THE SHELF-LIFE EXTENSION OF HADDOCK IN CARBON DIOXIDE-OXYGEN ATMOSPHERES WITH AND WITHOUT POTASSIUM SORBATE

Fresh haddock, whole fish or fillets, treated or not with various potassium sorbate dips, were sealed in gas impermeable bags containing gas atmospheres of 60% CO₂, 20% O₂ and 20% N₂, air or vacuum, stored on ice in insulated AIRBOX containers at 0°C and subsequently assessed using the Torry freshness scale after 11 to 18 days storage. The trends in the data suggested higher freshness scores for gas and gas plus dip compared with the air and vacuum packs. The dip alone was not effective. It was important to maintain the fish at 0° C.     

SHELF-LIFE EXTENSION OF RAW BROWN SHRIMP (PENAEUS AZTECUS) WITH POTASSIUM SORBATE IN ICES AND DIPS

The shelf-life of shrimp, as indexed by psychrotrophic bacterial counts, was extended approximately 1.0, 1.9, and 3.1 days using levels of 0.05%, 0.1%, and 0.2% potassium sorbate-containing ice, respectively. Shelf-life was extended an additional 0.5 to 2.5 days when a 3% potassium sorbate dip was administered prior to storage on modified ice. In all cases, potassium sorbate extended the lag phases of the spoilage bacteria.     

THERMAL CONDUCTIVITY OF CHICKEN MEAT AT TEMPERATURES BETWEEN −75 AND 20°C

Effects of temperature and time postmortem on the thermal conductivity of white and dark chicken meat were studied using a line heat source thermal conductivity probe to measure thermal conductivity. The effect of time postmortem was determined at body temperature and 20° C by leaving probes in whole birds for periods of 1–2 days; time postmortem had no significant effect. The effect of temperature was studied at temperatures of 20, 10, 0, −10, −20, −40 and −75°C using cylindrically shaped samples 3/4 in. in diam × 11/2 in. long. 48 samples were used from 24 7-lb cockerels. Three thermal conductivity measurements were made on each sample at each temperature level. The effect of temperature was similar to that reported in the literature for other meats. The following equations may be used to express the results obtained for white meat: k(Watt/m-°C) = 0.476 + 0.00060T(°C) (0–20°C) and k(Watt/m-°C) = 1.07 − 0149T − 1.04 × 10⁻⁴T²(−75 to −10°C). Similar expressions were obtained for dark meat.     

IMPROVEMENT IN MICROBIOLOGICAL QUALITY AND SHELF-LIFE OF BUFFALO MEAT AT AMBIENT TEMPERATURE BY GAMMA IRRADIATION

The effect of low dose gamma-irradiation (2.5 kGy) on the shelf-life of prepacked fresh buffalo meat at ambient temperature (28–30C) in terms of microbiological, chemical and sensory qualities was studied. Unirradiated samples initially showed the presence of Enterobacteriaceae and Staphylococcus spp. These gradually increased during storage. After 12 h of holding , Clostridium spp. were observed in these samples. On the basis of microbiological, chemical and sensory analyses, the shelf-life was limited to 18 h. In contrast , Clostridium spp. and Enterobacteriaceae were not detected in irradiated samples throughout the storage period and Staphylococcus spp. were detected only after 12 h of holding. Irradiated samples had a shelf-life of 42 h.     

EFFECTS OF PRETREATMENT WITH ROSEMARY (ROSMARINUS OFFICINALIS L.) IN THE PREVENTION OF LIPID OXIDATION IN SALTED TILAPIA FILLETS

ABSTRACT

To delay lipid oxidation during meat processing, synthetic antioxidants have been used in the food industry, but the consumers' concern over their toxicity increased interest in research with natural antioxidants. The aim of this work was to analyze the water activity (A_w), thiobarbituric acid reactive substances (TBARS), moisture and trichloroacetic acid‐soluble nitrogen (TCASN) in brined tilapia fillets treated or pretreated with natural rosemary extract (Rosmarinus officinalis) and stored for 240 days at ?18C. Higher A_w (0.900 ± 0.010) and moisture (70.13 ± 0.20) values were observed in the pretreated fillets. The TBARS values in the treatment (3.31 ± 0.79) and pretreatment (3.39 ± 0.53) were half the value of the control treatment (6.14 ± 1.21) at 240 days. Statistical differences were observed in TCASN values in 180 (0.112 ± 0.020) and 240 (0.132 ± 0.017) days, with the pretreatment showing a more protective effect in protein oxidation. In this study, rosemary proved to be protective during the frozen storage, especially when its extract was used as pretreatment, before the salting process.

PRACTICAL APPLICATIONS

Fish consumption is highly elastic, because the annual average consumption of seafood per person in Brazil is only 6.8 kg. The federal government has set a goal to increase it to 12 kg by 2007. Salting is an older food preservation process still used today, and is extremely important because, despite advances in food technology, increased monitoring and improved knowledge, it is emphasized as an easy, cheap and effective process that does not require refrigeration. Tilapia is a highly prolific fish, with a production volume that is increasingly higher each year in Brazil. Therefore, it calls for interesting research to allow an increased shelf life for this species.

     

CO/CO2/N2三种气体协同对冷却猪肉保鲜及护色效果的研究

为了延长冷却肉的货架期,采用添加一定浓度CO的方法进行护色处理,CO能与肌红蛋白(Mb)强烈结合形成碳氧肌红蛋白(MbCO).使肉在货架期内呈现樱桃红色.研究在混合气体中添加低浓度的CO气调包装对冷却猪肉的保鲜效果,测定贮存过程中的微生物、理化和感官指标(特别是色泽)的变化,确定适合的冷却猪肉气调包装混合气体比例为1%CO/50?2/49%N2,不但延长了货架期,而且使冷却肉在整个货架期内呈现诱人的亮红色.     

PHYSICAL AND CHEMICAL CHANGES IN VACUUM PACKAGED PARMIGIANO REGGIANO CHEESE DURING STORAGE AT 25, 2 AND −25C

Parmigiano Reggiano (PR) cheese, packed in single 20g portions under vacuum, was stored at three different temperatures (25C, 2C and ?25C) to evaluate chemical and physical changes in the product during 120 days of storage. There was no increase in lipid oxidation, even though the presence of pentane in the head space showed that the PR samples were already slightly oxidized following the 18 months of ripening process. Color and water activity determinations led to the hypothesis that the lipid fraction migrated to the sample surface when stored at 25C. Other changes observed by the authors influenced the modification of the flavor and a decrease in the overall acceptance of the PR samples packed under vacuum and stored at room temperature. However, they did not seem to be related to lipid oxidation.     

高效液相色谱法测定野蔷薇果中Vc含量的研究

建立一种高效液相色谱法测定野蔷薇中Vc含量的新方法.采用Diamonsil 5μ C18反相柱(200mm×4.6mm×5μm)分离;流动相为甲醇-0.01%磷酸水溶液(3:7,体积分数);柱温25℃;流速1.0mL/min;二级管陈列检测器,检测波长254nm.Vc在浓度为20mg/L～1500mg/L范围内呈良好的线性关系,线性回归方程为y=17.136x 120.8,相关系数为0.9992,方法回收率为97%～101%相对标准偏差小于3%.该方法简便、快速、准确、适合于测定其它水果和蔬菜中Vc的含量.     

BEHAVIOR OF STAPHYLOCOCCUS AUREUS IN REFRIGERATED AND FROZEN GROUND BEEF AND IN TURKISH STYLE SAUSAGE AND BROTH WITH AND WITHOUT ADDITIVES

Staphylococcus aureus 42E was inoculated into raw ground beef which was stored at 4C and -27C. Turkish style sausage and Brain Heart Infusion broth (BHIB), with and without additives were also inoculated with S. aureus and held at 4C. Samples of ground beef and sausage were examined for S. aureus, aerobic plate count and pH values. The numbers of S. aureus cells were decreased by 1.64 and 2.02 log units in ground beef held at 4C after 7 days and -27C after 7 weeks, respectively. A decrease in the number of S. aureus cells was observed in sausage and BHIB with addition of 0.5% trisodium phosphate (TSP), 78 mg/kg sodium nitrate, 78 mg/kg sodium nitrate plus 156 mg/kg sodium nitrate and 78 mg/kg sodium nitrite plus 0.5% TSP. Overall, sodium nitrite either alone or in combination with sodium nitrate was more effective on S. aureus and aerobic bacteria than TSP either alone or in combination with sodium nitrite.