High Hydrostatic Pressure for Accelerating Ripening of Goat's Milk Cheese: Proteolysis and Texture

High hydrostatic pressurization is proposed for cheese ripening acceleration. Several treatments were used for accelerating ripening of goat's milk cheese: 50 MPa / 72 h, 400 MPa / 5 min and 400 MPa / 5 min followed by 50 MPa / 72 h all at 14 °C. Moisture content and pH were higher in 400 MPa treatments compared to the others. By measuring proteolysis indexes, 400 MPa treatments were found to accelerate ripening (14 d in contrast to 28 d conventionally) due to enhanced enzyme activity from inoculated starter culture. Sensory analysis indicated bitter notes in the accelerated ripened cheese. Pressurized cheeses were less crumbly and more elastic than control.     

解淀粉芽孢杆菌GSBa-1凝乳酶对羊奶干酪成熟特性的影响

为探究解淀粉芽孢杆菌GSBa-1凝乳酶制备的羊奶干酪(干酪B)成熟特性的变化,以采用商业凝乳酶和同批次羊奶制作的干酪(干酪A)为对照组,比较两组干酪在60d成熟期主要组分、质构特性、微生物指标及风味物质的变化。结果表明,两组干酪得率相差不大。成熟期间干酪的水分、蛋白质及脂肪含量呈先上升后下降趋势,干酪B始终高于干酪A;干酪游离氨基酸总量在成熟期间呈先下降后上升趋势,且干酪B中苯丙氨酸、天冬氨酸、异亮氨酸、甲硫氨酸、丝氨酸含量高于干酪A。成熟前期干酪B质构特性优于干酪A。干酪A成熟后乳酸乳球菌数量增加了(5.22±0.02)%,干酪B无显著变化(P>0.05)。成熟期内,两组干酪中挥发性风味物质种类和含量均增加,但干酪B中的壬酸、辛醇、2-庚酮、2-壬酮、二甲基砜使羊奶干酪风味独特、浓郁。因此,GSBa-1凝乳酶具备替代商业凝乳酶用于羊奶干酪生产的潜力,可对干酪风味的形成和品质的提升起到一定促进作用。     

SDS-PAGE of Proteins in Goat Milk Cheeses Ripened under Different Conditions

Proteolytic characteristics of five varieties of commercial goat milk cheeses and a cow milk Cheddar aged under different conditions were evaluated by SDS-PAGE and an advanced densitometry system. All fresh goat cheeses had distinctively lower intensities of α_S1-casein (CN) bands than those of cow milk Cheddar, whereas intensities of β-CN were much greater in the goat cheeses. The PAGE patterns clearly displayed α_S2-CN in all goat cheese, but it was negligible in cow milk Cheddar. The greater protein degradation in hard goat cheeses than cow milk Cheddar at 4°C and 22°C strongly correlated with water-soluble nitrogen compound concentrations and densitometric values of corresponding cheeses.     

成熟温度和时间对Cheddar干酪成熟特性的影响研究

通过对不同成熟参数下Cheddar干酪蛋白分解、质构、pH及感官评价的分析,探讨了成熟参数对Cheddar干酪的影响,并得出研究条件下的最优成熟温度和时间,分析了Cheddar干酪在成熟过程中的游离氨基酸变化情况。     

Monitoring Proteolysis During Cheddar Cheese Ripening Using Two-Dimensional Gel Electrophoresis

A 2-D gel electrophoretic method, consisting of isoelectric focusing and alkaline urea-PAGE was used to monitor proteolysis during ripening (180d, 5°C and 8°C) of full- and reduced-fat Cheddar cheese. The method enabled quantifying changes in levels of peptides in cheese with good spot-resolution. Results can complement those from other analyses, especially those for determining low MW peptides. Notable effects were found for cheese composition and ripening temperature on gel pattern and on relative levels of selected proteolysis products. In both cheese varieties, most peptides reached a maximum during the first 3 ripening months and gradually disappeared as ripening advanced.     

Milk Plasmin Activity Influence on Cheddar Cheese Quality during Ripening

Up to six-fold increase in plasmin activity in milk did not significantly (p<0.05) affect the composition (moisture, protein, NaCl) of cheese, although a slight increase in moisture and decrease in protein content of the cheese was noted. Proteolysis in cheese increased with plasmin activity, resulting in improved flavor and overall quality of the cheese after 3 and 6 months ripening. Consistently, increasing the plasmin activity in milk about three-fold resulted in cheese of superior sensory quality.     

High Pressure Treatment of Milk and Effects on Microbiological and Sensory Quality of Cheddar Cheese

The effect of cycled high pressure treatment of milk on the yield, sensory, and microbiological quality of Cheddar cheese was investigated. Cheddar cheeses were made from pasteurized, raw, or pressure treated milk according to traditional methods. Flavor scores from trained dairy judges were not different for pasteurized and pressurized milk cheeses (P≤0.05). Percent moisture and wet weight yields of pressure treated milk cheeses were higher than pasteurized or raw milk cheeses (P≤0.05). Microbiological quality of pressurized milk cheeses was comparable to pasteurized milk cheeses. Texture defects were present in pressurized milk cheeses and were attributed to excess moisture. High pressure treatment of milk shows promise as an alternative to heat pasteurization prior to cheesemaking.     

Kinetics of Casein Degradation during Ripening of Fynbo Cheese Salted with NaCl/KCl Brine

First-order kinetics with respect to the α_s1-casein concentration was used to study casein degradation during low-fat Fynbo cheese ripening. Effects of partial NaCl replacement by KCI during cheese salting were studied by statistical treatment of the casein degradation results. Four zones from cheeses at 1, 5, 10, 20, and 30 ripening days were analyzed by a polyacrylamide gel electrophoresis method. Similar kinetic parameters were obtained for a cheese salted with a NaCl/KCl brine and for a control cheese during ripening. Results were more affected by salt concentration than by salt substitution. KCl did not strongly influence kinetics of Fynbo cheese proteolysis.     

响应曲面法优化羊乳牛乳混合干酪出品率

采用响应曲面法建立了半硬质羊乳牛乳混合干酪出品率的二次多项数学模型,验证了模型的有效性,并考察凝乳酶添加量、酸化值和CaCl2添加量对混合干酪出品率的影响,优化出混合干酪出品率的工艺参数为凝乳酶添加量3747.25SU,酸化值5.99,CaCl2添加量0.04%,并且干酪的品质较好。     

Free Amino Acid Profiles During Ripening of Port Salut Argentino Cheese After Frozen Storage

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.     

蓝纹牦牛干酪成熟特性及其风味分析

牦牛乳具有高蛋白、高脂肪的营养特性以及较好的抗疲劳等功能特性。然而,由于牦牛乳产量较低,且产地分散,其在干酪产品开发等精深加工方面研究较少。采用娄地青霉为次级发酵剂,开发蓝纹牦牛干酪,并对其成熟特性以及风味物质进行分析。研究结果显示,娄地青霉能够在牦牛干酪中迅速生长,促进蛋白质的降解并形成大量的多肽、氨基酸等。牦牛干酪成熟末期游离氨基酸,尤其是鲜味氨基酸含量显著升高(P＜0.05)。利用SPME-GC/MS技术在牦牛干酪中共检测出53种风味物质。正交偏最小二乘分析(OPLS-DA)分析显示,与成熟初期相比,蓝纹牦牛干酪风味物质构成在成熟未期发生显著变化,挥发物总含量显著增加(P＜0.05)。牦牛干酪中酯类风味物质主要以脂肪甲酯类为主,且在成熟后期(25、46d)含量相对稳定;脂肪酸类化合物含量在成熟中期最高,但是在成熟末期显著降低(P＜0.05);酮类化合物尤其是甲基酮类,在成熟后期含量显著增加(P＜0.05)。2-壬酮、2-庚酮、辛酸甲酯、2-戊酮、癸酸乙酯、癸酸甲酯、己酸、2-辛酮、丁酸等风味化合物是蓝纹牦牛干酪的主要风味物质。研究表明,娄地青霉能够良好地促进牦牛干酪的成熟,且对牦牛干酪的营养特性以及特征风味的形成具有显著影响。研究结果旨在为我国牦牛乳等特色乳品的深加工奠定理论基础,同时为我国特色乳品产业发展提供参考。     

Ripening Profile of Semi-Hard Standard Goat Cheese Made From Pasteurized Milk

The microbial groups, physico-chemical characteristics, proteolysis, lipolysis, and rheological properties over a 30-day ripening period of a semi-hard cheese from pasteurized goat's milk were investigated. The count of aerobic mesophilic flora was high in cheese throughout ripening with lactic acid bacteria being the main microbial group. Halophilic bacteria, yeast and molds showed initial low counts but maintained their levels relatively constant during the ripening period. The main biochemical modification of cheese during ripening was related to the extent of proteolysis. The water soluble nitrogen in the semi-hard cheese increased during ripening. Lipolysis also occurred throughout the ripening period, with the major constituents being the palmitic, oleic, myristic, capric, and lauric acids. The rheological study suggested that the most important factors influencing the texture of the goat cheese is the level of total solids, and the extent of protein degradation recorded as soluble nitrogen during the ripening period. Rheological properties of goat cheese showed a transformation from a soft and elastic consistency to a hard and brittle body as a function of aging.     

豆奶干酪成熟过程中蛋白水解的研究

本文主要研究了豆奶干酪成熟过程中蛋白水解的变化,并与纯牛乳干酪进行比较。结果表明:豆奶干酪中pH4.6 SN 和12%TCA SN随着时间的延长逐渐增高,而且pH4.6 SN的增长速度比12%TCA SN快,这与纯牛乳干酪是一致的,但豆奶干酪的可溶性氮低于同一时期的纯牛乳干酪。     

Probiotic Cheddar Cheese: Influence of Ripening Temperatures on Proteolysis and Sensory Characteristics of Cheddar Cheeses

ABSTRACT:  Bifidobacterium longum 1941, B. animalis subsp. lactis LAFTI^® B94, Lactobacillus casei 279, Lb. casei LAFTI L26, Lb. acidophilus 4962, or Lb. acidophilus LAFTI L10 were used as an adjunct in the production of Cheddar cheeses, which were ripened at 4 and 8 °C for 24 wk. Effects of ripening temperatures and probiotic adjuncts on proteolysis and sensory evaluation of the cheeses were examined. Higher ripening temperature increased the level of proteolysis in the cheeses. Product of proteolysis and organic acids released during ripening were shown to be important for the flavor of Cheddar cheeses. There were positive and significant correlations between the levels of soluble nitrogen, lactic, acetic, and butyric acids, percentage hydrolysis of α_s1-CN and β-CN to the scores of cheddary flavor ( P < 0.05). Scores for sour-acid and vinegary flavors were higher in cheeses with the addition of Bifidobacterium sp. or Lb. casei 279 ripened at 8 °C. The scores were positively and significantly correlated to the level of lactic, acetic, and free amino acids in the cheeses ( P < 0.05). The results show that both 4 and 8 °C have potential for use in the ripening of probiotic Cheddar cheeses.     

Cheddar Cheese Ripening and Flavor Characterization: A Review

Cheddar cheese is a biochemically dynamic product that undergoes significant changes during ripening. Freshly made curds of various cheese varieties have bland and largely similar flavors and aroma and, during ripening, flavoring compounds are produced that are characteristic of each variety. The biochemical changes occurring during ripening are grouped into primary events including glycolysis, lipolysis, and proteolysis followed by secondary biochemical changes such as metabolism of fatty acids and amino acids which are important for the production of secondary metabolites, including a number of compounds necessary for flavor development. A key feature of cheese manufacture is the metabolism of lactose to lactate by selected cultures of lactic acid bacteria. The rate and extent of acidification influence the initial texture of the curd by controlling the rate of demineralization. The degree of lipolysis in cheese depends on the variety of cheese and may vary from slight to extensive; however, proteolysis is the most complex of the primary events during cheese ripening, especially in Cheddar-type cheese.     

不同菌种大豆干酪后熟过程的研究

研究了3种不同大豆干酪后熟过程的变化情况。结果表明,L.rhamnosus+S.carnosus大豆干酪具有最低的pH和最高的酸度,同时具有最高的氨基氮含量和最高的活菌数。游离氨基酸分析表明,L.rhamnosus+S.carnosus大豆干酪中的游离氨基酸总量最高;L.rhamnosus大豆干酪降解产生的游离氨基酸以谷氨酸和精氨酸为主,S.carnosus大豆干酪和L.rhamnosus+S.carnosus大豆干酪降解产生的游离氨基酸则以色氨酸为主。脂肪酸分析表明,L.rhamnosus+S.carnosus大豆干酪C20以上的长链脂肪酸得到更加充分的降解。     

添加超滤牛乳的拉斯干酪特性

拉斯干酪添加有超滤牛乳制得,该牛乳中乳固形物质量分数分别为对照样(纯牛乳)的1.4、1.6和2.0倍,成熟3个月.拉斯干酪显示了比对照样更高的干酪得率,其水分、脂肪质量分数和pH值与对照样的相似,在成熟期均呈下降趋势,但氮质量分数等均呈上升趋势,且以牛乳中乳固形物质量分数提高到对照样的1.6倍时最高.结果表明,乳固形物质量分数为对照样1.6倍时牛乳制得的拉斯干酪其感官特性最佳.     

成熟温度对牦牛毛霉菌奶酪成熟过程中品质的影响

文章通过研究不同成熟温度对牦牛毛霉菌奶酪成熟过程的影响,找寻最适应的温度及成熟时间.选取实验材料牦牛毛霉菌奶酪,将其置于不同的成熟温度下(20,25,30℃),选取相应成熟时间节点,测定质构、色泽、蛋白质分解、pH值等.结果 表明,成熟温度为25℃时,牦牛毛霉菌奶酪在第6天时质构达到最佳值,此时感官评分也较高.3组牦牛...     

Accelerated Cheddar Cheese Ripening with an Aminopeptidase Fraction from Squid Hepatopancreas

ABSTRACT: An aminopeptidase (AP) fraction from squid (Illex illecebrosus) hepatopancreas was added to Cheddar cheese at 2 levels, and its influence on ripening indices was determined for up to 3-mo storage at 11 °C. Two commercial enzymes (Neutrase ® and Flavourzyme ®) were similarly tested. Cheese with the higher level of squid AP contained more soluble N, amino acids, and Cheddar flavor after 1 mo, but it developed defects in texture and bitterness as ripening progressed. Cheese with less squid AP did not differ from the control with respect to all ripening indices over 3-mo storage. Ripening Cheddar contains cysteine protease inhibitor(s) that inhibit low levels of squid AP but not Neutrase ® and Flavourzyme ®.     

Reverse-Phase HPLC Analysis of Reference Cheddar Cheese Samples for Assessing Accelerated Cheese Ripening

Applying water extracts from Cheddar cheese to an octadecyl vinyl alcohol copolymer column using a reliable auto-sampling system provided highly repeatable HPLC patterns. Two batches of standard samples of mild, medium, sharp, and extra-sharp and one batch of abused samples (rapidly aged under abnormal conditions) were analyzed. Principal component similarity (PCS) analysis indicated similar shifts of plots due to aging of the standard batches, while the plot for the abused batch deviated from the pathway of normal aging. PCS may be useful for analysis of accelerated ripening effects as well as finding unusual samples during quality control.