Colour of hard cheese 2. Factors of influence and relation to compositional parameters

 Colour properties of hard cheeses, which included mature Vorarlberger Bergk?se (n=141) as well as a set of Emmental cheeses monitored periodically during ripening, were evaluated by tristimulus reflectance measurements. After transformation of the tristimulus primaries into the recently proposed one-dimensional Yellowness index, colour measures were related to selected compositional parameters by multivariate statistical methods. Both multiple regression and principal component regression showed that cheese body colour is mainly affected by qualitative properties of the fat phase which, in turn, are heavily influenced by seasonal deviations. Additional minor sources of variation include the total solids content as well as measures reflecting changes induced by cheese maturation. Received: 15 July 1996     

Colour of hard cheese 2. Factors of influence and relation to compositional parameters

Colour properties of hard cheeses, which included mature Vorarlberger Bergkäse (n=141) as well as a set of Emmental cheeses monitored periodically during ripening, were evaluated by tristimulus reflectance measurements. After transformation of the tristimulus primaries into the recently proposed one-dimensional Yellowness index, colour measures were related to selected compositional parameters by multivariate statistical methods. Both multiple regression and principal component regression showed that cheese body colour is mainly affected by qualitative properties of the fat phase which, in turn, are heavily influenced by seasonal deviations. Additional minor sources of variation include the total solids content as well as measures reflecting changes induced by cheese maturation.     

Judge selection for hard and semi-hard cheese sensory evaluation

During a five month period, 34 potential panellists were subjected to 21 selection tests (triangular test, threshold evaluation, ranking test and stimulus recognition test) based on taste, aroma and textural characteristics of cheese. Standardised available ricotta cheese was used as a substrate in taste and aroma tests, while commercially available cheese was utilised to evaluate candidate performance in textural characteristic tests. A combination of procedures (binomial, sequential and bi-plot) allowed the definition of homogeneous subsets of candidates suitable for different analysis. The binomial approach allowed the last performing candidates to be identified while the sequential procedure enhanced our understanding of their skills. To make the selection criteria more coherent the performance parameters were objectively derived from the array of tests. Candidates were classified into three groups, depending on their capabilities, and the different discrimination power of the tests was highlighted through bi-plots.     

中式绿茶硬质干酪工艺的研究

研究了绿茶粉风昧干酪的制作工艺,结果表明,绿茶风昧干酪的最佳工艺条件为绿茶粉加入量1%,原料乳采用75℃,15s杀菌,冷却后加入2%的发酵剂,其中保菌和嗜菌比例为1:2,发酵温度为35℃。当发酵乳pH值至5.8时停止发酵,在发酵乳中加入0.02%的CaCl_2和1.5g/L的混合凝乳酶(动物凝乳酶和微生物凝乳酶比例为4:1),35℃条件下凝乳1h后经排乳清,加盐后熟化得到干酪产品,产品膻味大大降低,出品率为9.78%。     

Content and distribution of biogenic amines in Dutch-type hard cheese

Content of biogenic amines (BA; histamine, tyramine, tryptamine, putrescine, 2-phenylethylamine, cadaverine, spermidine, spermine) and counts of microorganisms (total aerobic and facultative anaerobic mesophilic microorganisms, TAC; lactic acid bacteria, LAB; coliforms; total anaerobic microorganisms, TAN; yeasts + moulds), were evaluated within the ripening interval of 1–6 months in Dutch-type hard cheese, produced by two different producers (the cheeses designated as R30 and R45) using pasteurized milk and different starter cultures (designated as R30-FD and R30-CH in the case of the R30 cheeses). The cheeses from the two producers differed in their fat content (30% and 45% of fat in dry matter, respectively).     

新疆酸凝硬质干酪成熟条件的研究

研究了成熟温度、成熟时间和包装方式等因素对新疆酸凝硬质干酪成熟的影响。分别以干酪中丁二酮质量分数和感官综合评分为指标,确定优化的成熟条件为气调包装、15℃成熟30d。在该成熟条件下,随着干酪成熟时间的延长,干酪中的酯类、醛类、芳香环类、烷烃和烯烃类物质质量分数呈现增加的趋势,而醇类和酸类物质则呈现降低的趋势;在结构方面成熟干酪的分子空穴更大,蛋白质结构变得更加松散。     

硬质干酪国家卫生标准修订的研究

根据卫生部“八五”食品卫生工作计划和全国卫生标准分委会制（修）订国家卫生标准项目计划要求,全国乳与乳制品卫生标准制（修）订工作协作组对已颁布实施了１５年之久的硬质干酷国家卫生标准ＧＢ５４２０－８５进行了修订。在感官指标中,取消了百分制评定等级规定;在外观、组织状态、滋气味各项目中进行了规范要求,在理化指标中取消了食盐、汞指标,增加了食品添加剂指标,提出水分指标限值≤４３％,脂肪≥２５％,食品添加剂     

硬质干酪加工工艺中关键技术参数的研究与优化

以cheddar干酪加工工艺为基础,针对工艺中影响产品质量的工艺参数进行试验分析,找出对产品质量最有影响的关键因素.通过单因素初步试验,进而进行了多因素交叉影响试验,采用LSR法进行多重比较分析.分析结果表明:发酵剂添加量3.0%(质量分数),熟化终止pH值为6.5,保温搅拌温度40℃,保温搅拌时间40 min为适宜的工艺参数,所制得的干酪质量达到统一的标准并且稳定.     

硬质发酵干酪加工设备简述

在简要说明我国发展干酪生产必要性的基础上,以切达干酪加工生产为例,从原奶的预处理、凝块的形成和加工、乳清排放以及质构化和盐化、灌装和压榨、包装和储存等5个方面详细介绍了国内外硬质干酪产品加工设备类型和使用情况,以期推动我国干酪加工设备的国产化进程。     

发酵剂用量对硬质蒙古干酪风味变化的影响

以不同发酵剂使用量制作了一种硬质蒙古干酪,对干酪成熟过程中的风味变化和微生物多样性进行了研究。当发酵剂使用量为1.0 g/L原料乳时,挥发性风味化合物的组分更为丰富,风味更加均匀适中,具有更好的风味体验。在干酪成熟早期,嗜热链球菌和保加利亚乳杆菌生长趋势相同,但到中后期,嗜热链球菌生长速度趋缓,而保加利亚乳杆菌生长速度相对较快。     

Polyphosphates as inhibitors of surface mould growth on hard cheese during ripening

A novel treatment using polyphosphates to protect cheeses against superficial mould growth was assayed. The treatments were: control commercial paint with natamycin (I), commercial paint based on polyvinyl–water (II), immersion in a saturated solution of polyphosphate (III), immersion and commercial paint (IV), commercial paint of polyphosphate solutions (V) and immersion and commercial paint of a saturated solution of polyphosphates (VI). The cheeses were ripened for 6 months. Superficial mould growth was inhibited in groups IV and VI when compared to cheeses from the control group (I). Statistical sensory analysis made between cheeses from groups IV and I (control) showed no significant differences.     

不同发酵剂对牦牛乳硬质干酪品质的影响

以新鲜牦牛乳为原料,分别添加嗜温、嗜热和混合(嗜温∶嗜热=1∶1)三种发酵剂制作硬质干酪,研究在1~180 d成熟过程中,不同类型发酵剂制作的干酪中蛋白降解和ACP(酸性磷酸酶)对其品质的影响。结果表明:牦牛乳硬质干酪成熟过程中发挥作用的ACP主要来自发酵剂,且干酪中蛋白降解受ACP影响显著,ACP与PPN(多肽氮)呈强正相关性(r=0.720),与CN(酪蛋白氮)和PN(蛋白氮)呈强负相关性。三种干酪PPN在60~120 d均保持稳定状态。不同类型的发酵剂对干酪蛋白降解强弱不同,过强或过弱均会影响到干酪的品质,嗜温发酵剂对干酪蛋白降解最弱,该干酪风味比较清淡;嗜热发酵剂对干酪蛋白降解能力最强,该发酵剂制作的干酪苦味较重,但组织状态较好;混合发酵剂对蛋白降解适中,该干酪发酵风味浓郁,组织状态较佳。      

Microbiological and biochemical properties of canestrato pugliese hard cheese supplemented with bifidobacteria

Canestrato Pugliese cheeses from ewe milk were produced according to a traditional protocol and by adding 7.0 log10 cfu of fresh cells per gram of Bifidobacterium bifidum Bb02, Bifidobacterium longum Bb46, or both species. The traditional technology was modified slightly to favor the survival of probiotic microorganisms. After 56 d of ripening, the survival of B. bifidum Bb02 and B. longum Bb46 was 6.0 and 5.0 log10 cfu/g, respectively. After 19 d cheeses contained ca. 7.0 log10 cfu/g of bifidobacteria. Compared to traditional cheese, the addition of bifidobacteria seemed to support the growth and survival of mesophilic lactobacilli and Streptococcus thermophilus, used as starter, during ripening. No significant differences were observed in the main chemical composition, and only a slightly higher concentration of acetic acid was found in cheeses with bifidobacteria added. On the contrary, alpha- and beta-galactosidase activities were markedly more pronounced in the presence of bifidobacteria, especially with B. bifidum Bb02. In contrast with traditional cheese, the lactose was completely hydrolyzed in cheeses made with bifidobacteria. Urea-PAGE electrophoresis of the pH 4.6-soluble and pH 4.6-insoluble N fractions did not show appreciable variations. Only the reversed-phase-HPLC analysis of the pH 4.6-soluble N showed a slightly more complex profile in the presence of bifidobacteria. This finding was in agreement with the higher value of the pH 4.6-soluble N/total N ratio and with the more pronounced amino-, imino-, and dipeptidase activities found in all the cheeses with the bifidobacteria added, especially B. bifidum Bb02. No differences were found in the free amino acid and free fatty acid contents. The amino acids glutamic acid, valine, proline, leucine, and lysine and the fatty acids butyric, caproic, capric, and oleic acids were found at the highest concentrations. The sensory evaluation did not show significant differences, and Canestrato Pugliese cheeses were characterized by small and uniformly distributed eyes, were pale yellow, had an elastic consistency and a Pecorino-like smell, were very salty, and tended to be moderately piquant.     

Acceleration of cheese ripening at elevated temperature. An estimation of the optimal ripening time of a traditional Argentinean hard cheese

The effect of elevated ripening temperature on physicochemical, biochemical and sensory characteristics in Reggianito Argentino cheese was evaluated to determine the optimal time for cheese ripening at 18 °C that ensures typical cheese characteristics. Cheeses ripened at 12 or 18 °C and 85% relative humidity were analysed at 2, 4 and 6 months. Seventy-eight variables (as determined by urea-PAGE, RP-HPLC of the water-soluble at pH 4.6 fraction, free amino acids, free fatty acids and sensory analysis) were considered for the principal component analysis. The statistical analysis allowed determination of the optimal time for ripening Reggianito Argentino cheese at 18 °C, which was ranged between 2 and 3 months. In conclusion, the results obtained were not only useful in characterising the ripening of an Argentinean hard cheese, but also in evaluating the effect of an increase of ripening temperature on the main physicochemical, biochemical and sensory changes of Reggianito Argentino cheese.     

Behaviour of Escherichia coli strains during semi-hard and hard raw milk cheese production

The behaviour of two Escherichia coli strains, one with a high and the other with a low thermotolerance phenotype, was investigated during production and ripening of Swiss semi-hard and hard raw milk cheese. In semi-hard cheese, counts of E. coli increased during production, before a log-linear decrease occurred during ripening, with a faster rate of reduction in core than in rind samples, and faster reduction of the more heat-sensitive strain in rind samples. Nevertheless, at the end of semi-hard cheese ripening, E. coli were present at least at 1.3 log₁₀ cfu g⁻¹ in rind samples and remained detectable by enrichment of core samples. During the first day of hard cheese production, both E. coli strains were almost completely inactivated. Detection by enrichment was possible in one of twelve spiked cheeses after 16 weeks, indicating the potential of a thermotolerant E. coli strain to survive until the end of ripening.     

发酵剂用量对硬质蒙古干酪蛋白质、脂类水解和微观结构的影响

该文通过添加不同发酵剂用量制作了3种硬质蒙古干酪,并对硬质蒙古干酪的理化性质、蛋白质和脂肪水解程度、微观结构等进行了研究。结果表明,随着发酵剂用量增多,除D-乳酸含量外,其他理化指标均随发酵剂用量的增大而减小;粗蛋白质和粗脂肪的含量减少;pH 4.6-可溶性氮（SN）含量和12%三氯乙酸（TCA）-SN含量均增加,表明干酪中蛋白质和脂肪的水解程度增大;游离氨基酸和游离脂肪酸的含量增加,表明干酪的风味物质增多。随着发酵剂用量的增多,干酪酸化速度加快,质地相对松散。最终确定发酵剂使用量为1.0 g/L,在此条件下,脂肪和蛋白质的水解程度适中,游离氨基酸种类丰富,能够满足干酪风味化合物生成的需求。     

A survey of the microbiological quality of Sharri,a hard mountain cheese from Kosovo

The microbiological quality of a hard mountain unpasteurised sheep cheese from three randomly selected manufacturing locations in Kosovo was investigated. Forty‐eight samples of row milk, coagulum, 8–10 days ripening cheese and of ready to eat cheese (45‐days in brine) were tested. Seventy‐five per cent of raw milk samples failed to comply with EU regulation 853/2004. All of coagulum and ripened cheese failed to comply with EU regulation 2073/2005 on process hygiene criteria. Despite the high incidence of coagulase‐positive staphylococci even in the final product [>10⁵ colony‐forming units (cfu)/g], Staphylococcal enterotoxin was detected in none of the samples and no samples were positive for Listeria monocytogenes and Salmonella enteritidis.     

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。