Effect of muscle,ageing time and modified atmosphere packaging conditions on the colour,oxidative and microbiological stability of packed beef

The objective of this study was to evaluate the influence of two different vacuum ageing times (7 and 14 days) and the impact of the modified atmosphere packaging (MAP) configuration (gas/product ratios: 0.5 and 1 and gas composition: 70% O₂ + 30% CO₂ and 40% O₂ + 30% CO₂ + 30% N₂) on the quality of fresh beef during subsequent storage at 4 °C. For this purpose, three separate experiments were performed. For each experiment, two different muscles (Longissimus dorsi and Biceps femoris) were sampled from four double‐muscled Belgian Blue beef carcasses. Next to colour, also the evolution in microbial load, pH, O₂ and CO₂ in the headspace and lipid oxidation at the meat surface were evaluated. A vacuum ageing for 14 days compared with 7 days resulted in a higher initial microbial load on the day of MAP packaging, which resulted finally in a significantly shorter shelf life. This ageing effect was less pronounced on the colour stability and lipid oxidation of the meat samples. No significant influence of the packaging configuration on any of the analysed parameters (colour, microbial load, pH and lipid oxidation at the meat surface) was observed.     

SAFARI engineering model 50 mK cooler

SAFARI is an infrared instrument developed by a European based consortium to be flown in SPICA, a Japanese led mission. The SAFARI detectors are transition edge sensors (TES) and require temperatures down to 50 mK for their operation. For that purpose we have developed a hybrid architecture based on the combination of a 300 mK sorption stage and a small adiabatic demagnetization stage. An engineering model has been designed to provide net heat lifts of 0.4 and 14 μW respectively at 50 and 300 mK, with an overall cycle duration of 48 h and a duty cycle objective of over 75%. The cooler is self-contained, fits in a volume of 156 × 312 × 182 mm and is expected to weigh 5.1 kg. It has been designed to withstand static loads of 120 g and a random vibration level of 21 g RMS.     

Levels of microbial contamination of domestic refrigerators in Italy

AimAccording to the EFSA Report 2013, 32.7% of outbreaks of foodborne illness registered in Europe occurs within the home, due to inadequate hygienic behaviour of consumers when preparing foods in the kitchen. The efficacy of proper cleaning of cutting boards, dishes and cutlery in limiting microbial cross-contaminations in the kitchen has been documented many times, whereas few researches have been performed to determine the microbial load of the internal walls of domestic refrigerators, in Italy. The aim of this investigation is to ascertain the role played by internal surfaces of home refrigerators as possible sources of microbial contamination of foods.Material and methodsWe analyzed 293 domestic refrigerators of students or workers at the university campus of Agripolis (Legnaro, Italy). For each refrigerator, 2 internal surfaces were sampled using sponge-bags. The amounts of total viable count (TVC), Gram-negative spoiling bacteria, moulds and yeasts and the main pathogenic bacterial species were determined.ResultsTVCs greater than 1 log CFU cm⁻² are in a little over 50% of the samples analyzed and are found mainly on the bottom of the refrigerator (61%) compared to the walls (39%) (P < 0.001). Even for other microbial counts the risk ratio of finding them on the bottom of the refrigerator is significantly higher than on the walls; the possibility of there being a finding on the bottom with respect to the walls varies from 2.5 to 8.5 times respectively for moulds and Aeromonas spp. Salmonella spp. was found in 1.7% of the samples, Bacillus cereus in 5.6%, Coagulase-positive staphylococci (CPS) in 4%, the prevalence of which is always higher on the bottom of the refrigerator. Listeria monocytogenes and Yersinia enterocolitica were never found.ConclusionsIt is necessary to better educate consumers to clean their appliances more frequently.     

Thermodynamic performance of the 3-stage ADR for the Astro-H Soft-X-ray Spectrometer instrument

The Soft X-ray Spectrometer (SXS) instrument (Mitsuda et al., 2010) [1] on Astro-H (Takahashi et al., 2010) [2] will use a 3-stage ADR (Shirron et al., 2012) to cool the microcalorimeter array to 50 mK. In the primary operating mode, two stages of the ADR cool the detectors using superfluid helium at ⩽1.20 K as the heat sink (Fujimoto et al., 2010). In the secondary mode, which is activated when the liquid helium is depleted, the ADR uses a 4.5 K Joule–Thomson cooler as its heat sink. In this mode, all three stages operate together to continuously cool the (empty) helium tank and single-shot cool the detectors. The flight instrument – dewar, ADR, detectors and electronics – were integrated in 2014 and have since undergone extensive performance testing. This paper presents a thermodynamic analysis of the ADR’s operation, including cooling capacity, heat rejection to the heat sinks, and various measures of efficiency.     

Microbial Diversity of Ground Beef Products in South Korean Retail Market Analyzed by PCR-DGGE and 454 Pyrosequencing

The purpose of this study was to assess the microbial community in ground beef purchased from local stores in the north central area of South Korea. A total of 31 ground beef samples showed 3.77 ± 5.16 × 10⁵ CFU/g on aerobic plate counts, and PCR-based denaturing gradient gel electrophoresis was performed to assess the microbial community, which revealed a diverse profile among the products. Four of these samples were selected for further analyses via 454 pyrosequencing. Pseudomonas was the most frequently identified genus in terms of relative abundance (4.54–73.8%), and other bacteria such as Lactobacillus, Acinetobacter, and Carnobacterium were also identified in the ground beef. The presence of bacteria can affect the spoilage of ground beef products depending on the microbial populations, and understanding these populations may help limit spoilage and/or foodborne illness. This study illustrates the microbial diversity occurring among Korean ground beef products, even within a local region, and provides a molecular approach for potential ground beef microbial quality assessment.     

Improvement of tenderness and water holding capacity of spiced beef by the application of ultrasound during cooking

The aim of this study was to assess the effects of power ultrasound‐assisted (0, 400, 600, 800 and 1000 W, frequency of 20 kHz) cooking (80, 100, 120 min) on spiced beef. The results showed that power ultrasound could significantly increase the salt content (P < 0.05). For water holding capacity, the ultrasonic treatment could significantly reduce the pressure loss and free water content while improving the immobilised water content (P < 0.05). And ultrasonic treatment improved hardness compared with control (P < 0.05). However, the effects on the springiness, the chewiness and the resilience of the spiced beef were not significant (P > 0.05). As for microstructure, the myofibrils of beef were ruptured by ultrasonic treatment along with the Z‐lines leading to the muscle swelling. The results indicated that the application of ultrasound during cooking could effectively promote the penetration of salt, improve the water holding capacity and ameliorate the tenderness of spiced beef.     

牛肉、牛奶中可的松和氢化可的松含量分析

采用液相色谱-串联质谱技术分析我国部分地区市售牛肉、牛奶中可的松和氢化可的松的含量水平。均质的牛肉或牛奶样品在乙酸-乙酸钠缓冲液中酶解后用甲醇提取，提取液用石墨化碳黑固相萃取小柱和氨基固相萃取小柱净化，洗脱液氮吹至干并用甲醇溶液定容，液相色谱-串联质谱测定。采用SPSS?21.0软件进行数据分析。对采自我国9?省市的346?份牛肉和牛奶样品进行检测，分析牛肉和牛奶中可的松和氢化可的松的存在水平。牛肉和牛奶中均检出可的松和氢化可的松，检出率在86.1%～100.0%之间，检出含量范围为0.02～74.88?μg/kg。牛肉中可的松和氢化可的松的含量平均值（中位数）分别为1.69（1.14）?μg/kg和12.16（8.14）?μg/kg，牛奶中可的松和氢化可的松的含量平均值（中位数）分别为0.23（0.23）?μg/kg和0.72（0.72）?μg/kg。牛肉和牛奶中氢化可的松与可的松的含量均呈显著正相关。