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1.
The proteolytic and lipolytic changes during the ripening process were investigated in four batches of Armada goat's milk cheese (an artisanal variety produced in the North of Spain), by determining the classical nitrogen fractions, caseins and their degradation products, free amino acids, as well as the acidity of the fat, thiobarbituric acid (TBA) number and free fatty acids. Values obtained for the nitrogen fractions and for caseins and their degradation products show that this cheese undergoes very little protein degradation. A low free amino acids content was observed throughout the ripening process with a predominance of Pro followed by Leu+Ile, Glu acid, Phe, His+Lys and Val. The lipid degrada-tion was very intense from the second month of ripening, only comparable to that reported for cheeses ripened by moulds. The average free fatty acids content increased 20-fold during ripening, reaching final values of 44·5 g kg−1. All the free fatty acids increased considerably during ripening, resulting in a predominance of saturated and unsaturated long-chain acids, followed by medium-chain acids, C10 principally. Short-chain fatty acid content by the end of ripening was higher than that presented in other cheese varieties with a similar high degree of lipolysis. © 1997 SCI.  相似文献   

2.
《LWT》2002,35(3):222-232
Changes in the microbiological flora of Valdeteja, a ripened home-made raw goat's milk cheese produced in northwest Spain, were studied during the manufacture and ripening processes using the spiral plating method. High counts of all microbial groups were observed in milk (7.66, 7.57, 6.13, 6.91, 2.47, 5.18, 3.27 and 3.85 log10 cfu/g for aerobic mesophilic bacteria, lactococci, lactobacilli, leuconostocs, enterococci, Enterobacteriaceae,Micrococcaceae and moulds and yeasts, respectively). Counts increased between 0.76 and 1.96 log units from milk to curd. Lactic acid bacteria (lactococci, lactobacilli and leuconostocs) were the dominant microorganisms throughout ripening. Lactococci dominated over the lactobacilli up to day 27 of ripening. Leuconostocs were stable from day 2 of ripening. The final levels of typical enterococci were 3.62 log10 cfu/g. Aerobic mesophilic bacteria, Enterobacteriaceae andMicrococcaceae reached their maximum in curd and decreased significantly throughout ripening. The decrease ofEnterobacteriaceae was very marked, although they did not completely disappear at the end of the ripening process (2.74 log10 cfu/g). Moulds and yeasts counts increased significantly during ripening, giving final levels of 6.09 log10 cfu/g. A strong correlation (P<0.001) was found between pH and lactobacilli (R=−0.87), leuconostocs (R=−0.82) and moulds and yeasts (R=−0.74) and between aw and various microbial groups (e.g. EnterobacteriaceaeR=0.83).  相似文献   

3.
The objective of the present study was to investigate the influence of stretching temperature, fat content, and time of brining on proteolysis during ripening of Mozzarella cheeses. Seventeen cheese-making experiments (batches) were carried out on an industrial scale on successive days, following the standard procedure with some modifications. Fat content of cheese milk, temperature at the stretching step, and time of brining varied from one batch to another as required by the experimental design, outlined by a surface response model. Proteolysis was assessed during ripening of samples, which was prolonged for at least 3 mo, by means of electrophoresis, nitrogen fractions, and soluble peptide mapping. The amount of soluble nitrogen at pH 4.6 was not significantly different in cheeses obtained by diverse procedures, but it increased during ripening of all samples. This result was coincident with the breakdown of αs1- and β-caseins evidenced by electrophoresis, which reached similar extents at late stages of ripening, regardless of the cheese-making process. Multivariate analysis on soluble peptide profiles obtained by liquid chromatography also detected sample grouping according to ripening time, but did not evidence any separation caused by the cheese-making technology. We concluded that the changes in the cheese-making process assayed in this work were insufficient to produce significant differences in proteolysis of the cheeses. Ripening time had more influence on proteolysis of Mozzarella cheeses than any other assayed variable.  相似文献   

4.
ABSTRACT:  Cheddar cheese ripened at 8 °C was sampled at 7, 14, 28, 56, 112, and 168 d and subsequently used for the manufacture of processed cheese. The cheddar cheese samples were analyzed throughout ripening for proteolysis while the textural and rheological properties of the processed cheeses (PCs) were studied. The rate of proteolysis was the greatest in the first 28 d of cheddar cheese ripening but began to slow down as ripening progressed from 28 to 168 d. A similar trend was observed in changes to the texture of the PC samples, with the greatest decrease in hardness and increase in flowability being in the first 28 d of ripening. Confocal scanning laser microscopy showed that the degree of emulsification in the PC samples increased as the maturity of the cheddar cheese ingredient increased from 7 to 168 d. This increased emulsification resulted in a reduction in the rate of softening in the PC in samples manufactured from cheddar cheese bases at later ripening times. Multivariate data analysis was performed to summarize the relationships between proteolysis in the cheddar cheese bases and textural properties of the PC made therefrom. The proportion of α s 1-casein (CN) in the cheddar cheese base was strongly correlated with hardness, adhesiveness, fracturability, springiness, and storage modulus values for the corresponding PC. Degradation of α s 1-CN was the proteolytic event with the strongest correlation to the softening of PC samples, particularly those manufactured from cheddar cheese in the first 28 d of ripening.  相似文献   

5.
Proteolytic and lipolytic changes were studied throughout ripening of five batches of León cow's milk cheese, a traditional variety made in the north of Spain. Total soluble nitrogen, non-protein nitrogen, oligopeptides nitrogen, amino nitrogen and ammonia nitrogen fractions increased slightly during the ripening process. The final values of these nitrogen fractions indicate that this cheese undergoes a very slight proteolysis as much in extent as in depth. This weak protein degradation is corroborated when the caseins and their degradation products were quantified by electrophoresis. β-Casein stayed practically intact throughout the ripening process and only 10% of αs-casein became degraded. The content of total free amino acids increased progressively but in a slightly increased way during ripening, reaching final average values of 592 mg (100 g)−1 of total solids. The most abundant free amino acid at the end of ripening was lysine, followed by leucine, glutamic acid, tryptophan, valine and phenylalanine. The acidity index of the fat values increased during ripening by a factor of 4.39. The final values of this parameter are in the range of those observed in other cow's milk cheeses ripened by bacteria. The content in total free fatty acids underwent an increase throughout ripening reaching final average values of 6669 ppm. The most abundant free fatty acid at the end of ripening was oleic acid followed by butyric and palmitic acids. The high content of short-chain fatty acids is outstanding, specially that of butyric acid.  相似文献   

6.
《Journal of dairy science》2019,102(10):8721-8733
Bloomy rind cheeses, including Brie, Camembert, and related varieties, are at high risk of contamination by environmental pathogens during manufacture and ripening. This risk is particularly high during ripening due to open-air exposure of the product. Currently, no kill step is applied after manufacture or post ripening to control food safety risks associated with Listeria monocytogenes contamination. Instead, cheesemakers must rely on sanitation and environmental monitoring to reduce this risk. High-pressure processing (HPP) is a nonthermal food-processing technology that can effectively reduce bacterial contaminants with minimal impact on the organoleptic properties of various foods. The objective of this study was to evaluate HPP as a potential intervention to maintain Camembert cheese quality and reduce risk associated with L. monocytogenes. Timing of HPP treatments (3, 11, and 45 d after manufacture) was based on the growth of L. monocytogenes during Camembert cheese ripening. High-pressure processing treatment of fully ripened cheeses (45 d) resulted in destruction of the surface mold, which caused browning and yellowing of the cheese rind. Applying HPP treatment earlier in the ripening process (11 d) resulted in a similar degradation of cheese appearance, which did not improve with continued ripening. Applying HPP treatment shortly after production (3 d; before the surface flora developed) delayed the development of the cheese rind and the textural ripening of the cheese. This early treatment time also resulted in free whey being expelled from the cheese, creating a firmer body. Applying HPP 11 d after manufacture resulted in >5 log reduction of L. monocytogenes at 450 and 550 MPa with holding times of 10 min. Although HPP was effective at reducing L. monocytogenes associated with bloomy rind cheeses, the quality deterioration would be unacceptable to consumers. Cheesemakers must continue to emphasize sanitation and environmental monitoring to reduce the risk of L. monocytogenes in bloomy rind cheeses.  相似文献   

7.
Reduced-fat cheese showed higher levels of ethanol and lower acetoin than full-fat samples throughout ripening regardless of conditions. Total headspace volatiles, as well as butanoic and hexanoic acids, increased with ripening time and temperature. Full- and reduced-fat cheeses developed distinctly different headspace volatile profiles throughout ripening. The effects of ripening conditions were more notable in full-fat samples. Ripening reduced-fat Cheddar cheese at an elevated temperature for a limited time may enhance development of some desirable volatiles such as butanoic acid.  相似文献   

8.
目的获得加速半硬质山羊奶干酪成熟的非发酵剂乳酸菌菌株(non-starterlacticacidbacteria,NSLAB)。方法以前期分离自地中海地区山羊奶干酪中的2株优良NSLAB菌株为研究对象,测定其对干酪成熟过程中组成成分、微生物菌群、蛋白质水解和质构的影响。结果添加NSLAB菌株对干酪组成成分没有显著影响, NSLAB菌株没有影响乳球菌生长,在干酪成熟期间pH 4.6-SN和12%TCA-SN逐渐增加,且添加NSLAB的干酪在成熟30 d后显著增加了pH 4.6-SN和12%TCA-SN含量, 5%PTASN/TN的增加主要是由于乳酸菌中肽酶作用的结果, SDS-PAGE电泳结果说明添加NSLAB菌株的干酪中小分子多肽含量明显比对照干酪多,RP-HPLC分析得出干酪水溶性中肽的数量随着成熟时间增加。添加NSLAB菌株A-3没有改变干酪的硬度,使干酪的弹性增加。结论添加菌株A-3作为NSLAB的干酪样品中微生物自溶率高,蛋白水解程度强,质构性能良好,具有加速干酪成熟的潜力,是山羊奶干酪工业化生产的优良NSLAB。  相似文献   

9.
We applied capillary electrophoresis, liquid chromatography coupled with tandem mass-spectrometry (MS/MS), and ultra-performance liquid chromatography to determine the composition of water-insoluble and water-soluble proteinaceous fractions of the cheese and to study in detail the degradation of caseins during 8 mo of ripening of Estonian high-temperature cooked hard cheese Old Saare. The application of high-resolution and high-accuracy MS/MS enabled identification of more than 3,000 small peptides, representing a fairly full casein peptidome containing peptides of 4 to 25 AA in length: 1,049 from β-casein (CN), 944 from αS1-CN, 813 from αS2-CN, and 234 from κ-CN. The majority of β-CN- and αS1-CN-derived peptides originated from the N-terminal parts of the molecule, f6-93 and f1-124, respectively; peptides from αS2-CN arose predominantly from the C-terminal end f100-162. At the beginning of ripening, we found a relatively high amount of peptides originating from the glycomacropeptide part of κ-CN, whereas peptides from para-κ-CN prevailed during the later stages of ripening of the cheese. The cleavage patterns of β-CN, αS2-CN, as well as αS1-CN, showed that primary proteolysis was started mainly by plasmin, although a low proteolytic activity of chymosin was also evident. Based on the analysis of cleavage sites, we observed a significant participation of proteolytic enzymes, including amino- and carboxypeptidases, of both mesophilic and thermophilic starter bacteria in further hydrolysis of oligopeptides during the ripening. Several new phosphopeptides were detected in the result of MS/MS data analysis. The profiles of the estimated concentrations of phosphopeptides revealed that those originating from β-CN and αS1-CN accumulated during cheese maturation. In contrast, we did not notice any generation of phosphopeptides from the highly phosphorylated part of αS2-CN, f25-80, presumably due to the inaccessibility of this region to the action of plasmin and chymosin. The analysis of cleavage sites and the combination of principal component and clustering analyses provided a characterization of the complex dynamics of formation and degradation of peptides during cheese maturation. We made an attempt to obtain a comprehensive picture of proteolysis during Old Saare cheese ripening on the basis of the detailed peptidomic data, including also the less abundant peptides determined by MS/MS, and complemented by the data on intact caseins and free AA and reported the results in the paper.  相似文献   

10.
以半硬质契达干酪为研究对象,对同一加工样品在9℃贮存成熟,分别对成熟期0、15、30、45、60、90、120、150、180 d的干酪样品进行了介电特性和成熟度指标的测定,包括干酪样品总氮(total nitrogen,TN)含量、p H 4.6可溶性氮(soluble nitrogen,SN)含量及三氯乙酸(trichloroacetic acid,TCA)溶液中SN含量的测定。测试频率选定为500、915、1 500、2 000 MHz,对测试结果进行了统计分析,建立了干酪介电特性与成熟度指标之间的相关性。结果表明:随着成熟期的延长,干酪水分含量略有减少、水分活度明显降低、p H值先降低后升高、成熟度指数p H 4.6-SN/TN和12%TCA-SN/TN均随成熟期延长而增大;介电常数ε’在所选的测试频率下与成熟期和成熟度指数的变化均呈线性相关关系;介电损耗因数ε’’在所选测试频率范围内,随成熟期的延长和成熟度的增大呈现总体下降趋势,与成熟期和成熟度在500 MHz和915 MHz频率条件下线性相关性极显著(P0.01),而在高频1 500 MHz和2 000 MHz条件下线性相关性不显著;损耗角正切值变化不明显,表明在测试频率范围介电常数ε’和介电损耗因数ε’’的变化方向一致,同时变化幅度相近。  相似文献   

11.
Bifidobacteria cultures were incorporated into Cheddar cheeses to conduct a comparative analysis between the commercially available strain Bifidobacterium animalis ssp. lactis Bb-12 and the wild-type intestinal isolate, Bifidobacterium longum DJO10A. They were incorporated as starter adjuncts in separate vats and as a mixed culture, and survival through manufacturing and cheese ripening was assessed. For cheese using only Bb-12, the cells may have grown during cheese manufacture as 133% of the inoculum was incorporated into the cheese, resulting in 8.00 log cfu/g. Counts remained high during ripening showing less than 1 log decrease over a 12-mo period. For cheese using a mixed culture of Bb-12 and DJO10A, both strains were incorporated at much lower levels: 3.02 and 1.11%, respectively. This resulted in cheese with 6.00 and 5.04 log cfu/g for Bb-12 and DJO10A, respectively. Bifidobacteria survival rates were low, most likely due to the moisture of the cheese being below 38%. The Bb-12 demonstrated almost 100% viability during ripening. Numbers of DJO10A started to decline after 2 mo of ripening and dropped below the level of detection (2 log cfu/g) after 4.5 mo of ripening. Neither DJO10A nor Bb-12 fortified cheeses produced detectable amounts of organic acids during ripening other than lactic acid, indicating the lack of detectable metabolic contribution from bifidobacteria during cheese production and ripening such as production of acetic acid. To determine if sublethal stresses could improve the viability of DJO10A, 2 more vats were made, 1 with DJO10A exposed to sublethal acid, cold, and centrifugation stresses, and 1 exposed to none of these stresses. Although stress-primed DJO10A survived cheese manufacture better, as 72.8% were incorporated into the cheese compared with 41.1% of the unprimed, the statistical significance of this difference is unknown. In addition, the difference in moisture levels in the cheese cannot be excluded as influencing this difference. However, the rate of decline during ripening was similar for both. After 6 mo of ripening, cell counts in cheese were 4.68 and 4.24 log cfu/g for primed and unprimed cultures, respectively. These results suggest that whereas priming bifidobacteria with sublethal stresses before incorporation in a cheese fermentation may improve the number of viable cells that get incorporated into the cheese, it does not affect viability during cheese ripening.  相似文献   

12.
王泽  张岩  陈炼红 《食品科学》2023,44(2):116-124
为研究Edam牦牛半硬质干酪成熟机理,分别测定成熟0、20、40、60、80 d Edam牦牛干酪的感官、理化、物性、蛋白质和脂肪分解指标,采用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳和傅里叶变换红外光谱等方法研究酪蛋白降解情况,通过Pearson相关性分析成熟时间与各指标间的相关性。结果表明:随着成熟时间延长,感官评分先下降后上升;水分含量、pH值下降;亮度值(L*)下降,红度值(a*)和黄度值(b*)值上升;硬度、弹性、胶黏性均上升,凝聚性逐渐下降;储能模量和损耗模量升高,损耗角正切值始终小于1;成熟时间与总氮含量、pH 4.6和12%三氯乙酸条件下干酪中可溶性氮含量等呈极显著正相关(P<0.01);脂肪含量先升高后降低,游离脂肪酸含量和硫代巴比妥酸值逐渐增加。酪蛋白(casein,CN)降解研究结果表明:αs1-CN、αs2-CN、β-CN及κ-CN均随成熟时间延长而不断降解,成熟80 d时大分子蛋白降解明显;成熟过程中β-折叠、α-螺旋逐渐向无规卷曲转化;成熟时间与羰基含量、表面疏水性呈极显著正相关(P<0.01),与总巯基含量呈显著负相关(P<0.05)。  相似文献   

13.
干酪成熟过程发酵剂的作用及快速成熟的研究进展   总被引:1,自引:0,他引:1  
干酪的成熟过程,是在添加酶及各种微生物的协同作用下完成的.干酪中的微生物作用也包括人为添加发酵剂的作用.本文综述了干酪生产过程中发酵剂的使用和成熟过程所起的作用,主要有酸化、改善质构、形成风味物质.此外,本文也讨论了干酪的成熟机制,综述了目前用于促进干酪成熟所使用的一些方法和技术以及对它们的最新研究进展.  相似文献   

14.
The fate of 2 different Listeria innocua strains was analyzed during the production and ripening of smeared raw milk Greyerzer cheese (Gruyère). These strains were used as surrogates for the pathogenic Listeria monocytogenes, as they are physiologically very similar. Bacterial cells were added to the cheese milk at levels of 105 cfu/mL. During the first 24 h of cheese making, the number of the test strains decreased to a level of below 102 cfu/g. Obviously, the cooking temperature of 56°C and the subsequent slight temperature decrease to 50°C within 70 min contributed to a distinct reduction of Listeria counts. The counts in the cheese cores did not exceed 103 cfu/g within 12 wk of cheese ripening and Listeria was not detectable after 24 wk. In contrast to the cores of the cheeses of the 4 batches in this study, their rinds always contained a high listerial load of approximately 106 to 108 cfu/g throughout the entire ripening period. The smeared surface showed an increase of pH to alkaline values, corresponding to smear microbiota development. Coryneforms and Staphylococcus counts were stable at >107 cfu/cm2 over 175 d, whereas yeast counts decreased to about 105 cfu/cm2 at the end of ripening. The study shows that the smear culture had no noticeable anti-listerial potential. When removing the rind or portioning such smeared cheese loaves with a cutting device, a postprocess contamination of the core might occur, thus presenting a major hygienic risk.  相似文献   

15.
The changes in composition and some biochemical properties of Örgü cheeses made from raw (RMC) and pasteurized (PMC) cow milk were investigated during a 90-day ripening period. The average contents of total solids (TS), protein, water soluble nitrogen (WSN), trichloro-acetic acid soluble nitrogen (TCA-SN) and acid degree value (ADV) were lower, while salt and salt in TS were found to be statistically higher in PMC than RMC (P < 0.05). In addition, in both RMC and PMC, the TS and protein contents were decreased as compared to an increase in salt, salt in TS, WSN and TCA-SN contents, and ADV, during ripening (P < 0.05). The evaluation of WSN, TCA-SN and ADV shows that these two experimental Örgü cheese types undergo little proteolysis and lipolysis. On the other hand, acidity development was observed to be high in both before curdling and in cheese made from raw milk during ripening.  相似文献   

16.
Wang F  Zhang X  Luo J  Guo H  Zeng SS  Ren F 《Journal of food science》2011,76(3):E248-E253
The changes in proteolysis, calcium (Ca) equilibrium, and functional properties of natural Cheddar cheeses during ripening and the resultant processed cheeses were investigated. For natural Cheddar cheeses, the majority of the changes in pH 4.6 soluble nitrogen as a percentage of total nitrogen (pH 4.6 SN/TN) and the soluble Ca content occurred in the first 90 d of ripening, and subsequently, the changes were slight. During ripening, functional properties of natural Cheddar cheeses changed, that is, hardness decreased, meltability was improved, storage modulus at 70 °C (G'T=70) decreased, and the maximum tan delta (TDmax) increased. Both pH 4.6 SN/TN and the soluble Ca were correlated with changes in functional properties of natural Cheddar cheeses during ripening. Kendall's partial correlation analysis indicated that pH 4.6 SN/TN was more significantly correlated with changes in hardness and TDmax. For processed cheeses manufactured from natural Cheddar cheeses with different ripening times, the soluble Ca content did not show significant difference, and the trends of changes in hardness, meltability, G'T=70, and TDmax were similar to those of natural Cheddar cheeses. Kendall's partial correlation analysis suggested that only pH 4.6 SN/TN was significantly correlated with the changes in functional properties of processed cheeses.  相似文献   

17.
The volatile composition and sensory properties of industrially produced Idiazabal cheeses made from ewes’ raw milk (RM) or pasteurised milk (PM) and with addition of different starter cultures were compared. Cheeses were analysed at 90 and 180 d of ripening. Acids were the major volatile compounds in RM cheeses. Methyl ketones were the major volatile compounds in PM cheeses at 90 ripening days. However, the content of acids strongly increased with ripening whereas the content of ketones decreased in PM cheeses. The concentration of esters was higher in RM cheeses than in PM cheeses. No differences were found in the content of alcohols. Most aldehydes, hydrocarbons, terpenes and furans identified were minor volatile compounds in both RM and PM cheeses. In RM cheeses, characteristic sensory attributes for the aroma of Idiazabal cheese were present at 3 months, whereas in PM cheeses those desirable sensory attributes did not appear until 6 months of ripening.  相似文献   

18.
Four different types of mould‐ripened Civil cheese were manufactured. A defined (nontoxigenic) strain of a Penicillium roqueforti (SC 509) was used as the secondary starter with and without addition of the whey cheese (Lor); in parallel, secondary starter‐free counterparts were manufactured. Chemical composition, microbiology and proteolysis were studied during the ripening. The incorporation of whey cheese in the manufacture of mould‐ripened Civil cheese altered the gross composition and adversely affected proteolysis in the cheeses. The inoculated P. roqueforti moulds appeared to grow slowly on those cheeses, and little proteolysis was evident in all cheese treatments during the first 90 days of ripening. However, sharp increases in the soluble nitrogen fractions were observed in all cheeses after 90 days. Microbiological analysis showed that the microbial counts in the cheeses were at high levels at the beginning of ripening, while their counts decreased approximately 1–2 log cfu/g towards the end of ripening.  相似文献   

19.
ABSTRACT: Free amino acid profiles of Port Salut Argentino cheeses at different storage conditions (ripening with and without previous frozen storage), ripening times (1, 6, 13, 27, and 56 d), and cheese zones (central and external) were studied. Derivatization with o-phtaldialdehyde and a C18 column were used for chromatographic separations. Principal component analysis reduced data to 2 dimensions where unripened cheeses (1 to 13 d) were grouped independently of ripening time, sampling zone, and storage condition. Ripened cheeses (27 and 56 d) showed scattering according to ripening time. The contribution of free amino acid profiles to quality in cheeses preserved by frozen storage may be considered similar to that in traditionally ripened cheeses.  相似文献   

20.
The simultaneous effects of processing variables such as ripening time (20–60 days), ripening temperature (6–10 °C), level of rennet added (1–2 g/100 kg milk) and brine concentration (8–14%, w/v) on the proteolysis, lipolysis and sensory score of Iranian white brined cheese (Feta type) were explored by the means of response surface methodology. The most important effect in proteolytical terms was produced by ripening temperature and ripening time in linear form, but level of rennet added and brine concentration were also significant at the 5% level. In terms of lipolysis, ripening time was dominant factor in both linear and quadratic forms; quadratic effect of ripening temperature was greater than its linear effect.  相似文献   

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