A comparison of the effects of storage of raw milk at 2°C and 6°C on the yield and quality of Cheddar cheese

The advantages of storing raw milk, which is to be used for Cheddar cheese manufacture, at 2°C rather than at 6°C was examined. Storage of milk at the lower temperature effectively reduced the level of psychrotroph growth, and after 4 days the psychrotroph counts in samples stored at 2°C were 100-fold lower than those found in samples stored at 6°C. There was no advantage in terms of cheese yield in storing milks at the lower temperature, but an overall improvement in cheese quality was noted in samples produced from milk stored at 2°C.     

Effect of Eryngium caeruleum essential oil on microbial and sensory quality of minced fish and fate of Listeria monocytogenes during the storage at 4°C

The present study investigated in vitro antimicrobial activity of Eryngium caeruleum essential oil (EEO) against five foodborne pathogenic bacteria based on microdilution and disk diffusion methods. Moreover, its effects on specific spoilage microorganisms, inoculated Listeria monocytogenes, and its sensory changes in minced fish were evaluated during 12 days of storage at refrigeration temperature. The results showed that Staphylococcus aureus and Escherichia coli were the most sensitive and the most resistant bacteria with a minimum inhibitory concentration of 0.125 and 1 mg/ml, as well as inhibition zones of 15.66 and 11.66 mm, respectively. Regarding the antimicrobial effect of EEO on the microbial profile and inoculated L. monocytogenes, treating with 0.4% EEO caused a significant decrease in the studied microorganisms when compared to the control group (p < 0.05). In addition, considering the sensory evaluation, the best scores were observed for the samples treated with 0.2% and 0.4% EEO. However, none of the groups obtained acceptable scores until the final day of storage except for the color attribute. In general, sensory evaluation and its correlation with microbial counting indicated that the treatment with 0.4% EEO was able to preserve the microbial quality of the minced fish at refrigeration temperature without any undesirable sensory effects.     

Effect of different binders on the quality of enrobed buffalo meat cutlets and their shelf life at refrigeration storage (4±1°C)

To enhance the binding and quality of enrobed buffalo meat cutlets (EBMC), a meat emulsion at 0%, 15%, 20% and 25% replaced the cooked meat in the formulation. Emulsion containing products had significantly higher moisture contents and texture scores compared to the control. Emulsion at 20% level could be incorporated in enrobed buffalo meat cutlets to enhance their quality. Addition of 1% egg white powder improved the quality of EBMC compared to control, while a 3% level had adverse effect on the sensory attributes despite giving higher product yield and lower shrinkage. Cutlets with refined wheat flour had significantly higher protein and fat contents. It had also higher acceptability followed by corn flour, potato starch and tapioca flour. TBARS of enrobed samples remained lower than controls throughout the storage period. Mesophilic count remained below log3cfu/g for both samples during storage. Uncoated products and enrobed products were acceptable up to 10th and 15th day, respectively. Enrobing of buffalo meat cutlets improved their acceptability and shelf life under refrigeration storage.     

Effect of low-dosage electron beam irradiation on antioxidant activities of navel oranges during storage at a low temperature of 3°C

Food Science and Biotechnology - Effects of low-dosage electron beam irradiation on antioxidant activities of Navel oranges during storage at a low temperature of 3°C were studied. Oranges...     

Effects of lyophilized red cabbage water extract and pH levels on the quality properties of pastırma cemen paste during chilled storage

Pastırma is a dry-cured and dried meat product and its coating with a paste defined as “cemening” is one of the most important stages in the formation of its color and quality. However, discoloration is an important problem during production and storage. In this study, the effects of lyophilized red cabbage water extracts (LRCWE; 0.0%, 0.4%, 0.8% and 1.2%) and pH values (4.0, 4.5, 5.0, 5.5 and 6.0) on the color quality and storage stability of the pastırma cemen paste during chilled storage (4 ± 0.5 °C for 90 days) were investigated. LRCWE contain high amounts of phenolic compounds and anthocyanins. Addition of LRCWE and low pH values improved color properties of the pastırma cemen paste (P < 0.01). The best results for the a1 value were determined in cemen paste with 1.2% LRCWE. The most effect of the LRCWE was determined in low pH values cemen paste (4.0 and 4.5), thus, pH levels below 5.0 were determined as the threshold value for the effectiveness of extract in pastırma cemen paste. In addition, color stability was maintained better in low pH values cemen paste during storage. By lowering the pH values of the pastırma cemen paste, the color quality was preserved and discoloration during storage was prevented.     

Effect of a 10-day ageing at 30°C on the texture of dry-cured hams processed at temperatures up to 18°C in relation to raw meat pH and salting time

The aim of this study was to investigate the effect of a 10-day ageing at 30 ± 2 °C on the texture of dry-cured hams processed at temperatures up to 18 ± 2 °C for 12 months in relation with raw ham pH and salting time. Three pH groups (semimembranosus muscle at 24 h post-mortem: Low pH < 5.7, Medium pH = 5.7  pH  5.9, and High pH > 5.9), three salting times (6 d, 10 d and 14 d) and two ageing temperatures (18 °C and 30 °C) were investigated. Physicochemical characteristics, instrumental and sensory texture and product sliceability were evaluated on biceps femoris and semimembranosus muscles. Hams with pH_SM24 < 5.7 should be avoided in order to reduce the incidence of texture problems in dry-cured ham elaboration. Texture problems are especially important in hams with a reduced salt content that are mechanically sliced (not frozen). A 10-day ageing at 30 °C could be useful for reducing the soft texture problems in dry-cured hams processed at temperatures up to 18 °C for 12 months without affecting the product flavour.     

Quality changes of ready-to-eat ginseng chicken porridge during storage at 25°C

Ready-to-eat (RTE) ginseng chicken porridge was heated in a retort with an F-value of 4.0 after being packaged in a gas-tight plastic tray (PP/EVOH/PP) with top film (PET/PA/CPP). Various quality changes were investigated during the storage for 28weeks at 25°C. Over the storage period, microorganisms were not detected above 1.0 log cfu/cm(2) (detection limit). The viscosity increased sharply from 775 to 2025cp for initial 4weeks and increased steadily until 16weeks, with a slight reduction thereafter. During the 28weeks of storage, the ratio of residual oxygen and pH decreased from 10.8% and 6.49 to 5.7% and 6.05, while retrogradation degree increased from 0% to 55.9%. Hunter L(?), b(?), and ΔE values increased until 20weeks and remained for the rest of storage. Based on sensory, microbiological and physicochemical evaluations, the RTE ginseng chicken porridge could be marketable for at least 24weeks at 25°C.     

Quality changes and shelf life of imported vacuum-packaged beef chuck during storage at 0°C

The objective of this study was to investigate differences in adipose tissue fatty acid composition among stress genotypes as well as to determine relationships of those fatty acids with performance, carcass and meat quality traits. Haplotypic analysis of parents and offspring was employed to assign 48 pigs to three stress genotypes of swine. Individual fatty acid profiles were determined on subcutaneous backfat. Stress genotype had a significant effect on the proportions of C14:0 (P<0.05), C16:0 (P<0.10), C16:1 (P<0.05) and C18:0 (P<0.05) fatty acids. After adjusting for stress and gender, there was a negative correlation between backfat thickness and essential fatty acids (linoleic and linolenic) (P<0.001). In contrast, the correlation of loin muscle area with C18:2 (P<0.01) and C18:3 (P<0.001) was positive. The degree of fat firmness was negatively correlated to the proportion of total unsaturated fatty acids (P<0.01). No significant correlations were observed between fatty acid contents and lean meat quality traits.     

Determination of biogenic amines in fresh unpacked and vacuum-packed beef during storage at 4°C

Biogenic amines, putrescine, cadaverine, and histamine were determined in unpacked and vacuum-packed beef; during storage at 4°C for 12 and 35 days, respectively, under the same conditions. Analysis by High Performance Liquid Chromatography in both kind of samples, showed variation of cadaverine and histamine with an increasing tendency to a definite increase of putrescine. In unpacked samples, maximum mean contents for each amine reached 10.4, 5.2 μg/g for putrescine and cadaverine, respectively (12th day) and 2.2 μg/g for histamine (5th day). The total amine content reached 16.5 μg/g (12th day). After 8 days of storage, organoleptic fall-off began and, on the 12th day, all samples were disqualified. In vacuum packs, amine levels increased after 19 days. Maximum levels were determined for putrescine on the 35th day (36.3 μg/g), for cadaverine on the 26th day (28.9 μg/g) and for histamine on the 35th day (19.0 μg/g). Although the vacuum-packed beef was organoleptically acceptable up to 35 days, the total amine levels were greater than 5 μg/g after the 12th day, indicating a leveling off of quality.     

Effect of thermal and high-pressure processing on the nutritional value and quality attributes of a nectarine purée with industrial origin during the refrigerated storage

The application of hydrostatic high pressure on an industrial line of nectarine (Prunus persica L.) purées was assessed in comparison with the traditional thermal treatment of pasteurization. Changes after thermal processing (85 °C, 5 min) and after high-pressure processing (HPP: 450 or 600 MPa for 5 or 10 min) and during the refrigerated storage (60 d) of an industrially produced nectarine purée were evaluated. Conventional heat pasteurization as well as HPP showed similar microorganisms' inactivation and maintained the microbial stability of purées until the end of the refrigerated storage (60 d). In general, thermally treated purée and HP-treated purée at 600 MPa showed more intense color changes after processing than the other treatment. In addition, thermally treated purée showed more intense color changes during storage than HPP. The highest carotenoids extractability was found in those purées treated at the lowest high-pressure-treatment intensity and holding time (450 MPa/5 min), but at the end of the storage (day 60), no differences in individual or total carotenoid levels were found between the purées. HPP at 600 MPa/10 min showed the highest polyphenols content after the treatment and during the storage. At day 0, significantly higher values were found of total antioxidant activity in purée HP-treated at 450 MPa/10 min than in untreated purée; while at the end of the storage, HP-treated purée at 600 MPa/10 min had the highest antioxidant activity. Hydrostatic high-pressure application in the industrial line of nectarine purée presented some advantages compared to the thermal treatment; however, some of the changes found were lessen during the storage period. In addition, more studies need to be carried out for HP-treatment intensity optimization.     

Quality of giant freshwater prawn (Macrobrachium rosenbergii) during the storage at −18°C as affected by different methods of freezing

This study investigated the effects of liquid nitrogen quick-freezing, ?35°C air-blast freezing, and ?18°C refrigerator direct-freezing on quality retention of frozen giant freshwater prawns using various indicators: microscopic structure, physicochemical, texture, and color properties. The results showed that the shelf lives of prawns treated with liquid nitrogen quick-freezing, ?35°C air-blast freezing, and ?18°C refrigerator direct-freezing were about 20, 12, and 8 weeks, respectively, in terms of total volatile basic nitrogen content and K-value. Meanwhile, liquid nitrogen quick-freezing could effectively improve texture property of frozen giant freshwater prawn. These findings confirm that liquid nitrogen quick-freezing is a promising method to extend the shelf life of frozen prawns.     

Effect of packaging atmosphere and pH on the virulence and growth ofYersinia enterocoliticaon pork stored at 4°C

Growth and virulence of pathogenicYersinia enterocoliticawere investigated on high (pH>6.0) and normal (pH<5.8) pH pork packaged in modified atmospheres and stored at 4°C. Modified atmospheres used in the study were vacuum packaging and saturated CO₂. Pork was packaged in a high gas barrier packaging film and examined over a 30-day period. Phenotypic characteristics were used to detect the presence of the virulence plasmid ofY. enterocoliticaafter exposure to the pork packaging and storage regimen. Phenotypic characteristics ofY. enterocoliticaisolates from pork loin stored at 4°C for 30 days that were studied included Congo red uptake, calcium dependence and autoagglutination in methyl red Voges–Proskauer broth and tissue culture medium. Numbers ofY. enterocoliticaon the lean surface of high pH pork slices increased approximately 2.7logcfucm⁻²when vacuum packaged and stored at 4°C for 30 days. Storage of inoculated normal pH pork in 100% CO₂resulted inY. enterocoliticaremaining in the lag phase over the storage period. Virulence ofY. enterocoliticawas maintained in 25 to 35% of isolates following storage for 30 days at 4°C in vacuum- and CO₂-packaged meats and was not affected by pH of the pork loin.     

Effects of α-tocopherol level in raw venison on lipid oxidation and volatiles during storage

Relationships between α-tocopherol concentration in the muscle and development of lipid oxidation or volatiles in raw venison were studied. Fourteen Japanese Shika Deer (Cervus nippon) were fed various amounts (0–3.0 g of α-tocopheryl acetate per animal) during the different periods (0–37 days) and then M. longissimus thoracium et lumborum (LD muscles) with a range of α-tocopherol concentrations (4.1–15.1 mg/kg tissue) were obtained. For stabilizing the lipid during storage for 11 days under air, over ca. 9 mg of α-tocopherol per kg tissue were required based on levels of 2-thiobarbituric acid reacting substances (TBARS) numbers. Nine compounds were identified in headspace volatiles, and one of the volatiles was hexanal which has been recognized as off-flavour component. For depressing the hexanal evolution, at least ca. 9 mg of α-tocopherol per kg tissue were also required for 11 days’ storage. This value was much higher than other species. The reasons for higher requirement of α-tocopherol were possibly due to the higher concentration of unsaturated fatty acid and myoglobin in venison.     

Effect of α-tocopherol on the oxidative stability of horse oil-in-water emulsion during storage

Food Science and Biotechnology - Horse oil-in-water (O/W) emulsions were prepared and α-tocopherol was added at 0, 100, 200, and 500&nbsp;ppm (α-T0, α-T100, α-T200,...