The aim of this study was to examine the contribution of sugar, organic acid, neutral phenol, and anthocyanin fractions and added ascorbic acid to grape and pomegranate-nectarine juice total phenol, ORAC, FRAP, and DPPH values. Neutral phenol and anthocyanin fractions contributed ≥75% of the total antioxidant capacity (TAC) for both juices. Intrinsic synergy and antagonism among the fractionated constituents occurred inconsistently in each assay. Sugars and organic acids antagonized pomegranate juice neutral phenols and anthocyanins in the DPPH assay by 50% and the grape juice ORAC value by 21%, but were synergistic to the grape juice FRAP value. The added ascorbic acid was dose-dependently synergistic with pomegranate and grape juice total phenol, DPPH, and FRAP assays, but less so in the ORAC assay. Thus, the interactions between grape and pomegranate juice constituents determine TAC and total phenol values, and synergy in these assays could not be attributed solely to polyphenols.
The study was performed to evaluate the flavour profiles of low-fat comminuted sausage (LFS) as affected by the addition of various concentrations of glucose, fructose and sucrose combined with 0.1 m lysine. Among thirty-five volatile compounds, the concentrations of furfural, 2-furan methanol, 2-methoxy phenol, 2-methoxy-4-methyl phenol, myristicine and pentadecanal occupied approximately 60% of the total concentration of volatile compounds identified in full- and low-fat smoked sausages. Phenols and hetero-compounds derived mainly from the smoking process were the predominant chemical groups. Nine volatile compounds were affected by fat content and the reduction of fat predominantly increased the headspace concentration of myristicin and pentadecanal. The headspace concentration of total volatile compounds detected in LFS control was significantly higher than those of LFS treatments with the various sugars and lysine. The headspace concentration of most volatile compounds decreased with the addition of various sugars. The results indicate that the addition of glucose, fructose and sucrose at the concentrations higher than 0.05 m in combination with 0.1 m lysine delays the release of some flavour compounds in LFS.
Penicillium sp NIOM-02 was isolated from the marine sediment, produced red pigment. The pigment extracted from this fungus scavenged 2, 2-diphenyl-1-pycrylhydrazyl (DPPH) radical. Penicillium sp NIOM-02 grown in media containing corn steep liquor scavenged 72–88% of DPPH radical. During solid-state fermentation on wheat (S1), the fungus produced more pigment (9.232 OD Units). Penicillium sp NIOM-02 grown on sugarcane bagasse scavenged 91% of DPPH radicals. It secreted more amylase (246 U mg−1) in culture medium No. 5 and the zymogram analysis revealed its molecular mass (53 kDa). The taka-amylase like character of amylase was determined by acarbose incorporated studies in the culture media. Production of pigment and radical scavenging activity of Penicillium sp NIOM-02, suggested its applications in food, pharmaceuticals and nutraceutical industries.
Response Surface Methodology (RSM) was used to establish the optimum time and temperature for production of acid-hydrolysed winged bean protein (aHWBP) and acid-hydrolysed soybean protein (aHSBP). Seven hours of hydrolysis at 125 °C was the optimum condition for producing aHWBP, whereas it was 5 h of hydrolysis at 125 °C for production of aHSBP. Although aHWBP and aHSBP produced using these conditions had favourable sensory qualities, they were found to have up to 25 mg kg−1 of 3-monochloropropane-1,2-diol (3-MCPD). This exceeds the maximum level permissible in Commission Regulation (EC) No 466/2001. However, additional alkaline thermal treatment at pH 8.5 for 2 h at 100 °C effectively reduced the 3-MCPD contents of aHWBP and aHSBP to undetectable levels. aHWBP has a distinctive flavour, which is different from that of aHSBP. The former has higher mean scores for meaty and vegetable attributes but lower mean scores for soy, umami and beany attributes than the latter.
The effect of commerical olive oil refining processes on the total polyphenol and 1,2-diphenol content of the oil was investigated. the mean losses of total polyphenols and 1,2-diphenols of the crude oils were 84-87% and 79-88% respectively. There was no difference between the chemical and physical refining processes in reducing phenols in the oil samples.
Commercial wheat germ lipase inactivation was analysed at various temperatures with reference to conventional and microwave heating. A temperature controlled water-bath was used for conventional heating. A custom designed microwave temperature control system was used to maintain test samples at selected temperatures either by full exposure to microwaves (microwave heating) or partial exposure by immersion in water (in a beaker) maintained at the desired temperature using the microwave oven (mixed mode). Lipase inactivation was analysed using first-order kinetics resulting in activation energies (Ea) of 20.9, 25.4 and 18.7 kcal mole-1 for the conventional, microwave and mixed mode heating, respectively. the activation energies of conventional and mixed mode heating were somewhat more comparable, while the microwave mode resulted in a slightly higher activation energy. the higher enzyme inactivation rate constants observed under microwave heating conditions were attributed to possible non-thermal effects associated with microwave energy
The non-edible portion of cauliflower (cauliflower waste) was subjected to drying by different methods. While conventional sun drying (CSD) took 1920 min to dry the waste, microwave drying (MWD) took only a few minutes. As against the L value of 41.27 in samples with fresh cauliflower waste, the sample dried at 50 °C showed L value of 38.16, and those dried at 200 °C indicated an L value of 16.61. Highest glucoamylase (GA) activity was found in the samples containing waste dried at 50 °C and the least in samples dried at 200 °C. However, in samples containing waste dried at 70 °C, using combinations, such as MWD and CSD, MWD and drying at 50 °C, CSD showed comparable GA activity. The results indicate that the sample dried using the combination of MWD and drying at 50 °C resulted in shorter drying period, good colour retention in the final product, and its incorporation resulted in significant enzyme production.
The heat resistance of Staphylococcus aureus NCTC 10652 in tris-maleate buffer pH 7.0 was increased by 4 or 8% w/v NaCl (P= 0.001). At pH 6.5 the D60°C in both buffer and meat macerate was increased by 8% w/v NaCl. Addition of NaNO2 had little effect on the heat resistance.
Ethyl acetate was found to be produced in large quantities in aged cultures of the soy yeast Saccharomyces rouxii NRRL Y-1096 grown on medium containing glucose. The synthesis of ethyl acetate was investigated. The present study shows that the process of ester synthesis is essentially an aerobic one. Glucose and ethanol were the main substrates for the synthesis of ethyl acetate although to a limited extent the yeast cells were also able to synthesize the ester from ethanol alone but not from either glucose or acetate. From the results of the present study, it is suggested that the flavour-producing moromi stage of soy-sauce fermentation is necessarily a prolonged one because ethanol has first to be produced in a semi-anaerobic environment for the synthesis of the esters responsible for the characteristic bouquet and flavour of the mature soy-sauce. It should therefore be possible to shorten this stage of soy-sauce fermentation by the addition of ethanol to the moromi.
The glucose metabolism of Saccharomyces rouxii NRRLY—1096, the soy yeast, under aerobic and anaerobic conditions, was investigated. The study was carried out at pH 4.5 and 7.0 with cells previously grown at either pH. The pH at which the cells had been grown as well as the pH at which glucose was fermented were found to affect the pattern of fermentation. A typical yeast type fermentation was obtained with cells grown at pH 4.5 and fermenting glucose at the same acid pH. An ability to fix CO2 for formic acid synthesis was demonstrated by cells grown at neutral pH. Acetic acid was produced by cells fermenting glucose at neutral pH irrespective of the pH at which they had been grown. Various schemes of glucose fermentation were therefore proposed. From results of the present study, optimal conditions for the formation of the desired fermentation products, resulting in the flavour and bouquet of good quality soy sauce, are suggested.
The effects of sodium chloride concentration, pH and temperature on the growth characteristics of Saccharomyces rouxii NRRLY-1096 are described. It was found that sodium chloride increased the lag phase of the growth curve and reduced the total amount of growth. Doubling time was less at 37°C during the exponential growth phase as compared to that at room temperature (28°C). Total amount of growth was however, greater at room temperature. Saccharomyces rouxii NRRLY-1096 grew over a wide pH range in the presence of relatively high concentrations of salt, but pH 4.0 to 6.0 was most favourable to its growth.
SummarySDS gel capillary electrophoresis (Beckman–Coulter ProteomeLab) and the lab-on-a-chip technology (Agilent 2100 Bioanalyzer) were used to quantify the relative amount of 7S and 11S fractions in twenty different soybean cultivars. The better repeatability of the migration times and peak areas was achieved for the Bioanalyzer. Both lab-on-a-chip instrument and a traditional capillary gel electrophoresis were shown to be adequate for analysis of soy-based products. Integrating the area of peaks within a certain range of molecular weights was used to calculate the relative content of each protein subunit. Poor agreement in the classification in the protein subunit groups between the two instruments was observed. Therefore, the approach of visual identification taking into account both the variability in the position of the peaks and the detection of different number of peaks between the profiles was applied. This resulted in statistically significant correlation being observed between 11S/7S ratios determined by Bioanalyzer and ProteomeLab (R = 0.82). The reported differences in 11S and 7S content between the studies are likely to be affected by the differences in the techniques used to analyse soy protein subunits. A brief presentation of the chemometric analysis of electrophoretic profiles as a common method for transforming electrophoretograms to multivariate data sets is shown.
The heat resistance of spores of Clostridium botulinum strain 213B heated in phosphate buffer (pH 7.0) was determined over the temperature range 120 to 140°C using a computer controlled thermoresistometer. The predicted D121°C value of approximately 0.13 min and z value of 11.0°C (obtained by linear regression) was close to the classical D121°C of 0.2 min and z value of 10°C used in process calculations. These data indicated that, according to the heat resistance of this culture, the z value of C. botulinum can be considered constant over the whole range 120 to 140°C. This also provided support for the recommended classical process calculations, using a z value of 10.0°C, being adequate if extrapolated to 140°C.
The effect of the addition of a β-glucan fibre fraction from barley to durum wheat pasta was evaluated in terms of cooking characteristics, structure, texture and in vitro starch digestibility. Barley β-glucan (BBG) fibre fraction was incorporated into pasta at 2.5%, 5%, 7.5% and 10% inclusion rates. Incorporation of the BBG fibre fraction to pasta attenuated reducing sugar release during in vitro digestion, the magnitude of reduction being related to the level of BBG fibre fraction inclusion. Changes to pasta cooking quality and texture were observed with BBG fibre fraction addition, including greater solid loss during cooking, increased pasta swelling and loss of hardness compared with the control pasta. Investigation of pasta microstructure and characterisation of starch gelatinisation events indicated that a combination of changes to the starch–protein matrix and the high water binding capacity of β-glucan alters the physico-chemical properties and digestibility of the pastas.
As aquaculture has developed, a range of bacterial diseases have been encountered that have caused both major production problems and animal welfare difficulties. These diseases were initially controlled almost exclusively by the use of antimicrobial agents. Fish farming is now a sufficiently large and mature an industry to have justified the development of an effective range of vaccines that have largely supplanted the use of antimicrobial agents for most bacterial diseases in salmonid farming in Europe and North America. For most salmonid bacterial diseases, use of antimicrobial agents is now largely confined to emergency use in the event of breakdown of vaccine protection. In addition to the increasing availability of vaccines, aquaculture is steadily developing a range of improved husbandry methods to reduce the impact of disease. Although there is evidence that antibiotic resistance can be selected for in normal therapeutic use in aquaculture, the risks of transfer of such resistance to human consumers by any of the possible routes appears to be low. Where new species are under development for aquaculture and during the development of these species, bacterial diseases may be expected to occur that will need use of antimicrobials for disease control before vaccines can be developed. If antimicrobials were not available for use with new species, development would be likely to transfer to countries with poorer controls on antibiotic use. Use of antimicrobial agents in ornamental fish, particularly in some exporting countries, is significant, and evidence exists that multiple antibiotic resistant bacteria may be frequent in such animals. Although ornamental fish are not eaten, they do enter homes and are in close contact with humans.
This work describes the application of high resolution 13C nuclear magnetic response (NMR) to the study of fatty acid composition in animal fats. It allows both the proportions of saturated, mono- and polyunsaturated fatty acid chains and the positional isomerism on glycerol to be determined. Olefinic carbon shifts gave quantitative information on the distribution of saturated, mono- and polyunsaturated fatty acid chains in animal fat triglycerides. Carbonyl carbon shifts gave information about the degree of saturation of fatty acid chains and their positions on the glycerol. The NMR values agree with the results from gas chromatographic analysis.
Protein extractability, muscle pH and organoleptic toughness have been measured in cod fillets stored for up to 34 weeks at −7°C and −14°C. The decrease in protein extractability and the increase in toughness of fillets stored at −7°C proceeded at a faster rate than in fillets stored at −14°C. In order to assess if a fillet stored at −7°C or −14°C had an acceptable or a tough texture it was necessary to measure both protein extractability and muscle pH.
Dairy products are suitable vehicles for delivering beneficial microorganisms to consumers. Both Lactobacillus reuteri RC-14 and Lactobacillus rhamnosus GR-1 are considered as probiotic agents with therapeutic properties. The objective of this study was to monitor growth and survival of these bacteria in milk during storage period. Four formulations of milk (1% fat) with 0.33% yeast extract (Y), 0.4% inulin (I), 0.33% yeast extract and 0.4% inulin (YI) and one with no additives (N) were prepared. The mixtures were autoclaved for 15 min, cooled to 37 °C and inoculated with 1% of starter culture. They were then incubated anaerobically at 37 °C overnight. Viable numbers of L. reuteri RC-14 and L. rhamnosus GR-1 were determined after 1, 7, 14, 21 and 28 days of storage at 4 °C. Both bacteria were able to grow and survive in all samples; however, they showed a higher survival rate (P < 0.05) in YI treatment. After 1 day of storage, the total colony counts of treatment YI for L. reuteri RC-14 and L. rhamnosus GR-1 were 2 × 108 and 1 × 109 CFU mL−1, respectively. The total colony counts for treatment YI decreased by 1 log cycle for both bacteria after 28 days of storage. The results of this study indicate that these bacteria can remain viable over the storage period, and there is potential for incorporating them into fermented dairy products.
The fat content and fatty acid profiles of 14 varieties of date seeds were measured by gas chromatography–mass spectrometry (GC–MS). Fat content ranged from just over 5% (w/w) to about 9%. Eleven fatty acids were found with nearly 50% oleic acid in most varieties and an overall range from about 12 to 0.2%.
The differences between samples were ascribed to both varietal and cultural differences. Some varieties had similar names but it is not known whether they are identical.
The uses of dates seeds, which are currently only used for animal feed, is assessed with suggestions for potential uses as sources of edible oils and pharmaceuticals.
SummaryA computer-controlled thermoresistometer for the determination of the heat resistance of bacterial spores has been designed and constructed. The thermoresistometer is capable of operating between 100 and 150°C0.1°C with exposusre times as short as 0.1 sec. Five samples (0.01 ml) of spore suspension can be exposed to steam at each time/temperature combination using a computer-controlled piston-driven exposure system. Temperature control of the apparatus is achieved using platinum resistance probes linked to the computer, which then actuates a variable steam control valve.
The effects of doses of gamma radiation of up to 16 Mrad on some plastic packaging materials have been studied in relation to properties considered desirable for the vacuum packing of fish. Nylon 11 appears to be the most suitable in terms of the tests applied.
In this study we investigate the spoilage of ultra high temperature UHT mango juice as well as a carbonated fruit juice blend to identify organisms contributing to the spoilage. The mango concentrate, the final product, as well as the other ingredients used during manufacturing, were tested for the presence of Alicyclobacillus by polymerase chain reaction (PCR) and sequencing analyses. Microbiological examination of the mango pureé and spoiled fruit juices, using YSG agar [yeast extract 2 g, glucose 1 g, soluble starch 2 g, pH 3.7 (adjust with 2N H2SO4), H2O 1000 mL, bacto agar 15 g] incubated at 55 °C, detected sporeforming, acid dependent and thermotolerant bacteria. The hyper variable region of the 16S rDNA was amplified. The nucleotide sequence of the PCR fragments was determined using the ABI Prism 310 automated DNA sequencer and the collected sequencing data were analysed and compared with the non-redundant database using NCBI-BLAST. Alicyclobacillus acidocaldarius were isolated and identified by 16S rDNA gene sequences analyses. The results indicated that the mango purèe, as well as the final product of mango juice and the fruit juice blend, were positive for Alicyclobacillus. The preventative measures of low pH, pasteurization of mango juice and the subsequent use of aseptic packaging were not regarded as sufficient to prevent the outgrowth of Alicyclobacillus spoilage organisms.
A molecular f(DNA) method based on 16S rDNA polymerase chain reaction (PCR) was developed by employing universal oligonucleotide primers followed by direct automated sequencing of the PCR amplicon. The employment of the methodologies allowed for the reliable identification of collection of eubacteria isolated from several food and water sources. Highly variable portions of the 16S rRNA sequence provided unique signatures to any bacterium and useful information about relationships between them. Employment of partial 16S rDNA PCR and sequencing provided a valuable and reliable method of identification of environmental bacteria associated with food and water.
In the hot breast and leg muscles of broiler chicken the level of ATP, the ‘R’ value, the lactic acid content, the pH value, the length of sarcomers, the water and fat retention capacity, the fat emulsion stability, thermal drip, and the extractability of protein fraction were investigated. It was found that in the breast muscles the onset of rigor mortis commenced within 30–60 min, and in the leg muscles as early as 15–30 min after killing of the birds. The deepest rigor mortis occurred between the first and fourth hour, and then gradually declined, sooner in the leg than in the breast muscles. The addition of sodium chloride (2.0–2.5%) to the minced pre-rigor meat not later than 40 min after slaughter, or better, an injection of NaCl brine into intact muscles 15 min after slaughter of birds, preserved their good technological properties.
The tenderness and the thermal drip of hot salted and chilled salted muscles showed no significant differences, but water retention and fat emulsifying capacity were better in the hot salted meat samples. The hot salted and cooked muscles were preferred by the sensory panel to corresponding samples of chilled muscles.
From the hot salted chicken meat more sarcoplasmic and myofibrillar proteins were extracted than from meat salted after chilling. However, after frozen storage the extractability of myofibrillar proteins were higher in the salted chilled meat.