the preservation conditions of dry products over time.
The study examined the effect of drying compartment and maltodextrin concentration on the functional properties of Bambara groundnut milk powder (BGNMP). Bambara groundnut milk (BGNM) was prepared from Bambara groundnut (BGN) flour and water, further processed into BGNM and dried using the spray drying process. Total solids of BGNM were increased with 5, 10, and 15% of maltodextrin. Functional properties of BGNMP were analyzed. Water absorption indices (WAI), wettability, and water solubility indices (WSI) ranged from 0.19 to 0.45 g/g, 136.8 to 292.4 s, and 85.18 to 90.25%, respectively. BGNMP (10%) was significantly (p < .05) higher in WSI (88.80%) compared to BGNMP with 5% maltodextrin. BGNMP (10%) was significantly higher (p < .05) in WAI (0.40 g/g) compared to BGNMP with 15% maltodextrin. BGNMP samples color characteristics were significantly (p < .05) different with an acceptable color difference (ΔE). BGNMP (10%) had acceptable hydration properties over BGNMP (5%, 15%).
Moisture determination is one of the most important and most widely used measurements in the processing and testing of foods. Since the amount of dry matter in a food is inversely related to the amount of moisture it contains, moisture content is of direct economic importance to the processor and the consumer. Of even greater significance, however, is the effect of moisture on the stability and quality of foods. Grain that contains too much water is subject to rapid deterioration from mold growth, heating, insect damage, and sprouting. The rate of browning of dehydrated vegetables and fruits and of oxygen absorption by egg powders increases with an increase in moisture content.
The interest in water binding lies in several food and health areas such as:
1.
Selection of water binding ingredients for intermediate moisture foods where the optimization is towards high water content with good stability (71).
2.
Selection of ingredient or process modifications to maximize functionality and handling of cereal doughs in process equipment such as extruders (56).
3.
Selection of ingredients or process steps to maximize water content while maintaining stability and crispness in dried cereal products (8, 72, 82).
4.
Ingredient modification or selection for use in gels and meat/ fish emulsions to minimize water loss and maximize juiciness (for example, substituting water-humectant for fat to make reduced calorie meat sausage, (45, 57, 78).
5.
Selection of fiber type to use in food systems that would increase gut water binding and thus aid in prevention and/or cure of certain diseases such as cancer or diverticulosis (10, 34, 60).
6.
Characterization of the water binding in diseased, damaged and/or tumor tissues as compared to normal tissues (17, 67, 68).
7.
Characterization and selection of ingredients to maximize tableting ability in dry pharmaceuticals (9).
8.
Characterization and selection of ingredients to maximize flowability and dispersibility of dry powders (54).
9.
Selection of cryoprotectants for the freezing and preservation of live cells and tissues (14, 21).
A literature survey revealed that the apparent value for the moisture content of a malt depended on the method used to determine it. This was confirmed by a comparison of four methods: (a) the Institute of Brewing Standard Method; (b) drying in vacuo; (c) Karl Fischer titration; and (d) distillation with toluene in the Dean & Stark apparatus. It was found that results obtained by methods (b), (c) and (d) were in satisfactory agreement, but that results for the Institute Standard Method were substantially lower. This is considered to be due to a chemical reation occurring during oven-drying, the most likely reaction being partial enzymic hydrolysis of starch or protein. The principle of differential thermal analysis was applied to demonstrate the occurrence of a chemical reaction under the conditions pertaining to oven-drying.
Freezing point depression of milks of various concentrations (i.e. 0–35 wt %) were measured by the thermistor cryoscope method. The method was initially validated using aqueous NaCl and sucrose solutions at high concentrations as their data are readily available in literature. The effect of fat content on freezing point depression of milk was found to be minimal. Effective molecular weights were calculated based on existing semi-empirical thermodynamic relationships. The effect of aging of skim milk at high concentrations on freezing point depression was also observed and the quantitative results are reported here.
Six studies were to determine effects of drying method, stage of maturity, freezing and thawing, and five agronomic variables on carotene contents of forages and to evaluate near infrared reflectance spectroscopy for predicting carotene content in baled alfalfa hay. Microwave dried samples had the highest carotene among all drying methods tested. As drying time increased, carotene decreased. Storage in a refrigerator at 2°C for 3 to 4 wk reduced carotene. The higher the ini- tial carotene, the greater was the decrease. Thawing caused the most degradation of carotene, with the reduction continuing as thawing time was extended. Carotene contents were not changed if fresh sampled were frozen or refrigerated for 24 h or held for 4 h at room temperature and light. Carotene was affected by species, light, nitrogen fertilization, and interaction of light x nitrogen fertiliza- tion. Prediction equations by infrared reflectance with correlations were de- veloped for carotene. Correlations tended to increase if samples were from the same sources and preparation methods. The microwave-dried samples did not fit the equation when combined with samples from other methods. Seventy-eight call-
The efficiency of 21 chemicals as drying agents for gases has been determined by collecting the residual water in a liquid nitrogen trap and weighing. The best of the desiccants tested and the residual water in micrograms per liter of gas are: anhydrous magnesium perchlorate (0.2), barium oxide (2.8), alumina (2.9), phosphorus pentoxide (3.6), and Molecular Sieve 5A (3.9).
The water-binding properties of four gelling macromolecules (carrageenan, agar, potato starch and gelatin) were studied through measurement of the vapor pressure of water in the gels, suction pressure and Flory-Huggins x-value developed by the gel, and reduced mobility of water protons as measured by the spin lattice relaxation time from NMR. The difference in water binding between gels could be explained based on hydrogen bonding of water to specific sites and between water molecules; induced water-water interactions due to hydrophobic regions on the macromolecule; and dipole interactions of water with the ionic sites on the macromolecule. The suction pressure method shows carrageenan and agar to be the best water binders at low concentrations which is illustrated by a decreased x-value with increased concentration. Gelatin and starch show opposite behavior. The NMR results indicate a different order of water binding due to the difference in cooperative bonding. In this case agar was the best water binder at low aw and gelatin the poorest. This study shows the difficulty that could arise in using only one index of water binding.
Moisture assays can be one of the most important analyses performed on a food product and yet one of the most difficult from
which to obtain accurate and precise data. This chapter describes various methods for moisture analysis – their principles,
procedures, applications, cautions, advantages, and disadvantages. Water activity measurement also is described, since it
parallels the measurement of total moisture as an important stability and quality factor. With an understanding of techniques
described, one can apply appropriate moisture analyses to a wide variety of food products.
The scientific literature published since Pande's comprehensive monograph Handbook of Moisture Determination and Control (1974) was surveyed (to mid-1984) for new or improved techniques of determining moisture in solids. Particular attention is given to methods that might distinguish between bound and free moisture in organic solids. The classification of moisture is discussed, as well as pitfalls in sampling, in sample handling, and in the comparison of different methods. Six methods that show promise of being able to distinguish between bound and free moisture were identified: dynamic dielectric thermal analysis, coherent microwave measurements, infrared spectrometry, near-infrared reflectance spectrometry, thermal methods and nuclear magnetic resonance spectrometry.
This manual explains water activity in foods and shows why commonly held ideas about free and bound water are often inaccurate. It demonstrates how moisture sorption isotherms are created and how they are used to solve real-world problems such as the change in rate of moisture gain for individual packaged products over time, or the amount of sugar needed to lower the water activity of a product to make it shelf stable. The authors emphasize the physical chemistry of water in biological systems. For every equation provided they furnish examples from practical experience. These examples will help food scientists understand thermodynamics (equilibrium processes and water activity), dynamics (rate processes such as mass transfer of moisture between ingredients), and structure (weeping, swelling, droplets, and edible barriers). Using this manual will help solve product development problems and improve the quality of the foods brought to the market.
An ultrasonic technique has been developed for measuring the composition of chicken meat. The relationship between the composition and ultrasonic velocity of chicken meat was determined using chicken analogues of different composition, prepared from dried chicken powder, corn oil, and distilled water. The ultrasonic velocity of chicken analogues was measured at temperatures from 5 to 35 degrees C using an ultrasonic spectrometer. The ultrasonic velocity increased with solids-nonfat (SNF) content at all temperatures but had a more complex dependence on fat content. Around 15 degrees C the ultrasonic velocity was independent of fat content; however, at lower temperatures it increased with fat content, and at higher temperatures it decreased. Semiempirical equations were developed to describe the relationship between ultrasonic velocity and chicken composition. To determine the usefulness of these equations, the ultrasonic velocities of various chicken meats were measured. The compositions of the chicken meats predicted on the basis of ultrasonic measurements were in good agreement with those determined by using standard methods (r(2) > 0. 97). The ultrasonic technique could also be used to measure the solid fat content of chicken fat. This study shows that ultrasonic velocity measurements can be used to characterize chicken composition. This method has great potential for application in the food industry because it is simple, fast, nondestructive, and reliable.
Coulometric determination of moisture in polymers
- R L Hassel
Hassel, R.L. 1976. Coulometric determination of moisture in polymers. Am. Lab. 8:33-37.
Rapid methods for determination of fat and moisture content in meat products
- C W Everson
- T Keyahian
- D M Doty
Everson, C.W., T. Keyahian and D.M. Doty. 1955. Rapid methods for determination of fat and
moisture content in meat products. Amer. Meat Inst. Found. 26, Washington.
Properties of Ordinary Water Substance in all its Phases: Water Vapor, Water and All the Ices
- N E Dorsey
Dorsey, N.E. 1950. Properties of Ordinary Water Substance in all its Phases: Water Vapor, Water and All
the Ices, 2nd ed. Reinhold, New York.
Water and ice Food Chemistry
- O R Fennema
Fennema, O.R. 1996. Water and ice. In Fennema, O.R. (ed.), Food Chemistry. 3rd ed. Marcel Dekker,
New York, pp. 17–94.
Fundamental Aspects of the Dehydration of Foodstuff s
- J Kuprainoff
Kuprainoff, J. 1958. Fundamental Aspects of the Dehydration of Foodstuff s. Macmillan, New York, p. 14.
Handbook of Chemistry and Physics
- R C Weast
Weast, R.C. 1972. Handbook of Chemistry and Physics. 53rd ed. Chemical Rubber, Cleveland, OH.
A new method for the analytical determination of the water content of liquids and solids
- K Fischer
Fischer, K. 1935. A new method for the analytical determination of the water content of liquids and
solids. Angew. Chem. 48:394-396.
- National Research
- Council
National Research Council. 1928. International Critical Tables. Vol. 3. McGraw-Hill, New York,
p. 385.
Th ermogravimetry in food technology
- S M Dyszel
Dyszel. S.M. 1990. Th ermogravimetry in food technology. In Harwalkar, V.R. and C.Y. Ma, (eds.).
Th ermal Analysis of Foods. Elsevier, London, pp. 333-357.
Rapid Methods for Analysis of Food and Food Raw Material
- K H Torkler
Torkler, K.H. 1990. Rapid determination equipment for food quality control. In Baltes, W. (ed.).
Rapid Methods for Analysis of Food and Food Raw Material. Technomic Publishing, Lancaster, PA,
pp. 59-71.
A study on predicting carotene, nitrate, soluble N and fi brous fractions in forages and vegetables with near-infrared-refl ectance spectroscopy, and eff ects of processing methods on carotene contents
- Y W Park
Park, Y.W. 1981. A study on predicting carotene, nitrate, soluble N and fi brous fractions in
forages and vegetables with near-infrared-refl ectance spectroscopy, and eff ects of processing methods
on carotene contents. Ph.D. Dissertation, Utah State University, Logan, UT.
Refl ectance spectroscopy
- K H Norris
Norris, K.H. 1984. Refl ectance spectroscopy. In Stewart, K.K. and J.R. Whitaker, (eds.), Modern
Methods of Food Analysis. AVI Publishing, Westport, CT, pp. 167-186.
Determination of moisture in Canadian grain by electric moisture meter
- V Martens
- I Hlynka
Martens, V. and I. Hlynka. 1965. Determination of moisture in Canadian grain by electric moisture
meter. In Wexler, A. (ed.), Humidity and Moisture, Measurement and Control in Science and Industry.
Vol. 4. Van Nostrand-Reinhold, New York, pp. 125-133.
- A Pande
Pande, A. 1974. Handbook of Moisture Determination and Control. Vol. 1, Marcel Dekker, New York,
p. 1.
Laboratory techniques
- D Pearson
Pearson, D 1973. Laboratory techniques. In Food Analysis. Wiley, New York, pp. 27-59.
Effi ciency of chemical desiccants
- F Trusell
- H Diehl
Trusell, F. and H. Diehl. 1963. Effi ciency of chemical desiccants. Anal. Chem. 35:674-677.