Effects of dietary inclusion of sunflower soap stocks on colour,oxidation and microbiological growth of meat from light fattening lambs

Thirty-two lambs were finished on a total mixed ration (TMR) pelleted alone (00SS) or including sunflower soap stock (SS): 15SS (15 g SS per kg TMR), 30SS (30 g SS per kg TMR) and 60SS (60 g SS per kg TMR). Lambs (8 per group) were slaughtered at 27 kg live weight. Colour evolution, lipid oxidation, microbial growth and detection of diarrhoeagenic Escherichia coli were studied in meat samples. SS in the diet reduced meat lipid oxidation (P < 0.05), but had no significant effect (P > 0.05) on the cholesterol oxidation products. Meat from 60SS and control animals (00SS) revealed greater discoloration (P < 0.05) than 15SS. SS supplementation did not affect the microbiological populations, whereas high doses of SS seemed to increase the proliferation of diarrhoeagenic E. coli on day 14 (P < 0.10). These results suggest that the rate of SS inclusion in the diet of fattening lambs should not be above 15 g SS per kg TMR.     

Effect of low-temperature preservation on quality changes in Pacific white shrimp,Litopenaeus vannamei: a review

Shrimp has been widely accepted as an excellent resource for white meat due to its high-protein and low-fat content, especially low cholesterol. However, shrimps are highly perishable during preservation and retailing procedures due to the activities of enzymatic proteolysis, lipid oxidation, and microbial degradation. With increasing knowledge of and demands for safety, nutrition, and freshness of shrimp products, energy efficient, quality, maintained, and sustainable preservation technologies are needed. Low-temperature preservation, a practical processing method for improving the shelf life of food products, is widely used in the aquatic industry. This review focuses on the effects of low-temperature preservation on the quality changes in Litopenaeus vannamei. It considers physicochemical properties, sensory evaluation, melanosis assessment, and microbiological analysis. The perspectives of non-protein-based techniques on quality analysis of shrimps during preservation are also discussed. © 2019 Society of Chemical Industry     

湛江地区养殖南美白对虾冷藏期间的菌相分析及优势腐败菌的初步鉴定

将湛江地区养殖的南美白对虾在(4±1)℃条件下进行冷藏保鲜,通过细菌形态观察和生理生化实验对冷藏不同时期的细菌组成进行了定性和定量研究,并对优势腐败菌进行了初步鉴定。结果表明:湛江地区养殖的南美白对虾冷藏初期的细菌总数为2.8×104CFU/g,由10个属的细菌组成,其中有6个属为G-,且它们的数量占细菌总数的80%,其中以黄杆菌和气单胞菌的数量最多,分别占细菌总数的33.3%和13.3%;冷藏的第2天为高品质期,细菌总数为5.1×104CFU/g,黄杆菌(30%)和不动杆菌(16.7%)的数量最多,G-的数量增长到86.7%;随着冷藏时间的延长,细菌种类逐渐减少,货架期终点时细菌总数为3.0×106CFU/g,但只分离到8个属的细菌,其中G-占93.4%,气单胞菌和假单胞菌的数量均增加到16.7%,而黄杆菌减少为26.7%,其他种类的G-均有不同程度的增长。冷藏至第6天,细菌总数高达2.4×107CFU/g,虾肉完全腐败变质,从中分离获得的4个属的优势腐败菌均为G-,它们分别是黄杆菌、希瓦氏菌、假单胞菌和气单胞菌,各自所占比例为28.74%、26.44%、21.84%和16.09%。     

Shelf‐life characteristics of fresh oysters and ground beef as affected by bacteriocin‐coated plastic packaging film

Fresh oysters and ground beef were wrapped in antimicrobial films coated with a bacteriocin (nisin or lacticin NK24) incorporated into a polyamide binder layer. The packaged foods were stored at 3 and 10 °C and changes in counts of total aerobic bacteria and coliform bacteria were monitored together with appropriate quality attributes in order to determine the influence of the bacteriocin‐coated films on quality preservation and shelf‐life extension. Compared to plain low‐density polyethylene film, plastic films with incorporated bacteriocins slowed down microbial growth on packaged oysters and ground beef at both temperatures, contributed in some degree to the preservation of chemical quality and extended shelf‐life significantly. The effects of the antimicrobial films on the suppression of coliform bacterial growth were more pronounced at 10 than at 3 °C , while the effects on total aerobic bacteria were consistently evident at both temperatures. There was no difference in food quality preservation between the two types of antimicrobial film. © 2002 Society of Chemical Industry     

冷链条件下气调包装酱卤鸭肉制品货架期预测模型的建立

目的 以气调包装酱卤鸭肉制品为研究对象,在冷链温度范围内建立一套准确、高效的货架期预测模型。方法 利用选择性培养基测定不同温度下产品各微生物数量,确定4~25℃条件下产品优势腐败菌。对乳酸菌数量与感官评定值进行了回归分析确定最小腐败量Ns。分别采用修正的Gompertz方程和平方根方程建立一、二级模型,并通过预测值与实测值对比验证模型的可靠性。结果 确定了4~25℃条件下产品优势腐败菌为乳酸菌,最小腐败量Ns=6.14(lg(cfu /g))。一、二级模型拟合度均良好,三种温度下模型预测值与实际值间的差异均在30％左右,波动幅度在10%以内。结论 实现了对4~25℃内任何时间点产品剩余货架期的预测,为冷链条件下气调包装酱卤鸭肉制品品质的变化提供了理论指导。     

水果腐败关键病原微生物检测研究进展

果蔬病害腐败会导致严重的经济耗损,不仅会影响经济效益,也会损失水果中果胶、蛋白质等营养成分,人食用含有致病微生物的腐败水果后也会引发一系列疾病。造成水果腐败的关键致病微生物主要为霉菌及酵母菌,霉菌主要有葡萄孢属(Botrytis)、青霉属(Penicillium)和链格孢属(Alternaria),酵母菌主要包括掷孢酵母属(Sporobolomyces)、梅奇酵母属(Metschnikowia)。其中,霉菌占有主要地位,造成食品腐败变质的霉菌以青霉属为主。目前,检测水果腐败的关键致病微生物的方法主要包括分子生物学方法、生化检测技术、依靠代谢组学的检测方法以及免疫学技术等。研究拓展关于水果腐败的关键致病微生物的检测方法,对于预防控制水果病害及提高水果产出质量都有十分重要的意义。本文主要介绍引起水果腐败的关键致病微生物的形态及其适宜生长条件,同时着重论述检测腐败水果中关键致病微生物的方法。     

Pre rigor processing,ageing and freezing on tenderness and colour stability of lamb loins

Forty eight lamb carcasses with temperature and pH monitored were obtained from two commercial plants. At 24 h post mortem both loins (M. longissimus) from each carcass were randomly allocated to a) unaged frozen at − 18 °C, (b) aged at − 1.5 °C for 2 weeks before freezing, (c) aged for 3 weeks before freezing and (d) aged for 9 weeks without freezing. Shear force, colour stability and proteolysis were analyzed. Carcasses with a slower temperature and more rapid pH decline had more calpain autolysis, slightly higher shear force and less colour stable compared to that counterpart in general (P < 0.05). However, the shear force values of the loins were all acceptable (< 6 kgF) regardless of different pre rigor processing and ageing/freezing treatments. Furthermore, the loins aged for 2 weeks-then-frozen/thawed had a similar shear force to the loins aged only for 9 weeks suggesting that ageing-then-freezing would result in equivalent tenderness compared to aged only loins for the long-term storage.     

Inhibition of Fungal Growth on Wheat and Rye Bread by Modified Atmosphere Packaging and Active Packaging Using Volatile Mustard Essential Oil

ABSTRACT: Wheat and rye bread artificially inoculated with molds were packed in modified atmospheres of 0%, 50%, 75%, or 100% CO₂ balanced with N₂, and 3 levels of residual O₂, 1%, 0.03%, or <0.01%/O₂-absorber, and stored for 30 to 35 d. Modified atmosphere packaging (MAP) was quantitatively more effective for rye bread because fewer mold species grew at elevated CO₂. However, the major rye bread contaminant, Penicillium roqueforti , was the overall most CO₂-resistant mold and only the use of O₂-absorber could prevent growth of this species. On wheat bread, the most CO₂-tolerant mold was Penicillium commune , growing in 99% CO₂ (with high residual O₂), and Aspergillus flavus was the mold species that grew at lowest O₂ in 75% CO₂ treatment. The spoilage yeast/"chalk mold" Endomyces fibuliger was less affected by the different O₂ levels than the true filamentous molds, and none of the tested MAP treatments could prevent growth, but lag-phase was increased with O₂-absorber on wheat bread and decreased with 1% residual O₂ on rye bread. Experiments with volatile mustard oil showed that A. flavus and Eurotium repens were the most mustard oil-resistant species on wheat and rye bread, respectively. A combination strategy with MAP and mustard oil proved most optimal, and total inhibition was achieved with 2 μL mustard oil/rye bread slice and between 2 and 3 μL/wheat bread. Results indicated that the nature and surface area of the product influences effectiveness of active packaging with mustard oil.     

Effect of information about animal welfare, expressed in terms of rearing conditions, on lamb acceptability

The present study was aimed to assess the effect of information about the farming system and welfare of artificially (AR) and ewe-reared lambs (ER) on meat acceptability. An 84-consumer panel was asked to give three types of evaluation for both products: tasting without information (perceived liking); information without tasting (expected liking); tasting with information (actual liking). For both products, the expected liking was significantly different from the perceived liking (P<0.001), thus indicating that a disconfirmation occurred. The consumers found ER meat worse than expected (negative disconfirmation) and AR meat better than expected (positive disconfirmation). No significant difference between perceived and actual liking was observed for ER lamb (P>0.05), whereas, for the meat produced by AR lambs actual liking was lower than perceived liking (P<0.001). However, consumers did not completely assimilate their liking in the direction of expectations, as indicated by the fact that expectancy for AR lamb was significantly lower than actual acceptability (P<0.001). Mean scores of perceived liking were higher for the meat produced by AR animals as compared to ER lambs (P<0.05). Conversely, expected and actual liking scores were higher for meat from ER lambs than for meat from AR animals (P<0.001 and P<0.05, respectively). These results show that information about animal welfare, expressed in terms of rearing conditions, can be a major determinant of animal-based food acceptability, thus providing a potential tool for meat differentiation.