Effect of hot-boned pork on the keeping quality of fresh pork sausage

The first experiment evaluated the effect of solid carbon dioxide (dry ice) addition to hot-boned meat, in different proportions, upon the keeping quality of fresh pork sausage patties. Dry ice had some negative effects at levels of 20% to 40%, such as hardening and colour fading of samples, although it increased water-holding capacity of the sausage. In the second experiment three proportions of hot-boned meat and chilled meat were evaluated as a means to extend the retail storage time of fresh pork sausage links. Hot-boned pork was treated by three methods: freezing the meat before grinding, salting and freezing, and salting plus dry ice addition. The results favoured the use of 50% hot-boned meat and 50% chilled meat, for which the lowest hardness and oxidation values were obtained. Microbial counts and hue values showed no significant variation among the three treatments. Salting and freezing hot-boned meat before grinding was the method which produced the best overall quality.     

溶菌酶对草莓的保鲜效果

应用溶菌酶对草莓进行保鲜,结果表明,在２０℃单独使用溶菌酶不如与甘氨酸复合使用效果;同时离子强度、ｐＨ值对结果有影响。最后得出最佳配比：溶菌酶０．０７％,氯化钙０．５％,甘氨酸１．５％     

Prevalence of microbial biofilms on selected fresh produce and household surfaces

Investigations of biofilms in domestic environments are sparsely represented in the literature. In this study, samples of various household surfaces, including food, laundry and kitchen items, were analyzed for evidence of biofilm presence. Visualization of the surfaces was carried out using cryostage scanning electron microscopy (CSEM) and light microscopy. Qualitative evidence of the presence of biofilm formation was obtained from all of the sample groups analyzed, suggesting the widespread existence of microorganisms in biofilms on domestic surfaces. This suggests that biofilms may be important in household hygiene, and highlights the need for standardized, approved biofilm methods suitable for consumer products testing.     

Effect of cold plasma on insect infestation and keeping quality of stored wheat flour

Cold plasma has been applied as an alternative technology for pest control of stored commodities. Wheat flour is infested with three different insect species and subjected to plasma treatment at two power levels (40 W and 60 W) with three-time intervals. Further, the growth of larvae and pupae of insects was examined at different storage periods by sieving and visual inspection methods. There was a significant increase in the death of larvae and pupae of insects. Iodine and bromocresol green staining tests were used to detect the eggs in the flour. The parameters related to the quality of flour during the storage, like lipase enzyme activity and oxidation of fats, were analyzed. A decrease in lipase enzyme activity by 35% on the 90th days was observed in 60 W-30 min treated samples. The reduction in lipase enzyme activity resulted in a lower Thiobarbituric acid value. No significant change was observed in the color profile of wheat flour after the plasma treatment. This study shows that cold plasma can be applied as a novel technology for pest control management to enhance stored food product quality.     

Maintaining postharvest quality of fresh produce with volatile compounds

The postharvest quality of strawberry (Fragaria ananassa Duch.) and tomato (Lycopersicon esculentum L.) fruit was evaluated after treatment with eucalyptus (Ec: Eucalyptus globulus L.) and cinnamon (Cn: Cinnamomum zeylanicum, Blume) volatile oil compounds and storage at 13 °C during or following vapour exposure. Fruit decay decreased in fruit treated with oil vapours and transfer to ‘ambient air’ (AA). Cn-treated tomato maintained fruit firmness during exposure, but the effects were not persistent following storage to AA. However, no effects on fruit firmness were observed for Ec-treated tomato and strawberry-treated with Ec-and Cn-vapours. Oil vapours stimulated levels of total soluble solids during exposure but effects were persistent only for ‘cherry’ tomatoes following exposure. Fruit samples treated with oil vapours did not differ in percentage weight loss, organic acid content, sweetness and total phenolic content during or following vapour exposure compared with untreated fruit. The results suggest that essential oil vapour may improve fruit quality-related attributes on top of the well-documented antimicrobial protection during fresh produce storage and transit.     

大蒜提取液对香菇保鲜效果的影响

以香菇为原料,研究大蒜提取液对香菇保鲜的效果。以贮藏期间的呼吸强度、失重率、细胞膜透性、腐烂指数和感官评价为测定项目,研究了不同浓度的大蒜提取液对香菇的保鲜效果。结果表明不同浓度的大蒜提取液都能抑制香菇的呼吸强度、失重率、细胞膜透性和腐烂指数,降低香菇外观品质的变化,有效延缓香菇衰老腐败。不同浓度的大蒜提取液对香菇保鲜的效果由大到小顺序为:料液比(g:mL)1:5>料液比(g:mL)1:10>料液比(g:mL)1:15>料液比(g:mL)1:20。     

A field study of the microbiological quality of fresh produce

The Centers for Disease Control and Prevention has reported that foodborne disease outbreaks associated with fruits and vegetables increased during the past decade. This study was conducted to characterize the routes of microbial contamination in produce and to identify areas of potential contamination from production through postharvest handling. We report here the levels of bacterial indicator organisms and the prevalence of selected pathogens in produce samples collected from the southern United States. A total of 398 produce samples (leafy greens, herbs, and cantaloupe) were collected through production and the packing shed and assayed by enumerative tests for total aerobic bacteria, total coliforms, total Enterococcus, and Escherichia coli. These samples also were analyzed for Salmonella, Listeria monocytogenes, and E. coli O157:H7. Microbiological methods were based on methods recommended by the U.S. Food and Drug Administration. For all leafy greens and herbs, geometric mean indicator levels ranged from 4.5 to 6.2 log CFU/g (aerobic plate count); less than 1 to 4.3 log CFU/g (coliforms and Enterococcus); and less than 1 to 1.5 log CFU/g (E. coli). In many cases, indicator levels remained relatively constant throughout the packing shed, particularly for mustard greens. However, for cilantro and parsley, total coliform levels increased during the packing process. For cantaloupe, microbial levels significantly increased from field through packing, with ranges of 6.4 to 7.0 log CFU/g (aerobic plate count); 2.1 to 4.3 log CFU/g (coliforms); 3.5 to 5.2 log CFU/g (Enterococcus); and less than 1 to 2.5 log CFU/g (E. coli). The prevalence of pathogens for all samples was 0, 0, and 0.7% (3 of 398) for L. monocytogenes, E. coli O157:H7, and Salmonella, respectively. This study demonstrates that each step from production to consumption may affect the microbial load of produce and reinforces government recommendations for ensuring a high-quality product.     

减压处理对水蜜桃保鲜效果的影响

以"湖景"水蜜桃为材料,常压冷藏处理为对照,研究1.5k Pa((3±1)℃)减压处理20d和减压预处理12、24h后常压冷藏至20d,再置于常压(25±1)℃中5d对水蜜桃品质变化的影响。结果表明:在(3±1)℃低温下,贮藏20d后,减压处理20d组效果最为显著(p0.05),失重率和相对电导率最低,呼吸受到抑制,VC和可滴定酸下降缓慢,货架期最长5d以上。同时,12h减压预处理对提高水蜜桃保鲜品质的效果略好于24h减压预处理,都显著(p0.05)优于常压对照。减压处理及减压预处理都具有良好的保鲜效果,而减压预处理能极大节约成本,更利于推广应用。     

不同浓度CO2对箱式气调贮藏树莓保鲜效果的影响

以Heritage品种树莓作为试验材料,采用塑料气调保鲜箱,通过分析贮藏过程中箱内O2、CO2气体、果实感官及主要生化指标的变化,研究了不同体积分数CO2对树莓鲜果贮藏保鲜效果的影响。结果表明:CO2处理对箱式气调贮藏树莓的保鲜效果具有一定影响,其中,CO2体积分数为5%的处理,贮藏过程中箱内CO2和O2体积分数变化幅度均较小,果实PPO活性的升高和MDA的积累受到一定的抑制,果实POD活性维持了较高水平,贮藏至40d时果实色泽基本无变化,香气略变淡,仅个别果实表面有零星水珠出现。由此表明,CO2体积分数为5%更适宜树莓箱式气调贮藏,维持果实品质。     

减压处理对水蜜桃保鲜效果的影响

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Improved keeping quality of minimally fresh processed celery sticks by modified atmosphere packaging

Recommended storage conditions of green celery sticks are 4 °C for 10 days, but there are no reports about optimal modified atmosphere packaging (MAP) conditions to preserve them longer. The objective of this research was to describe the gas composition of MAP generated by two polymeric films and its effects on chemical, sensorial and microbial quality, and physiological disorders of celery sticks stored at 4 °C for 15 days. Green sticks of 15-cm length of ‘Trinova’ cv. were placed in hermetically sealed plastic bags: low-density polyethylene, oriented polypropylene (OPP) and polyethylene-perforated bags as control (air). The O₂ and CO₂ concentrations, soluble solid content, pH, titratable acidity, colour, sensorial quality and sugar and organic acids contents were monitored. Compared to the control, both MAP treatments improved the sensory quality, avoided the loss of green colour, decreased the development of pithiness and retarded the growth of microorganisms. In any treatment neither off-odours nor off-flavours were detected. After 15 days at 4 °C within the OPP bags a steady-state atmosphere of 6 kPa O₂+7 kPa CO₂ was reached and celery sticks stored under these bags showed the best quality.     

牛奶保鲜技术的研究进展

介绍了牛奶的营养成分及价值,综述了牛奶贮藏保鲜技术的研究进展,并结合实际情册蒡主要发展方向进行了展望。     

高湿冰箱温湿度控制性能及蔬菜保鲜效果研究

为了探讨不同冰箱内的温湿度变化及冰箱中贮藏蔬菜保鲜效果的差异,本文分析了美的冰箱BCD-642（高湿型）和BCD-252（普通型）冷藏室内的温湿度变化规律,并研究了2种冰箱冷藏室内菠菜和韭菜的贮藏品质和气味的变化。结果表明,高湿型冰箱的温湿度控制性能良好,温度在3.2³.9℃之间变化,平均温度为3.5℃;湿度在90.3%⁹5.7%之间波动,平均湿度为93.0%。高湿度冰箱对减少菠菜和韭菜的蒸腾失水,保持蔬菜V_C含量,保持硬度作用明显,其中以降低失水率作用最为明显,贮藏12 d时,普通冰箱内菠菜、韭菜的失重率分别为高湿冰箱的1.5倍和1.6倍。利用电子鼻对两种处理蔬菜的气味分析表明,韭菜和菠菜在不同的贮藏时间之间的气味差异显著,大于同一贮藏时间下2种型号冰箱之间蔬菜的气味变化,说明贮藏时间的长短是影响韭菜、菠菜气味变化的主要因素,而2种冰箱间蔬菜气味也存在着差异,这与贮藏品质的变化相吻合。      

水分对生鲜肉品品质的影响

水分作为肉品原料中含量最多的化学组分,直接影响着肉品品质及贮藏特性。本文介绍了水分在生鲜肉中结合状态、水分在肉品贮藏过程中的流失过程以及水分活度对肉品贮藏的影响,并对肉品中水分的检测方法进行了综述。为快速检测肉品中水分、有效减少肉品贮藏过程中的水分散失、开发合理的生鲜肉品保鲜技术提供理论参考。      

纳米果蜡与1-甲基环丙烯复合处理对“台农”芒果保鲜效果的影响

以"台农"芒果为试材,分别在常温(25℃,RH=40%)和低温(13℃,RH=80%)下,对其进行芒果专用纳米硅基氧化物保鲜果蜡涂膜和新型乙烯拮抗剂1-甲基环丙烯(1-MCP)熏蒸处理。通过定期对芒果感官指标和生理指标的测定,结果表明:低温贮藏能有效地延缓芒果果实采后衰老,而不论是常温贮藏还是低温贮藏,果蜡涂膜与1-MCP熏蒸复合处理能显著地抑制芒果中水分的散失,降低腐烂率,延缓芒果果皮的转黄速度,抑制呼吸,并能够很好地保持果实风味和其中的营养品质,对芒果的保鲜效果最佳。     

短茎五加菜保鲜液加工技术的研究

短茎五加菜经原料选择、护绿、保鲜、装袋和杀菌等工序,加工成一种即食性小菜。采用正交试验极差分析研究了最佳的保鲜液配方,并分析了各因素的影响次序。     

HCF鸡蛋保鲜剂的研制及应用研究

对常用的几种涂膜保鲜剂做鸡蛋保鲜实验,综合鸡蛋减重率、蛋白指数、蛋黄指数和蛋黄pH四项指数,认为羧甲基壳聚糖的保鲜效果最好。HCF保鲜剂以羧甲基壳聚糖为主剂,辅以两种以上助剂组成。用HCF保鲜剂涂膜鸡蛋放入聚乙烯薄膜袋内,在实验室温度9～24℃,相对湿度50%～60%贮存149d,好蛋率占85%,散黄率占10%,变质率占5%,减重5%。     

壳聚糖复合涂膜对草莓保鲜的影响

迷迭香提取物、CaCl2、亚硫酸钠分别与壳聚糖复配涂膜研究草莓的贮藏保鲜技术,通过测定贮藏过程中草莓果实的营养成分、感官品质等指标,探究草莓在低温冷藏条件下的成熟衰老过程和不同保鲜剂处理对草莓贮藏品质的影响。结果表明:壳聚糖复配迷迭香提取物和壳聚糖复合CaCl2涂膜保鲜液均可显著地(P<0.05)减缓草莓的可溶性固形物、可滴定酸、Vc、还原糖含量的下降,抑制草莓细胞膜渗透率变化和果实的腐烂软化,保持草莓的硬度等贮藏品质。亚硫酸钠-壳聚糖处理可维持草莓的还原糖含量,延缓可滴定酸和Vc含量的下降。其中,1.5%壳聚糖+0.3%迷迭香提取物溶液浸渍涂膜5 min保鲜草莓效果最好,1.5%壳聚糖+2.0%CaCl2溶液浸渍涂膜5 min次之。     

干燥温度对玉米储存品质的影响

通过对4种高水分玉米样品在不同干燥温度下的品质进行研究分析表明,干燥温度对玉米的储存品质影响较大,在60℃时既能有效脱除水分,又能较好地保持储存品质.