不同因素对羊奶干酪凝乳效果的影响

对影响羊奶干酪凝乳效果主要因素进行了研究。结果表明,原料乳浓度越大,凝乳效果越好;杀菌条件以巴氏杀菌或高温短时杀菌效果较好;添加发酵剂使乳酸度达24～25°T效果较好;CaCl2添加量以0.01%～0.03%为宜。用犊牛皱胃酶或羔羊皱胃酶作为凝乳酶,可得到较好的凝乳效果。     

Colby干酪优化参数研究

对影响Colby干酪加工主要因素进行了研究。结果表明,原料乳浓度越大,凝乳效果越好;杀菌条件以巴氏杀菌或高温短时杀菌效果较好;调整酸度为24～28oT效果较好;CaCl2添加量为0.06%为宜;用小牛皱胃酶或羔羊皱胃酶作为凝乳酶,可得较好的凝乳效果。     

巴戟天乙醇提取物的油脂抗氧化性和抗菌活性

采用不同浓度乙醇溶液提取巴戟天后,将其提取物用于抗氧化活性和抗菌活性的实验研究。结果表明,巴戟天乙醇提取物具有油脂抗氧化作用,并且随添加量的增加抗氧化效果越好,且乙醇溶液浓度为80%时提取物的抗氧化效果最好。巴戟天乙醇提取物对细菌的抗菌效果较好,但对于酵母和霉菌的抑制作用弱。     

4种杀菌剂在小麦淀粉生产过程中的应用研究

选用4种在食品生产中杀菌效果较好的杀菌剂作用于小麦淀粉乳,以菌落总数、大肠菌群、霉菌和酵母为指标研究4种杀菌剂对产品的杀菌效果。结果表明,使用稳定性过氧化氢生产小麦淀粉乳时最佳杀菌条件为添加量10.0%杀菌2 h;百宜杀菌剂和二氧化氯的最适添加量分别为4.0%和7.2 mg·L^-1,二者作用于小麦淀粉乳的时间均与稳定性过氧化氢相同。4种杀菌剂中稳定性过氧化氢、百宜杀菌剂和二氧化氯在小麦淀粉生产过程中均具有较好的杀菌作用,但乳酸链球菌素在小麦淀粉生产过程中对大肠菌群的杀菌效果均不佳,不建议在生产中使用。     

Nisin延长低脂再制干酪保质期的应用

Nisin已广泛应用于食品保质期的研究中,本试验研究在贮存过程中,Nisin对低脂再制干酪细菌、肠杆菌、霉菌和酵母菌的抑菌效果及pH的变化。在低脂再制干酪样品中,空白样品贮藏到5个月时,样品变质不可食用,添加0.2%、0.3%Nisin的样品到6个月时,细菌总数、肠杆菌、酪霉菌和酵母菌合格,而添加0.2%Nisin、0.3%Nisin抑菌效果差异不显著,因此添加0.2%Nisin为宜。随着贮藏期时间的增加,pH显著增加。     

BEKAPLUS FS对酸奶品质的影响

主要研究了BEKAPLUS FS对酸奶感官品质的影响以及对酸奶主要污染菌霉菌、酵母菌的抑制效果。结果表明,在酸奶中添加BEKAPLUS FS能够有效抑制酸奶的后酸化,添加浓度为0.025%,6℃条件下酸奶保质期可延长8 d左右。BEKAPLUS FS对霉菌、酵母菌亦有显著的抑制作用。综合酸奶感官品质和生产要求,BEK-APLUS FS的添加量为0.025%时最佳。     

花生乳牛乳混合干酪的工艺研究

对影响混合乳干酪凝乳效果的主要因素进行了研究,试验结果表明:当花生乳添加量为20%,发酵酸度为24°T,皱胃酶添加量为0．30%,CaCl_2添加量为0．06%时凝乳效果较好。     

双乙酸钠对蛋糕防霉保鲜效果研究

通过稀释平板法定期检测蛋糕保藏过程中霉菌总数变化,研究了不同浓度的双乙酸钠对不同种类蛋糕防霉效果的影响.实验证明:双乙酸钠在普通面糊类蛋糕中的最佳防霉添加量为0.4%,此时蛋糕在常温下的霉菌超标时间为14 d,比不添加防腐剂的蛋糕延长10 d.0.4%双乙酸钠对三种不同配方蛋糕的防霉效果不尽相同,普通蛋糕优于戚风蛋糕,海绵蛋糕最差.     

制麦过程中乳酸菌对霉菌的抑制作用

本文从乳酸菌添加时间和培养时间两个方面研究了乳酸菌对出炉麦芽表面霉菌的抑制作用并考察添加后对出炉麦芽常规指标是否有不利影响.结果表明,在湿浸阶段添加效果较好,浸麦结束和发芽第一天添加的抑制效果不明显.将划线培养后的乳酸菌直接加入,添加量为（1.0-2.0）＆#215;108个/克绝干大麦时,乳酸菌对出炉麦芽表面霉菌产生了明显的抑制作用,随着菌种培养时间的延长,抑菌效果呈下降趋势.添加一定量乳酸菌后对麦芽一般理论指标无不利影响.     

不同因素对羊奶干酪出品率的影响

对影响羊奶干酪出品率主要因素进行了研究。结果表明,原料乳浓度越大,羊奶干酪出品率越高;杀菌条件以巴氏杀菌或高温短时杀菌效果较好;CaCl2添加量以0.02%～0.03%为宜;用犊牛皱胃酶或羔羊皱胃酶为凝乳酶,羊奶干酪的出品率最高。     

Effect of Imitation or Filled Dairy Products

United States consumers are eating more fat than ever, but they are eating less animal fat. Per capita consumption of animal fat dropped 34% since 1960, and vegetable fat consumption increased by 77%. The shift to imitation dairy products is reflected in dairy product surpluses and resulting downward pressure on dairy product prices.The imitation product that threatens the dairy industry most is imitation cheese. The 205 million pounds of imitation cheese marketed in 1984 was 44% of US Department of Agriculture price support purchases of cheese.Average retail prices for various types of imitation cheese are 16 to 32% lower than natural cheese prices; pizza with imitation cheese averages 14% less in price than natural cheese pizza of the same brand. Imitation cheese takes up 16% of the shredded cheese shelf space, 2% of the unshredded and process cheese shelf space, and pizza made with imitation cheese has gained more than half the pizza shelf space in the United States.The following strategies are recommended to counter the imitation problem: 1) reduce price advantage of imported casein through negotations with the European Economic Community to reduce export subsidies: 2) work for clearer, more prominent labeling of imitation dairy products; 3) put more emphasis on butter-margarine blend products, which compete more directly with margarine than butter; 4) use more of the $197 million annual promotion funds from farmer checkoffs for promoting cheese. Buyer response to cheese promotion is three times the response from a similar investment in fluid milk promotion.     

An attempt to produce low fat cephalotyre (Ras) cheese of acceptable quality

Two trials were carried out to produce low fat Ras cheese with acceptable organoleptic properties. In the first trial, cheese milk containing 1%, 1·5% or 2% fat and including CMC or carrageenan at levels of 0·1% and 0·02%, respectively, was used in cheese making. Control cheese was also made from milk containing 4% fat. Cheese without added stabilizers and containing lower fat levels than the control cheese had a flat flavour and tough rubbery body throughout ripening. The addition of both stabilizers improved the body characteristics of low fat cheese but did not affect flavour development in cheeses made from 1% and 1·5% fat milk and only slightly enhanced flavour intensity in cheese made from 2% fat milk.In the second trial, cheese milk of 1% or 1·5% fat with added 0·02% carrageenan was used for the preparation of Ras cheese curd. The resultant curd was then mixed with 2% of a starter culture containing S. diacetylactis and L. casei with 10 ml of 0·05% MnCl₂ solution for each kilogram of curd or reduced glutathione at a level of 100 mg/kg curd. The additives enhanced flavour intensity, improved body characteristics and accelerated the formation of both soluble nitrogenous compounds and Free Volatile Fatty Acids.     

Evaluation of Yield and Quality of Cheddar Cheese Manufactured from Milk with Added Whey Protein Concentrate

Cheddar cheese was produced from whole milk with blends of whey protein concentrates added. Two whey protein concentrate powders containing 35 or 55% protein were each reconstituted to a 15% (wt/wt) suspension and heat treated at 70°C for 15 min. Addition of the denatured whey protein concentrate suspension to the milk was at 5 or 10% by weight of the milk. Addition of reconstituted partially denatured whey protein concentrate increased cheese yields from 1.4 to 6.2% above those of the control on a 63% solids basis. The only significant (P<.05) increase in yield was from the 55% whey protein concentrate suspension at 10% replacement by weight of the milk. The correlation coefficient between percent denaturation in the whey protein concentrate and yield in this cheese was .62. Experimental cheese had decreased fat and total solids contents and increased total nitrogen, ash, and salt. Fat reduction varied from 4.3 to 18.2% below the control cheese, and total solids were from 1.7 to 8.9% below the control cheeses. Total nitrogen values of experimental cheese were from .73 to 5.64% above the control. Cheeses were evaluated organoleptically; more flavor defects were associated with increased whey protein concentrate in the experimental cheese. The most common criticism of the experimental cheese was an atypical (unclean) cheese flavor.     

Short communication: Norbixin and bixin partitioning in Cheddar cheese and whey

The Cheddar cheese colorant annatto is present in whey and must be removed by bleaching. Chemical bleaching negatively affects the flavor of dried whey ingredients, which has established a need for a better understanding of the primary colorant in annatto, norbixin, along with cheese color alternatives. The objective of this study was to determine norbixin partitioning in cheese and whey from full-fat and fat-free Cheddar cheese and to determine the viability of bixin, the nonpolar form of norbixin, as an alternative Cheddar cheese colorant. Full-fat and fat-free Cheddar cheeses and wheys were manufactured from colored pasteurized milk. Three norbixin (4% wt/vol) levels (7.5, 15, and 30 mL of annatto/454 kg of milk) were used for full-fat Cheddar cheese manufacture, and 1 norbixin level was evaluated in fat-free Cheddar cheese (15 mL of annatto/454 kg of milk). For bixin incorporation, pasteurized whole milk was cooled to 55°C, and then 60 mL of bixin/454 kg of milk (3.8% wt/vol bixin) was added and the milk homogenized (single stage, 8 MPa). Milk with no colorant and milk with norbixin at 15 mL/454 kg of milk were processed analogously as controls. No difference was found between the norbixin partition levels of full-fat and fat-free cheese and whey (cheese mean: 79%, whey: 11.2%). In contrast to norbixin recovery (9.3% in whey, 80% in cheese), 1.3% of added bixin to cheese milk was recovered in the homogenized, unseparated cheese whey, concurrent with higher recoveries of bixin in cheese (94.5%). These results indicate that fat content has no effect on norbixin binding or entrapment in Cheddar cheese and that bixin may be a viable alternative colorant to norbixin in the dairy industry.     

超高压处理对干酪质构的影响

研究超高压(Ultra High Hydrostatic Pressure,HHP;200,600 MPa/10min)处理对5种市售干酪的硬度、黏着性、弹性、内聚性、咀嚼性和回复性6个功能特性的影响。结果显示,5种干酪在200 MPa处理时,其黏着性、弹性、内聚性、回复性差异不显著(P0.05),即较低压力处理对干酪的质构影响不大;超高压处理后,干酪的硬度和耐咀性分别降低31%,39%,且压力越大降低越显著(P0.05);高压处理后蓝纹、稀奶油干酪的内聚性分别增加了21%,15%;帕马森、切达干酪经超高压处理其各个性质基本无显著变化,而马索里拉、蓝纹、稀奶油干酪的各个功能性均有显著差异,说明超高压处理对干酪质构的影响与水分含量有关,即水分含量越高的干酪其质构受超高压处理变化越显著。     

Manufacture of processed cheese from Iraqi white soft cheese

Processed cheese was made from different samples of Iraqi white soft cheese by adding 3.5% emulsifying salts and 15–25% water depending on the chosen type of processed cheese. Arabic gum was used to firm the cheese at a rate of 0.08%. Total solids ranged from 46.8–43.4% in the firm and spread types, respectively. Laboratory processed cheese gave excellent quality compared with local processed cheese.     

Use of cold microfiltration retentates produced with polymeric membranes for standardization of milks for manufacture of pizza cheese

Pizza cheese was manufactured with milk (12.1% total solids, 3.1% casein, 3.1% fat) standardized with microfiltered (MF) and diafiltered retentates. Polymeric, spiral-wound MF membranes were used to process cold (<7°C) skim milk, and diafiltration of MF retentates resulted in at least 36% removal of serum protein on a true protein basis. Cheese milks were obtained by blending the MF retentate (16.4% total solids, 11.0% casein, 0.4% fat) with whole milk (12.1% total solids, 2.4% casein, 3.4% fat). Control cheese was made with part-skim milk (10.9% total solids, 2.4% casein, 2.4% fat). Initial trials with MF standardized milk resulted in cheese with approximately 2 to 3% lower moisture (45%) than control cheese (∼47 to 48%). Cheese-making procedures (cutting conditions) were then altered to obtain a similar moisture content in all cheeses by using a lower setting temperature, increasing the curd size, and lowering the wash water temperature during manufacture of the MF cheeses. Two types of MF standardized cheeses were produced, one with preacidification of milk to pH 6.4 (pH6.4MF) and another made from milk preacidified to pH 6.3 (pH6.3MF). Cheese functionality was assessed by dynamic low-amplitude oscillatory rheology, University of Wisconsin MeltProfiler, and performance on pizza. Nitrogen recoveries were significantly higher in MF standardized cheeses. Fat recoveries were higher in the pH6.3MF cheese than the control or pH6.4MF cheese. Moisture-adjusted cheese yield was significantly higher in the 2 MF-fortified cheeses compared with the control cheese. Maximum loss tangent (LT_max) values were not significantly different among the 3 cheeses, suggesting that these cheeses had similar meltability. The LT_max values increased during ripening. The temperature at which the LT_max was observed was highest in control cheese and was lower in the pH6.3MF cheese than in the pH6.4MF cheese. The temperature of the LT_max decreased with age for all 3 cheeses. Values of 12% trichloroacetic acid soluble nitrogen levels were similar in all cheeses. Performance on pizza was similar for all cheeses. The use of MF retentates derived with polymeric membranes was successful in increasing cheese yield, and cheese quality was similar in the control and MF standardized cheeses.     

Characterization of Cheese Curd Ripened with Penicillium caseicolum for Producing a Flavor Concentrate

Camembert cheese was prepared from homogenized milk containing veal oral lipase and ripened in a loose curd form to speed up the ripening process. Traditional hooped cheese was a control. Free fatty acid titer increased from 58 μmole in the fresh cheese to 359 μmole in control cheese and 2,289 μmole/g of cheese fat in loose curd cheese. After 3 wk of ripening, the cheese had 70% of its total protein as water soluble protein as compared to 39% in the hooped cheese. Polyacrylamide gel electrophoresis showed 86% of α_S1-caseins and 35% of β-casein had been degraded in the loose curd cheese. Sensory analysis demonstrated that the loose curd process rapidly produced cheese with intense flavor.     

MOLD GROWTH AND PRESENCE OF AFLATOXIN IN SOME TURKISH CHEESES

Twenty-five random fresh market samples of Van herby cheese and pickled white cheese were examined for molds and aflatoxins. The mean total mold count in Van herby cheese was 2.50 × 10⁵/g; in pickled white cheese it was 4.95 × 10⁴/g. The mycoflora on the cheeses were determined. In all cheeses, over 65% of molds were Penicillium species . Aspergillus made up 0 to 1.6 % and 2.6 % to 4.0 % of the mold on pickled white cheese and Van herby cheese, respectively. Other isolated molds belonged to Mucor, Geotrichum and Trichoderma genera. None of the samples contained aflatoxins and none of the 6 Aspergillus isolates was an aflatoxin producer .     

Improvement of texture and structure of reduced-fat Cheddar cheese by exopolysaccharide-producing lactococci

The objective of this study was to evaluate the effect of capsular and ropy exopolysaccharide (EPS)-producing strains of Lactococcus lactis ssp. cremoris on textural and microstructural attributes during ripening of 50%-reduced-fat Cheddar cheese. Cheeses were manufactured with added capsule- or ropy-forming strains individually or in combination. For comparison, reduced-fat cheese with or without lecithin added at 0.2% (wt/vol) to cheese milk and full-fat cheeses were made using EPS-nonproducing starter, and all cheeses were ripened at 7°C for 6 mo. Exopolysaccharide-producing strains increased cheese moisture retention by 3.6 to 4.8% and cheese yield by 0.28 to 1.19 kg/100 kg compared with control cheese, whereas lecithin-containing cheese retained 1.4% higher moisture and had 0.37 kg/100 kg higher yield over the control cheese. Texture profile analyses for 0-d-old cheeses revealed that cheeses with EPS-producing strains had less firm, springy, and cohesive texture but were more brittle than control cheeses. However, these effects became less pronounced after 6 mo of ripening. Using transmission electron microscopy, fresh and aged cheeses with added EPS-producing strains showed a less compact protein matrix through which larger whey pockets were dispersed compared with control cheese. The numerical analysis of transmission electron microscopy images showed that the area in the cheese matrix occupied by protein was smaller in cheeses with added EPS-producing strains than in control cheese. On the other hand, lecithin had little impact on both cheese texture and microstructure; after 6 mo, cheese containing lecithin showed a texture profile very close to that of control reduced-fat cheese. The protein-occupied area in the cheese matrix did not appear to be significantly affected by lecithin addition. Exopolysaccharide-producing strains could contribute to the modification of cheese texture and microstructure and thus modify the functional properties of reduced-fat Cheddar cheese.