raw-milk cheese

  • 文章类型: Journal Article
    发酵食品,包括奶酪,近年来,它们对健康的潜在益处越来越感兴趣。本研究探讨了八种法国生乳奶酪-山羊奶酪的生物学特性,圣Nectaire,Cantal,布鲁·奥弗涅,Roquefort,Comté,BriedeMeaux,和使用体内(秀丽隐杆线虫)和体外(人白细胞)模型的Epoises-on氧化过程。对奶酪分馏方案进行了调整,以研究每种奶酪的四个馏分:对应于整个奶酪的冻干馏分(FDC),极地(ApE),和两种极性提取物(W40和W70)。我们表明,所有奶酪级分都显着改善了秀丽隐杆线虫(C.秀丽隐杆线虫)暴露于氧化条件时的存活率是对照组的五倍,无论分馏方案和奶酪类型。它们还能够在氧化条件下将体内活性氧(ROS)的积累减少多达70%,从而保护秀丽隐杆线虫免受氧化损伤。这些有益作用可通过人白细胞中体外ROS产生的减少高达50%以及C中抗氧化因子编码基因(daf-16,skn-1,ctl-2和sod-3)的过表达来解释。
    Fermented foods, including cheeses, have garnered increased interest in recent years for their potential health benefits. This study explores the biological properties of eight French raw-milk cheeses-goat cheese, Saint-Nectaire, Cantal, Bleu d\'Auvergne, Roquefort, Comté, Brie de Meaux, and Epoisses-on oxidative processes using both in vivo (Caenorhabditis elegans) and in vitro (human leukocytes) models. A cheese fractionation protocol was adapted to study four fractions for each cheese: a freeze-dried fraction (FDC) corresponding to whole cheese, an apolar (ApE), and two polar extracts (W40 and W70). We showed that all cheese fractions significantly improved Caenorhabditis elegans (C. elegans) survival rates when exposed to oxidative conditions by up to five times compared to the control, regardless of the fractionation protocol and the cheese type. They were also all able to reduce the in vivo accumulation of reactive oxygen species (ROS) by up to 70% under oxidative conditions, thereby safeguarding C. elegans from oxidative damage. These beneficial effects were explained by a reduction in ROS production up to 50% in vitro in human leukocytes and overexpression of antioxidant factor-encoding genes (daf-16, skn-1, ctl-2, and sod-3) in C. elegans.
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  • 文章类型: Journal Article
    生乳的微生物种群在生乳奶酪的独特特性的发展中起着至关重要的作用,特别受到消费者的赞赏。先前已证明,通过在39°C下进行的高速离心(也称为细菌发酵)来改变原料奶的微生物种群。本研究的目的是评估这一过程的效果,执行一次或两次,微生物,组成,生物化学,和衍生的硬质奶酪的感官特征。在13个月的时间内,在奶酪工厂并行进行了实验和对照奶酪制作。在成熟9、15和20个月后对奶酪进行微生物计数分析,composition,蛋白水解程度,挥发性化合物,和感官轮廓。结果表明,相对于对照,实验干酪的特征在于活的乳杆菌数量较低。实验奶酪还显示了初级和次级蛋白水解过程的差异,反过来,在所有成熟时间导致不同模式的游离氨基酸。实验奶酪的酯含量明显较低,并且评估人员在某些性状上与对照区分开。总之,如果原料奶奶酪的特性,则应禁止使用牛奶的高速离心,尤其是PDO奶酪,想要被保留。
    The microbial population of raw milk plays a crucial role in the development of distinctive traits of raw-milk cheeses particularly appreciated by consumers. It was previously demonstrated that the microbial population of raw milk is modified by a high-speed centrifugation (also called bactofugation) conducted at 39 °C. The aim of the present study was to evaluate the effects of this process, performed once or twice, on the microbial, compositional, biochemical, and sensory characteristics of the derived hard cheeses. Experimental and control cheesemaking were conducted in parallel at a cheese factory during a 13-month period. Cheeses were analysed after 9, 15 and 20 months of ripening for microbial count, composition, proteolysis extent, volatile compounds, and sensory profile. Results evidenced that experimental cheeses were characterized by lower numbers of viable lactobacilli respect to control. Experimental cheeses also showed differences in the progress of primary and secondary proteolysis which, in turn, caused different patterns of free amino acids at all ripening times. Experimental cheeses had significantly lower content of esters and were differentiated from control for some traits by assessors. In conclusion, use of high-speed centrifugation of milk shall be discouraged if characteristic traits of raw-milk cheeses, particularly PDO cheeses, want to be retained.
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  • 文章类型: Journal Article
    本研究的目的是表征来自生乳奶酪的LAB分离株,评估它们的一些技术特性,并选择一些可能用作发酵剂培养物的“野生实验室”菌株。从原料奶中分离并鉴定了LAB菌株,凝乳,和奶酪在30、60和90天成熟。共分离出100株,20从每个成熟阶段。对所有分离物进行酸化能力测试,凝乳形成,以及在24和48小时后在32°C和42°C下产生的香气。在酸化测试之后,选择42个菌株进行鉴定和表征其技术特性。在整个奶酪制作过程中发现了高比例的乳酸菌和革兰氏球菌。肠球菌在成熟的第7天达到最大比例,而乳杆菌在成熟的第一个月显着增加。通过表型鉴定了42株,生物化学,和分子技术。乳球菌在生乳和凝乳中占主导地位,而乳杆菌在奶酪的成熟中占主导地位。四个LAB菌株,包括一个假肠列明串珠菌,两个副干酪乳杆菌亚种。副干酪和一个希雷肠球菌,被提议作为初学者或次生文化的潜在用途。
    The aim of the present study was to characterize LAB isolates from raw-milk cheeses, to evaluate some of their technological properties and to select a few \'wild\' LAB strains that could potentially be used as starter cultures. LAB strains were isolated and identified from raw milk, curd, and cheese at 30, 60, and 90 days of ripening. A total of 100 strains were isolated, 20 from each phase of ripening. All isolates were tested for acidification ability, curd formation, and aroma production at 32 °C and 42 °C after 24 and 48 h. Following the acidification test, 42 strains were selected for identification and characterization of their technological properties. A high proportion of lactic acid bacteria and Gram + cocci were found throughout the cheese-making process. Enterococci reached their maximum proportion on the 7th day of ripening while Lactobacilli increased significantly during the first month of ripening. Forty-two strains were identified by phenotypic, biochemical, and molecular techniques. Lactococci were predominant in raw milk and curd while Lactobacilli in the ripening of the cheese. Four LAB strains including one Leuconostoc pseudomenteroides, two Lacticaseibacillus paracasei subsp. paracasei and one Enterococcus hirae, were proposed for their potential use as starters or secondary cultures.
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  • 文章类型: Journal Article
    Certain cheeses can be legally produced in the United States using raw milk, but they must be aged for at least 60 d to reduce pathogen risks. However, some varieties, even when aged for 60 d, have been shown to support growth of Listeria monocytogenes or survival of Shiga toxin-producing Escherichia coli (STEC). Thermization, as a subpasteurization heat treatment, has been proposed as a control to reduce the risk of pathogens in raw cheese milk while retaining some quality attributes in the cheese. However, the temperature and time combinations needed to enhance safety have not been well characterized. The objective of this research was to determine and validate decimal reduction values (D-values) for L. monocytogenes and STEC at thermization temperatures 65.6, 62.8, and 60.0°C; a D-value at 57.2°C was also determined for L. monocytogenes only. Nonhomogenized, pasteurized whole-milk samples (1 mL) were inoculated with 8-log cfu/mL L. monocytogenes or STEC (5- or 7-strain mixtures, respectively), vacuum-sealed in moisture-impermeable pouches, and heated via water bath submersion. Duplicate samples were removed at appropriate intervals and immediately cooled in an ice bath. Surviving bacteria were enumerated on modified Oxford or sorbitol MacConkey overlaid with tryptic soy agar to aid in the recovery of heat-injured cells. Duplicate trials were conducted, and survival data were used to calculate thermal inactivation rates. D65.6°C-, D62.8°C-, and D60.0°C-values of 17.1 and 7.2, 33.8 and 16.9, and 146.6 and 60.0 s were found for L. monocytogenes and STEC, respectively, and a D57.2°C-value of 909.1 s was determined for L. monocytogenes. Triplicate validation trials were conducted for each test temperature using 100 mL of milk inoculated with 3 to 4 log cfu/mL of each pathogen cocktail, A 3-log reduction of each pathogen was achieved faster in larger volumes than what was predicted by D-values (D-values were fail-safe). Data were additionally compared with published results from 21 scientific studies investigating L. monocytogenes and STEC in whole milk heated to thermization temperatures (55.0-71.7°C). These data can be used to give producers of artisanal raw-milk cheese flexibility in designing thermal processes to reduce L. monocytogenes and STEC populations to levels that are not infectious to consumers.
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  • 文章类型: Journal Article
    Many studies have highlighted the relationship between food and health status, with the aim of improving both disease prevention and life expectancy. Among the different food groups, fermented foods a have huge microbial biodiversity, making them an interesting source of metabolites that could exhibit health benefits. Our previous study highlighted the capacity of raw goat milk cheese, and some of the extracts recovered by the means of chemical fractionation, to increase the longevity of the nematode Caenorhabditis elegans. In this article, we pursued the investigation with a view toward understanding the biological mechanisms involved in this phenomenon. Using mutant nematode strains, we evaluated the implication of the insulin-like DAF-2/DAF-16 and the p38 MAPK pathways in the phenomenon of increased longevity and oxidative-stress resistance mechanisms. Our results demonstrated that freeze-dried raw goat milk cheese, and its extracts, induced the activation of the DAF-2/DAF-16 pathway, increasing longevity. Concerning oxidative-stress resistance, all the extracts increased the survival of the worms, but no evidence of the implication of both of the pathways was highlighted, except for the cheese-lipid extract that did seem to require both pathways to improve the survival rate. Simultaneously, the cheese-lipid extract and the dried extract W70, obtained with water, were able to reduce the reactive oxygen species (ROS) production in human leukocytes. This result is in good correlation with the results obtained with the nematode.
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