Article

PH—Postharvest Technology: Surface Gloss and Weight of Eggplant during Storage

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Abstract

Surface gloss and weight loss are two important parameters to judge the freshness of eggplant. Data were collected in order to develop some quick and reliable instrumental methods to determine these. Surface gloss and weight loss of eggplant stored for 0–96 h at 80–84% relative humidity and 20°C temperature were determined using a computerized spectral radiometer and a precision electronic balance, respectively. The surface gloss was quantified in terms of gloss index, and a relationship between weight and gloss index during storage of eggplant was established. Gloss index and weight both decreased quadratically with storage period. Major changes were observed in the first 48 h of storage. Weight and gloss index of eggplant during storage were found to be correlated linearly.

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... There are a number of factors which influence the radiation and exact color that one perceives. Jha et al. had developed a spectral radiometer that is used in determining the freshness of the eggplant based on the surface gloss and the weight at the time of storage [162]. The Table 13.6 reports various studies regarding the non-destructive techniques implemented in vegetables [79]. ...
Chapter
Food safety and quality are of utmost importance for consumers, suppliers, and regulators. The methodologies for determining the food quality are majorly classified as destructive and non-destructive techniques. The destructive techniques used for determining the food quality are labor-intensive, time-consuming, cost-intensive, and biased, while non-destructive techniques are gaining popularity due to ease of operation, reliability, and real-time results. Non-destructive methods play an important role in food industries due to its inherent nature. Both external and internal quality can be determined by non-destructive methods and rapidly help in sorting the superior quality of food products. Currently, different non-destructive methods such as electromagnetic, optical, mechanical, and dynamic are gaining popularity due to ease of operation, reliability, and faster turnover. The major drawback of non-destructive methods is the high equipment cost and the use of various instruments to analyze various parameters. But even then, these methods help to ensure customer satisfaction of products as it helps in providing good quality products without rupturing it. This chapter gives broader concept of non-destructive method used in quality assessment of food products and their applications for food evaluation and quality.
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... Attempts to include the spectral information of the reflected light have been also made. Jha et al. used a spectroradiometer to record the light reflected by the curved surface of eggplants illuminated by a halogen light source (Jha, Matsuoka, et al. 2002). The ratio between reflected and incident light at each wavelength was used to define a spectral gloss index which, when integrated in the visible range, gave the gloss index of the sample. ...
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Factors affecting the composition, quality and storage life of fresh tomatoes (Lycopersicon esculentum Mill.), peppers (Capsicum annuum L.) and eggplants (Solanum melongena L.) as well as fresh-cut (minimally processed) produce are discussed both in the light of European Union (EU) quality standards and on the basis of recent research findings. The fruit of all three Solanaceous species are highly perishable and careful manipulation of the storage conditions is required in order to preserve quality at an acceptable level. The stage of harvest and the storage techniques applied relate largely to the climacteric or non-climacteric nature of the fruit, and the role of ethylene in fruit ripening is discussed. Tomato, pepper and eggplant fruit are all rich sources of antioxidants, and these substances are implicated in the prevention of cardiovascular and other human diseases. Apart from epidemiological studies on the relationship between antioxidant intake and disease occurrence, several studies have concentrated on the changes in antioxidant levels during fruit growth and maturation, as well as on the fate of antioxidants during storage and processing. The fruit of all three species are susceptible to chilling injury and this susceptibility restricts the temperature at which storage can be carried out. However, a number of studies have indicated the beneficial effects of enclosing fruit in plastic film of specific gas permeability. Because of the increasing demand for fresh-cut (minimally processed) salads, research has been directed at studying the behaviour of fresh-cut produce (e.g. pepper rings, cut tomato salads) during storage and marketing. Because of the increased perishability of fresh-cut produce and the danger of microbial activity, stringent packaging and storage techniques must be applied. This review is concluded with a brief consideration of future research perspectives.
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Eggplant genotypes of white, green and violet are very popular in the specific regions of sub-tropics and tropics. These possess enormous health benefits as having high antioxidant activity. Due to limited shelf life i.e. 3 days at ambient storage, wholesalers and retailers apply many unhygienic practices. They use petroleum based oil to make the fruit surface shiny and attractive. In the present study, Eggplant genotypes, viz. violet, green and white, were assessed after carnauba wax (CW) emulsion containing additives such as 2.5% polyethylene glycol (PEG) and 0.5% sodium alginate (SA) as T1, 0.5% SA as T2, 2.5% PEG as T3 and non-coated eggplant fruits as control fruits (T4) for shelf life extension and retention of nutritional quality attributes at ambient condition (20 ± 2 °C and RH 52–54%) for 7 days. The additives mixed CW coatings were effective in extending the shelf life and retaining the nutritional quality attributes than control genotypes. Sodium alginate (SA) mixed CW coating resulted in maximum shelf life extension of white eggplant genotypes by 7 days as compared to 3–4 days in control eggplant genotypes at ambient storage. However, 6.9%, 1.83% and 6.04% decrease in physiological loss in weight was obtained in 0.5% SA based CW coating after 5 days of ambient storage of violet, green and white eggplant genotypes, respectively in comparison to fully control eggplant genotype. The firmness level of eggplant genotypes in 0.5% SA based CW coating was more (85.1%, 50% and 45%) after 7 days of ambient storage of violet, green and white genotypes, respectively in comparison to fully control eggplant genotype. Similarly, total phenol content was also increased (26.1%, 37.5% and 180.9%) in 0.5% SA based CW coated eggplant genotypes of violet, green and white, respectively after 7 days of ambient storage in comparison to fully control eggplant genotype. Initially there had been increase in antioxidant activity in white genotype up to 5 days of storage which thereafter decreased on 7 days of storage in all the treatments. However, violet and green genotypes had not followed any trend during storage.
Article
Physiological disorders in harvested eggplant (Solanum melongena L.) fruit result in quality deterioration, short postharvest life and significant economic losses. In this study, the effects of methyl jasmonate (MeJA) on senescence in eggplant fruit were investigated. The results indicated that, compared to control, MeJA at 5 μM depressed ethylene production and effectively delayed fruit senescence. MeJA treatment was beneficial for maintaining fruit quality during storage, inhibiting increase of the calyx browning and weight loss, and retarding decline of sensorial quality, firmness and the anthocyanin content in peel. Moreover, MeJA effectively reduced the total phenolics content and the activity of the polyphenol oxidase (PPO) in calyx and pulp. MeJA also inhibited relative gene expression of PPO in pulp. The activities and gene expression of peroxidase and catalase were significantly induced by MeJA treatment. These findings indicate that the delayed senescence in eggplant fruit by MeJA is related with the decrease of enzymes associated with phenolics metabolism and antioxidant system. Our results suggest that MeJA has potential effect on maintaining the quality and extending postharvest life of eggplant fruit.
Article
This research was designed to develop and test an automatic image analysis method (algorithm) to classify CT images obtained from 1233 carrot (Daucus carota L.) sections (samples), collected during the 2013 and 2014 harvesting seasons. Classification accuracy was evaluated by comparing the classes obtained using eighteen CT images per carrot section to their undesirable fibrous tissue class, based on the industry-simulated invasive quality assessment (% of fiber). Class-0 represents fibrous-free samples, and class-1 denotes samples containing fibrous tissue. After CT image preprocessing, cropping, and segmentation, 3762 grayscale intensity and textural features were extracted from the eighteen CT images per sample. A 4-fold cross-validation linear discriminant classifier with a performance accuracy of 87.9% was developed using 95 relevant features, which were selected using a sequential forward selection algorithm with the Fisher discriminant objective function. This objective method is accurate in determining the presence of undesirable fibrous tissue in pre-processed carrots.
Article
This research was devised to evaluate Computed Tomography (CT) for asparagus fibrousness detection and more specifically develop and test an automatic image analysis method (algorithm) to classify CT images obtained from 859 asparagus (Asparagus officinalis L.) segment (samples), collected during two harvesting seasons (2014 and 2015). Classification accuracy was calculated by comparing the classes obtained using a combination of imaging, image processing, feature extraction, and classification schemes per asparagus segment against an industry-simulated invasive quality assessment. Grayscale intensity and textural features, 3762 total, were extracted from minimum and maximum resultant images from three CT planer views. A 4-fold cross-validation linear discriminant classifier with a performance accuracy of 91.2% was developed using 75 relevant features, which were selected using a sequential forward selection algorithm with the Fisher discriminant objective function. This objective method is accurate in determining the presence of tough-fibrous tissue in asparagus, which demonstrates a potential for such technology to objectively forecast asparagus quality and thus supports the asparagus industry through optimizing consumer acceptability and product utilization.
Article
Full-text available
Gloss measurements are used to evaluate the quality and appearance of a product, especially in cases where esthetic appearance is of importance. Most commercial glossmeters are designed for measuring products of flat surface and therefore are not suitable for food products because of their uneven, curved surface. A new generation of commercial glossmeters is recently available for confined areas, curved surfaces, and surfaces that are not uniform. This article provides a brief review of gloss measurement principles and methods for fresh fruits and vegetables. It reports on the gloss measurement of apples and other fresh products using a commercial glossmeter and a specially designed spectrometer-based gloss measurement prototype integrated with imaging and automatic sample positioning capabilities. Results showed that the prototype had a nonlinear relationship with standard gloss measurements. With the new setup, the gloss of apples was measured with the repeatability for 90% of the measurements being better than 16%, calculated as the ratio of the difference between maximum and minimum gloss values to the mean value in percent. Further research is needed to simplify the imaging/mechanical configuration and improve the coordinate calculation algorithm to achieve more accurate, repeatable gloss measurements.
Article
Full-text available
Bulk density, true density, angle of repose, coefficient of friction on metal surfaces, specific heat, thermal diffusivity and conductivity of gorgon nut were determined using standard techniques for different sizes of nuts at moisture contents and temperatures ranging from 15 to 60% (dry basis) and 25 to 55C, respectively. the physical properties varied quadratically with moisture content. Specific heat increased with moisture and temperature but decreased with the size of the nut; whereas, the thermal diffusivity showed a reverse trend. Thermal conductivity increased with moisture content but did not follow any trend with temperature within the range of the study. the physical and thermal properties data at various moisture contents and temperatures were used to develop equations for different sizes of gorgon nuts.
Article
Full-text available
Gorgon nuts are processed for their kernels in expanded form and this is known as makhana in India. Operations involved in the traditional method of processing make it laborious, time consuming and costly. This paper reports an investigation into the effect of five combinations of operations on recovery of makhana, viz., (1) roasting and popping; (2) drying, roasting and popping; (3) drying, tempering, roasting and popping; (4) first roasting, tempering, second roasting and popping; and (5) drying, first roasting, tempering, second roasting and popping. The design of the experiments was based on response surface methodology and they were conducted using thin-layer drying and a manual roasting method.The best combination of operations,based on the recovery of grade 1 makhana, was found to be number 5 above, that is, drying, first roasting, tempering, second roasting and popping. The data was analysed to find the optimum processing conditions, to give 97% grade 1 makhana. These were found to be a combination of first roasting of dried nut (moisture content 33% d.b.) at 335°C for 3·9 min, tempering for 23 h and second roasting at 335°C for 2·8 min. These conditions reduced the processing time to less than one-half as compared with the traditional method.
Article
A high-density spectrophotometer with fiber optic attachment was used to study the light transmittance through different regions of green tomatoes. The average of transmittance readings taken at four locations around the fruit was found to correlate with the maturity of the fruit. The correlations between optical criteria and the maturity of four varieties of tomatoes are given.
Article
Consumers are now more conscious about quality and source of their foods. Attempts made to determine the quality of food materials are numerous, but most of them are destructive in nature. In recent years, nondestructive methods of quality evaluation have gained momentum and a considerable attempts have been made to develop them. This paper reviews application of these non-destructive methods: magnetic resonance imaging, x-ray computer tomography, near infrared spectroscopy and a few other important techniques for determination of different quality attributes with emphasis on fruits and vegetables, and discusses their pros and cons for practical exploitation.
Conference Paper
Surface gloss, stiffness and density were considered to be the prime contributors to the freshness of eggplant fruit. The freshness index was defined as the ratio of product of relative spectral reflectance (surface gloss) and stiffness ratios to the density ratio. Surface gloss was measured in terms of relative spectral reflectance using a computerized spectral radiometer system while stiffness was determined as an initial slope of force deformation curve obtained on a uniaxial compression testing machine. Weight and volume for computing density of eggplant were determined by standard methods. These parameters were changed to consumers’ acceptable limit by storing the eggplants for different periods at 25±2°C temperature and 90±5 % relative humidity. Experiments were replicated 5-8 times and the average values were used to compute dimensionless ratios (values at any time divided by initial value) that were later used to determine the freshness index. Various forms of equations were tested for best fitting to the data. Freshness index of eggplant fruit decreased exponentially with storage period while it varied in form of power equation of weight and density ratios. It attained the lowest value (5.6 %) at acceptable limit of weight ratio of about 0.87. The best relationships between freshness index with weight and density ratios was found to be in form of power equation (correlation coefficient 0.99) while decrease in price of eggplant was seen linear (correlation 0.98) with computed freshness index by these equations. This showed that the developed freshness index might estimate the price of eggplants using these equations satisfactorily.
Article
Fresh mushrooms (Agaricus campestris) packed in polystyrene trays covered with polyvinylchloride (PVC) film were gamma irradiated with a dose of 3 kGy to delay senescence and extend shelf-life. Control and irradiated samples were stored at 10 ± 2°C and 94 ± 6% relative humidity (RH) for 17d. Some physicochemical analyses: weight loss; acidity; and texture (using a Universal Testing Machine) were performed to verify possible changes due to the irradiation treatment. Weight loss increased with storage time, without significant differences between control and irradiated samples. On day 14, irradiated mushrooms showed values which were considered still as acceptable (140 g/kg). A slight initial increase in acidity was observed in irradiated samples, which diminished with storage time. The force required to compress the mushroom cap between its edges decreased more steadily in control than in irradiated samples with storage time, probably due to the cap opening inhibition observed in irradiated mushrooms. Relaxation parameter and springiness showed no differences either between samples or along storage time. Shear force increased in every sample with storage, without significant differences between control and irradiated mushrooms.
Article
A glossmeter, suitable for measuring the gloss on curved surfaces has been constructed. The gloss of ripe banana, green bell pepper, orange, tomato, eggplant and onion were checked with an incident laser light at 45° and 60°. Reflected light was collected by photosensors and the image was analysed using appropriate software. L, a, b, °Bx, pH and gloss of fruits and vegetables were checked once they reached the stage of ready to eat. Eggplant and green bell pepper presented the highest gloss properties under investigating conditions, while banana and unwaxed orange exhibited the lowest sheen. Results of our glossmeter were compared with a commercial glossmeter, designed to check gloss of flat surfaces. In such operations it was necessary to peel and flatten the skin. Gloss of the fruits and vegetables were ranked in a similar way by both apparatus. Linear correlation was found between results of gloss measured at 60° by both apparatuses. It must be emphasized that intact fruits cannot be checked by the commercial glossmeter because of their curved surfaces.
Article
The X-ray computed tomographic (CT) scanner was used to monitor the internal quality changes in peaches during ripening. The physicochemical constituents were monitored and the X-ray absorption expressed in CT number was used as an index. Relationships between the CT number and the physicochemical contents were determined. Results showed that CT number, moisture content and titratable acidity decreased significantly with postharvest ripening time, while pH and soluble solids increased with postharvest ripening time. The X-ray CT number is directly related with density, moisture content and titratable acidity. The soluble solids and pH are inversely related with CT number. X-ray CT imaging can be used as an effective tool in the evaluation of peach internal quality.
Article
A non-destructive mechanical sensor (Cantifruit) was designed to measure the firmness of tomatoes. It consists of a small plunger constrained to penetrate slightly into the fruits, by using an accurate lever mechanism. A highly significant correlation exists between firmness measurements performed with this device and the Stable Micro System (SMS), fitted with the same plunger diameter. Using the Cantifruit, data related to firmness variability and changes are easily obtained. The firmness of a tomato varies about 12% around its circumference. In a single lot of tomatoes picked at the same time, the variability may exceed 25%. If the tomatoes are stored at 4–5 °C and 92–99% relative humidity (RH), their firmness decreases by about 20% over ten days.
Article
The quality of eggplant fruit (Solanum melongena L.) during prolonged storage may be impaired by the susceptibility of the fruits to deterioration and chilling injury at low temperature (< 10 °C). This work shows that eggplants harvested during winter (December–January) were more susceptible to chilling injury than those harvested during spring (March–April). Storing disinfected eggplant fruits inside an unperforated polyethylene (PE) bag enabled them to be stored at 8 °C for more than three weeks without sustaining any chilling injury, whereas disinfected but unbagged control fruits showed severe chilling injury. The cooling rate of the bag-packed fruit was significantly slower than that of the control fruit, and the temperature of the fruit packed in bags was always maintained at 0.5–1.0 °C above the storage temperature.
Article
A unique glossmeter, suitable for measuring gloss of curved surfaces, was used in parallel with a conventional, flat surface glossmeter to measure peel gloss of ripening Dwarf Cavendish bananas. Ripening of the bananas was accompanied by a gradual decrease in gloss, which correlated well with other chemical and physical changes in the banana, including pH, °Brix and starch content of the pulp and peel roughness. Most importantly, the decrease in gloss correlated well with changes in peel colour, the current indicator used to assess banana ripeness, which appropriately, correlated well with chemical and physical changes. It is believed that the decrease in gloss during ripening may be a result of a decrease in epicuticular wax content that was observed. Results suggest that peel gloss measurements have potential as a criteria for determining banana ripeness.
Article
Makhana is the popped expanded kernel of the gorgon nut (Euryale ferox) and is used as a delicious food in India. Presently, it is sorted, graded and used as an ingredient of various ready-to-eat products. High volumetric expansion of makhana increases transport cost and makes it too expensive in distant places. Makhana thus requires further processing to get some value-added products of minimum volume. To develop any kind of product and mechanized system for their production, physical properties are required. Furthermore, since makhana is a seasonal and regional crop its storage conditions are also needed for keeping it appropriately at processing centres. Physical properties of makhana at moisture contents ranging from 5 to 20% (dry basis) and equilibrium moisture content at relative humidities ranging from 11·2 to 88% at temperature 30°C were determined using standard techniques. Physical properties were found to be: test weight (weight of 1000 makhana) 286 to 384 g; bulk density 56·5–84·6 kg/m3; particle density 105–240·6 kg/m3; porosity 29·4–48·9%; angle of repose 33–35·6°; and static coefficient of friction 0·596–0·82 and 0·493–0·684 on galvanized iron and stainless steel, respectively. The equilibrium moisture content of makhana was found to be between 11·5 and 58·9% (dry basis) within the ranges of variables studied.
Article
Nuclear magnetic resonance (NMR) experiments were conducted to find desirable methods for maturity evaluation of avocado fruits. NMR image intensity, the ratio of the oil and water resonance peaks of the one-dimensional NMR spectrum, and both the spin-lattice relaxation time (T1) and spin-spin relaxation time (T2) of water in the fruit were found to correlate with maturity of the fruit. The technique of using a surface-coil NMR probe to obtain the oil/water resonance peak ratio of the signal from a region of an intact fruit produced the best result and has desirable features for high-speed sorting.
Article
Storage temperature is never constant in the distribution chain of fresh foods. Due to the temperature dependence of respiration of fresh produce and O2permeability of a packaging film, fluctuating temperatures result in changes of the internal O2and CO2concentration of Equilibrium Modified Atmosphere (EMA) packaged fresh produce.Therefore, the design of EMA packages was improved by adding mathematical models describing the effect of temperature, O2and CO2levels on produce respiration. The influence of temperature on respiration was described by an Arrhenius type of equation while the influence of O2and CO2on respiration was modelled by a Michaelis–Menten kinetic for 10 types of fresh-cut produce. Compared to unprocessed vegetables a higher temperature dependence of cut/shredded produce was observed. An integrated mathematical model characterized the effect of produce type, produce weight, temperature, O2and CO2dependence of produce respiration, film type, package area and temperature dependence of film permeability for O2in order to predict the internal O2concentration of an EMA package which was designed for equilibrium concentration of 3 mL/100 mL O2at 7°C. The model was validated by packaging 10 types of fresh-cut vegetables and comparing equilibrium O2levels with those predicted at six different temperatures between 2 and 15°C.
Article
Low temperature has been used to extend the shelf life of temperate fruits and vegetables since antiquity, while the negative effect of low temperature (<10oC) on the shelf life of tropical plants and commodities has been known since at least the eighteenth century. Low temperature storage has the additional benefit of protecting non-appearance quality attributes: texture, nutrition, aroma and flavor. Time of day when harvest is performed can influence shelf life. In addition, delays in cooling after harvest can reduce commodity shelf life and quality. In commercial handling, shelf life of commodities may vary greatly from laboratory studies. The distribution chain rarely has the facilities to store each commodity under ideal conditions and requires handlers to make comprises as to the choice of temperature and relative humidity (RH). These choices can lead to physiological stress and loss of shelf life and quality. This limitation, especially late in the handling chain during retailing, requires all participants in the distribution chain to increase their understanding of the need to improve management of handling, temperature and RH, to limit losses in quality. Simulated storage studies should be conducted under conditions that approximate the average to better levels of commercial practices.
Peel gloss as a potential indicator of banana ripeness. Lebensmittel-Wissenschaft und-Technologie
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Extending the shelf life of melongene (Solanum melongena L.) using polymeric films
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Maintenance of eggplant fruits quality inside lining during storage Gloss evaluation of materials
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Rosenberger I; Apelbaum A (1993). Maintenance of eggplant fruits quality inside lining during storage. Hssadeh, 73, 1120–1123, (in Hebrew with an English summary) Hunter R S (1952). Gloss evaluation of materials. ASTM Bulletin, 186, 48–55
Gloss evaluation of materials
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Non-destructive techniques for quality evaluation of intact fruits and vegetables—a review
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Designing equilibrium modified atmosphere packages for fresh-cut vegetables subjected to changes in temperature
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Maintenance of eggplant fruits quality inside lining during storage
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