地衣芽孢杆菌凝乳酶对切达干酪成熟过程中蛋白水解的影响

利用地衣芽孢杆菌凝乳酶制作切达干酪和切达干酪类似物,分析干酪成熟过程中各蛋白水解指标的变化规律,以揭示地衣芽孢杆菌凝乳酶对切达干酪成熟过程中蛋白水解的影响。结果表明,CDF组（添加地衣芽孢杆菌D3.11凝乳酶所制切达干酪）、CD3组（添加地衣芽孢杆菌D3.11凝乳酶但未添加发酵剂制成的干酪类似物）和CCF组（添加商品凝乳酶所制切达干酪）干酪蛋白含量、pH 4.6-可溶性氮、12%三氯乙酸-可溶性氮、5%磷钨酸-可溶性氮、总游离氨基酸含量均随着成熟时间延长呈显著增加趋势,并且成熟期间CDF组干酪均显著高于CCF组干酪（P＜0.05）;十二烷基硫酸钠-聚丙烯酰氨凝胶电泳分析表明,CDF组干酪α-酪蛋白水解程度较大;pH 4.6-可溶性肽段分析表明,随着干酪的成熟,总肽含量呈先增加后下降趋势,但疏水性肽与亲水性肽的比值呈持续下降趋势,在成熟第6个月时,CDF组、CD3组和CCF组干酪疏水性肽与亲水性肽比值分别为2.668、2.822、3.788。主成分分析表明,3 组干酪的蛋白水解程度与成熟度呈正相关,与疏水性肽和亲水性肽的比值呈负相关。以上结果表明,利用地衣芽孢杆菌凝乳酶制作的干酪蛋白水解度更高,但其疏水性肽比例较小,研究结果可为地衣芽孢杆菌凝乳酶在干酪生产中的应用提供理论依据。     

发酵剂添加量和成熟时间对牦牛乳硬质干酪脂肪氧化的影响

为研究发酵剂添加量和成熟时间对牦牛乳硬质干酪中脂肪氧化的影响,试验以添加不同发酵剂质量分数(1%、2%、3%)制得的牦牛乳硬质干酪为材料,对其90 d成熟期内的氧化指标和理化指标进行测定。结果表明:发酵剂添加量和成熟时间对牦牛乳硬质干酪的理化指标和脂肪氧化程度均有显著性影响(P <0. 05),且随发酵剂添加量的增加,干酪中酸度值(acidity value,ADV)、过氧化值(peroxide value,POV)、羰基价(carbonyl value,CV)、硫代巴比妥酸值(thiobarbituric acid value,TBA)增加;随成熟时间的延长,ADV、CV、TBA值增加,POV值先增加后降低。发酵剂添加量为3%时,能够显著增大干酪中脂肪的氧化程度(P <0. 05),同时随成熟时间的延长,脂肪氧化持续进行并且氧化程度也在不断加深。该研究将发酵剂添加量和成熟时间相结合,探讨牦牛乳硬质干酪中脂肪氧化的变化规律,以期从脂肪的氧化机制调控干酪的品质,为实现工业化生产提供理论依据。     

高熔点再制干酪的初探

研究了再制干酪基础配方中,原制干酪成熟度、水分添加量、脂肪添加量、乳化盐种类及添加量对熔点的影响,在单因素实验基础上,采用二次回归正交旋转组合的实验设计,得到的最优配方:采用6个月成熟的切达干酪,水分添加9.5%(w/w),乳化盐2%(w/w),黄油0%(w/w),该配方比普通再制干酪熔点提高30℃以上。     

水分和盐分对Cheddar干酪介电特性的影响

利用同轴探头技术,研究室温(22℃)下10~3000 MHz频段内不同水分质量分数(25.76%~36.94%)和不同盐的添加量(0~3%)对干酪(成熟30 d)介电特性的影响。结果表明,干酪的相对介电常数和介电损耗因子随水分质量分数的增加而增大。相对介电常数因加盐明显减小,而介电损耗因子随盐分质量分数的增加线性增加。在特定频率200、915、2450 MHz下水分和相对介电常数相关性极显著,与介电损耗因子相关性显著。在添加盐的干酪中,盐的添加量和介电损耗因子相关性极显著,盐分质量分数对介电损耗因子影响极显著。     

高熔点再制干酪的初探

研究了再制干酪基础配方中,原制干酪成熟度、水分添加量、脂肪添加量、乳化盐种类及添加量对熔点的影响,在单因素实验基础上,采用二次回归正交旋转组合的实验设计,得到的最优配方:采用6个月成熟的切达干酪,水分添加9.5%(w/w),乳化盐2%(w/w),黄油0%(w/w),该配方比普通再制干酪熔点提高30℃以上。      

干酪介电特性与成熟期及成熟度相关性分析

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。     

瑞士乳杆菌对契达干酪成熟期间品质的影响

干酪的成熟是形成干酪特有的组织状态、质地和风味的关键工序。将分离自内蒙古传统乳制品中的瑞士乳杆菌SMN2-1作为非发酵性乳酸菌添加到契达干酪的生产中,通过检测其成熟过程中理化指标、气味变化和质构特性等指标,分析了瑞士乳杆菌对契达干酪成熟的影响。结果显示:在90 d的成熟期内,两组干酪的蛋白质、脂肪、水分和盐分含量之间差异不显著(p>0.05),但添加瑞士乳杆菌SMN2-1的干酪成熟第90 d的气味明显改变,内聚性、弹性和咀嚼性等物性指标均高于对照,因此添加瑞士乳杆菌SMN2-1可以有效促进蛋白质分解和干酪的成熟,同时改善干酪的风味和质地。     

菊粉对切达干酪品质的影响

菊粉是一种天然的脂肪替代物,且具有一定的益生作用。通过向标准化后的原料乳中添加不同质量比(w/w)的菊粉,研究菊粉对切达干酪理化特性、活菌数量、质构和感官评定的影响。结果表明,9%菊粉能够显著地提高切达干酪的水分含量(p0.05),并能够改善切达干酪的质构特性,从而得到低脂肪含量的软质切达干酪。研究结果为新型切达干酪的开发提供了新思路。     

KCl部分替代NaCl制作低盐切达干酪的研究

为减少切达干酪中钠含量,研究KCl部分替代NaCl对切达干酪组成成分,矿物质Na、K含量,乳酸菌总数,质构和苦味等方面的影响。切达干酪利用5种不同的盐处理方式制作,分别是(A)1.7%NaCl,(B)0.85%NaCl,(C)3NaCl:1KCl,(D)1NaCl:1KCl和(E)1NaCl:3KCl。研究表明,KCl部分替代NaCl对干酪中蛋白质,脂肪和水分含量无显著影响(P0.05),钠含量显著降低(P0.05),钾含量显著升高(P0.05),对乳酸菌总数,p H值,硬度影响较小,在干酪成熟28 d时,50%KCl替代对干酪弹性无显著性影响(P0.05)。在苦味评分方面,KCl替代25%和50%NaCl的干酪与正常盐干酪差异不显著(P0.05)。以苦味评定值为主指标,结合其它性能指标,确定KCl∶NaCl为1∶1时,既不影响切达干酪的风味,又可以最大程度的降低干酪中的钠含量。KCl部分替代NaCl可以弥补低盐干酪(0.85%NaCl)水分含量高,p H值低,结构松散,硬度下降,苦味严重等缺陷。     

以大豆为主要原料制备新鲜豆乳干酪的工艺研究

豆乳干酪,是以豆乳取代牛乳的一种类似干酪的新型发酵豆制品。以大豆为主要原料,添加牛乳,采用牛乳干酪发酵剂发酵制备新鲜豆乳干酪,并对制备豆乳干酪的关键工艺参数进行研究,探讨发酵剂添加量对新鲜豆乳干酪在储藏14 d内的理化指标和质构特性的影响。结果表明,发酵剂添加量的不同对大豆干酪理化特性存在显著差异(p0.05)。随储藏时间的增加,豆乳干酪水分逐渐降低,pH缓慢下降,在相同接菌量条件下,不同储藏期内大豆干酪的硬度、弹性、咀嚼性逐渐降低。在接菌量不同时,豆乳干酪质构数值差异显著。试验结果显示,添加0.03%的发酵剂有利于新鲜豆乳干酪的制备。     

EFFECT OF CALCIUM AND PHOSPHORUS, RESIDUAL LACTOSE AND SALT-TO-MOISTURE RATIO ON TEXTURAL PROPERTIES OF CHEDDAR CHEESE DURING RIPENING

The texture profile analysis (TPA) parameters and meltability of Cheddar cheeses with varying levels of calcium (Ca) and phosphorus (P) content, residual lactose content and salt‐to‐moisture (S/M) ratio were studied at 0, 1, 2, 4, 6 and 8 months of ripening. The TPA hardness had an inverse relationship with the meltability of Cheddar cheese and at any given ripening time, lower TPA hardness corresponded to higher meltability of Cheddar cheese. Higher Ca and P content (0.67% Ca and 0.53% P) in Cheddar cheese resulted in up to 22.8, 5.7, 14.6, 13.5 and 35.2% increase in hardness, springiness, cohesiveness, resilience and chewiness values, respectively, and up to 23.5 and 27.7% decrease in meltability and adhesiveness values during ripening compared to the Cheddar cheese prepared with lower Ca and P content (0.53% Ca and 0.39% P). Higher residual lactose content (1.4%) in Cheddar cheese resulted in up to 24.6, 8.8 and 20.0% increase in hardness, cohesiveness and chewiness values, respectively, and up to 12.7% decrease in meltability value in the Cheddar cheese during ripening compared to the lower lactose content (0.78%). High S/M ratio (6.4) resulted in up to 29.4, 30.3 and 29.4% increase in hardness, adhesiveness and chewiness values, respectively, and up to 7.3% decrease in meltability value in Cheddar cheese compared to low S/M ratio (4.8) during ripening.     

双蛋白切达干酪成熟过程中的质构和感官评价分析

在原料乳中添加质量分数为10%豆乳进行切达干酪加工,研究成熟过程中豆蛋白和筛选发酵剂对干酪质构及感官影响。结果表明,豆乳和发酵剂对干酪的基础理化指标有显著影响,从干酪质构分析结果可以看出,干酪在成熟期间,豆乳的添加对干酪的硬度、弹性、黏聚性和咀嚼性都有显著影响,干酪硬度和咀嚼度下降。应用发酵剂L.Lactis subsp.Cremoris QH27-1和L.Lactis subsp.LactisXZ3303生产双蛋白切达干酪可以提高干酪的质构特征和感官品质。     

Application of exopolysaccharide-producing cultures in reduced-fat Cheddar cheese: texture and melting properties

Textural, melting, and sensory characteristics of reduced-fat Cheddar cheeses made with exopolysaccharide (EPS)-producing and nonproducing cultures were monitored during ripening. Hardness, gumminess, springiness, and chewiness significantly increased in the cheeses as fat content decreased. Cheese made with EPS-producing cultures was the least affected by fat reduction. No differences in hardness, springiness, and chewiness were found between young reduced fat cheese made with a ropy Lactococcus lactis ssp. cremoris [JFR1; the culture that produced reduced-fat cheese with moisture in the nonfat substance (MNFS) similar to that in its full-fat counterpart] and its full-fat counterpart. Whereas hardness of full-fat cheese and reduced-fat cheese made with JFR1 increased during ripening, a significant decrease in its value was observed in all other cheeses. After 6 mo of ripening, reduced fat cheeses made with all EPS-producing cultures maintained lower values of all texture profile analysis parameters than did those made with no EPS. Fat reduction decreased cheese meltability. However, no differences in meltability were found between the young full-fat cheese and the reduced-fat cheese made with the ropy culture JFR1. Both the aged full- and reduced-fat cheeses made with JFR1 had similar melting patterns. When heated, they both became soft and creamy without losing shape, whereas reduced-fat cheese made with no EPS ran and separated into greasy solids and liquid. No differences were detected by panelists between the textures of the full-fat cheese and reduced-fat cheese made with JFR1, both of which were less rubbery or firm, curdy, and crumbly than all other reduced-fat cheeses.     

Physicochemical properties of low-fat and full-fat Cheddar cheeses

Low-fat (6% fat) and full-fat (32% fat) Cheddar cheese was manufactured and aged up to 6–9 months at 5°C. The objective was to study the impact of fat on the physicochemical properties of Cheddar cheese. Total soluble nitrogen (TSN) and protein nitrogen (TPSN) in aqueous extracts were determined by the Kjeldahl method. The peptide content of each cheese was determined with reverse phase chromatography (RPC). Low-fat Cheddar (LFC) had a markedly higher peptide content than full-fat Cheddar (FFC). The overall peptide quantity increased with age with a marked increase in hydrophobic peptide content. Rheological properties were determined using an Instron Universal Testing Machine. LFC had significantly higher stress values, indicating hard and rubbery texture, than FFC. Furthermore, LFC had lower strain values, indicating crumbliness.     

快速成熟契达干酪成熟期间的理化特性变化

对天然契达(Cheddar)干酪快速成熟期间理化特性进行了研究,结果表明,在21 d内,pH值呈下降趋势(P<0.05),在21 d到35 d的成熟中,pH值缓慢增加(P>0.05);Cheddar干酪快速成熟过程中由于蛋白酶和脂肪酶的作用使蛋白发生水解,pH值为4.6醋酸溶液—水溶性氮质量分数、质量分数为12%的三氯乙酸—可溶性氮和游离氨基酸(FAA)的质量分数都呈明显增加趋势(P<0.05);成熟过程中TPA各项指标均有不同程度的变化,硬度和凝聚性呈先下降后增加的趋势,弹性和咀嚼性呈先上升后下降的趋势。     

The accelerated ripening of cholesterol-reduced Cheddar cheese by crosslinked β-cyclodextrin

This study was carried out to investigate the influence of salt content on cholesterol-reduced Cheddar cheese obtained by a treatment with crosslinked β-cyclodextrin (β-CD) and to find if the ripening process was accelerated in cholesterol-reduced cheese. The crosslinked β-CD used was made by adipic acid. A primary study indicated that the chemical and rheological properties were not changed by the salt addition and the composition of Cheddar cheese treated with crosslinked β-CD was similar to untreated Cheddar cheese. Approximately 91 to 92% cholesterol reduction was observed in the cheeses that were treated using β-CD. In a subsequent study, we found accelerated ripening by the crosslinked β-CD based on the productions of short-chain free fatty acids and free amino acids. In rheological properties, elasticity, cohesiveness, and gumminess scores in the cholesterol-reduced Cheddar cheese were significantly greater at 5 wk ripening than those in the control at 4 mo ripening. At the early stage of ripening, most flavor properties such as rancidity, bitterness, and off-flavor in the cholesterol-reduced cheese were greater. With ripening, however, those scores changed to similar or lower scores than those in the control. The present study indicated that the crosslinked β-CD treatment for cholesterol removal showed accelerated ripening effect on the properties of Cheddar cheese.     

红曲水牛乳软质干酪成熟特性的研究

红曲霉(Monascus purpureus Went.)是腐乳酿造中常用的菌种,将其作为表面发酵剂喷洒在干酪表面,研究该菌种对干酪成熟期间各理化指标的影响,结果表明:随着红曲霉在干酪表面生长和干酪成熟时间的延长,其含水量呈先低后高的趋势,最终维持在42%左右,可溶性氮p H4.6 SN和12%TCA SN分别高达35.8%和33.5%,其硬度、弹性、咀嚼性均随着成熟时间的延长而下降,干酪发酵成熟25 d便可得到最佳感官品质,其Monacolin K的含量为2.13 mg/100 g。