胃蛋白酶和姜汁混合制作干酪的研究

采用L16（4^5）正交实验设计，以胃蛋白酶和姜汁混合制作契达干酪，分别测定了随乳清排出的蛋白质含量、凝乳时间、校正产率和感官特性，最后得出以体积分数为0．2％的胃蛋白酶和0．2％的姜汁混合制干酪，可制得各个指标都较好的干酪。     

鱼油替代菜籽油对蛋鸡生产性能及脂质代谢的影响

试验共设四个组，对照组含3％菜油，试验组分别含2％菜油＋1％鱼油、1％菜油＋2％鱼油和3％鱼油，研究日粮鱼油替代菜籽油对蛋鸡产蛋性能、蛋品质和脂质代谢的影响。结果表明，蛋黄中ALA、DHA含量以2％鱼油添加组最高，分别比对照组提高32．88％（P〈0．05）和22．49％（P〉0．05），EPA含量以1％鱼油添加组最高，比对照组提高13．48（P〈0．05）；添加鱼油组蛋黄TC含量升高（P〉0．05），TG变化不明显，MDA含量升高（P〉0．05）；血清TC含量升高，以3％鱼油添加量组最高，比对照组提高3．55％（P〈0．05），2％、3％鱼油添加组TG含量降低，分别比对照组下降12，52％（P〉0．05）和51．18％（P〈0．05）；血清HDL—C含量升高，LDL—C含量降低，SOD、MDA含量有所降低，蛋重以2％和3％鱼油添加组显著低于对照组（P〈0．05），蛋壳强度分别比对照组提高13．79％（P〉0．05）、41．72％（P〈0．05）和32．37％（P〉0．05）。研究表明，蛋鸡日粮中添加鱼油可以提高ω-3PUFA在蛋黄中的沉积，影响机体的脂质代谢，同时伴随脂质过氧化物合成增加，但对产蛋性能无明显影响。综合各种指标，蛋鸡日粮中以2％的鱼油添加量为佳。     

利用响应面法优化重制干酪的制作工艺

以契达干酪为原料,采用响应面法对重制干酪的制作工艺进行优化。优化后乳化盐的使用量分别为:焦磷酸钠2%,柠檬酸钠1.5%,三聚磷酸钠2%,重制干酪的凝胶强度为528.1 g/cm2,感官评分4.8分。     

乳化盐及加工条件对再制干酪质地及理化特性的影响

研究乳化盐及加工条件对再制干酪质地及理化特性的影响。结果表明,增加乳化盐的用量、融化温度和延长搅拌时间明显降低了再制干酪的融化性(p<0.01),不同种类乳化盐在相同添加水平下,制得样品的融化性:焦磷酸钠>磷酸氢二钠>柠檬酸钠;增加乳化盐的用量和延长搅拌时间制得的样品硬度显著增加、黏着性显著减小(p<0.01),提高融化温度制得的样品硬度增加,但其黏着性差异不显著(p>0.01)。在添加量相同的情况下,柠檬酸钠制得样品的硬度和黏着性最大,焦磷酸钠使样品的硬度和黏着性最小。     

含大豆分离蛋白的干酪在成熟过程中化学组成和感官特性的变化

分析了不同大豆分离蛋白含量的干酪在成熟期化学组成（水分、蛋白质、脂肪、灰分）的变化，评价了其感官特性。结果表明，质量分数为5%大豆分离蛋白的干酪与纯牛乳干酪相比，其感官特性最佳。     

常温贮藏燕麦干酪食品的研发

研究开发了常温贮藏燕麦干酪食品,利用SAS软件Box-Behnken对产品关键工艺参数进行了优化设计。常温贮藏燕麦干酪食品的最佳配方为：选择1个月快速成熟切达干酪和Mozzarella干酪（按照1∶2配比）共100g,加入11．46％燕麦,1．2％NaCl、2．27％乳化盐（柠檬酸钠）,大豆分离蛋白添加量为3．76％,45％纯净水,融化温度86℃,保温搅拌8 min。同时,燕麦干酪食品在90天的理化、微生物指标,测项目均符合国标要求。     

大豆分离蛋白对涂抹型再制干酪质构的影响

添加大豆蛋白可降低涂抹型再制干酪的成本,但也会对再制干酪的质构产生一定的影响。设计优选配方组合4因素3水平正交试验,应用TA-XT2i型物性分析仪考察了添加大豆蛋白后再制干酪产品的质构变化,使用Statistix 8．0统计分析软件对试验结果做正交试验极差分析。结果表明4个因素不同水平的9组正交试验结果的差异性显著（p〈0．05）,4个因素对硬度的影响排序为D〉C〉A〉B;对剪切功的影响排序为D〉A〉B〉C;对黏着性的影响排序为A〉B〉D〉C;对感官评价的影响排序为A〉D〉C〉B。最后对最优组再次测定各项指标,得到最佳的组合为大豆蛋白添加量6％,黄油添加量10％,乳化盐添加量1．5％,加水量50％。     

豆奶软质干酪的研制

通过不同豆奶比例、发酵剂添加量、氯化钙添加量对凝乳特性的影响进行研究，确定了豆奶软质干酪的制作工艺为：原料奶-杀菌-冷却（32℃）-混合（加入豆奶比例为20％）-加发酵剂（0．20％）-加氯化钙（0．06％）-加凝乳酶-切割-排乳清-压榨-盐渍-喷霉-熟化（后发酵）-包装，可得口感风味良好的白霉成熟干酪。     

Mozzarella再制干酪辅料及其工艺条件的选择

研究了利用Mozzarella天然干酪制备再制干酪的工艺。通过单因素试验和正交试验,确定了最佳辅料配方和工艺条件：成熟期为1个月和4个月的Mozzarella干酪以2：1混合,复配乳化盐（添加柠檬酸钠量0．80％、多聚磷酸钠为0．08％、焦磷酸钠为0．15％）,乳清浓缩蛋白用量6％,黄油用量15％,加水量20％,乳化水浴温度100℃,乳化时间7min,乳化转速1000r／min。利用GC—MS法对再制干酪中主要挥发性风味化合物进行分析共鉴定出23种风味物质其中烃类7．8％;醇类9．56％;醛类4．81％;酮类5．82％;酸类22．91％;酯类41．1％;酚类0．269％及二甲基砜7．73％。     

玉米胚芽蛋白Cheddar干酪生产工艺的优化

以玉米胚茅蛋白为添加辅料,研究了玉米胚芽蛋白添加量、Ca^2＋浓度、切割大小、盐浓度四个工艺参数对玉米胚芽Cheddar干酪品质的影响,利用响应面分析法确定了最佳工艺参数。结果表明,胚芽蛋白添加量为4．28％,Ca^2＋浓度为0．04％,切割大小为9．05mm3,盐浓度为1．62％时,生产的玉米胚芽Cheddar干酪具有干酪特有的滋味和气味,软硬适度、香味醇厚、营养丰富。     

Texture and Microstructure of Block Type Processed Cheese with Formulated Emulsifying Salt Mixtures

Block-processed Ras cheese was produced with two salt mixtures: (1) Na-diphosphate+Na-polyphosphate+Na-tripolyphosphate in ratios 40 : 50 : 10, 30 : 40 : 30 & 30 : 30 : 40 and (2) Na-polyphosphate+Na-citrate+Na-orthophosphate+Na-diphosphate in ratios 50 : 20 : 20 : 10, 40 : 10 : 20 : 30 & 30 : 10 : 20 : 40. Commercial salts Joha SE and PZO were used for comparison, respectively. Texture profile analysis and microstructure (LM and TEM) of resultant cheeses were studied. Chewiness, gumminess, adhesiveness, and hardness showed a significant difference and the cheese samples exhibited higher values during storage. The values were highest in the samples stored at room temperature. Light microscopy photographs indicated different emulsification degree with various emulsifying salt mixtures. These observations were confirmed with the image analysis and TEM. Among the entire treatments, mixture (1) in ratio 30 : 40 : 30 and mixture (2) in ratio 40 : 10 : 20 : 30 gave the best and close texture to the commercial salts and can be recommended in the production of block processed cheese.     

分步酶解法制备酶改性切达干酪粉

介绍了一种分步酶解法制备酶改性干酪粉(EMC)的方法。第一步,用不同的蛋白酶与肽酶混合酶对切达干酪浆进行蛋白水解,筛选出最佳水解产物。第二步,用不同的脂肪酶对最佳水解产物进行脂肪水解。将得到的酶解液喷雾干燥获得两种粉末状的EMC产品A和B,并与商品切达EMC进行比较分析。本研究获得的两种EMC产品的总游离氨基酸及总游离脂肪酸质量分数均比商品EMC高,各种游离氨基酸质量分数也普遍高于商品EMC。EMC产品A感官指标得分较高,不同链长的脂肪酸比例与商品EMC接近。     

溶菌酶处理发酵剂加速干酪成熟的研究

以pH、蛋白质降解、脂肪酸含量变化及干酪的感官特征为指标,研究了溶菌酶处理发酵剂对干酪成熟的影响。结果表明:实验组干酪的pH在整个成熟期处于对照组1(添加2%发酵剂)干酪和对照组2(添加2.5%发酵剂)的pH之间,表明通过溶菌酶处理发酵剂可明显抑制干酪成熟期间的产酸量;添加溶菌酶处理发酵剂可加速干酪中蛋白质分解和乳脂肪的降解;感官评价结果表明,添加溶菌酶处理发酵剂可提高干酪风味,在相同的成熟时间实验组干酪的质地也较对照组好。     

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。     

Lipolysis and proteolysis in Ragusano cheese during brine salting at different temperatures

The influence of temperature (12, 15, 18, 21, and 24 degrees C) of saturated brine on lipolysis and proteolysis in 3.8-kg blocks of Ragusano cheese during 24 d of brining was determined. Twenty-six 3.8-kg blocks were made on each day. The cheese making was replicated on 3 different days. All blocks were labeled and weighed prior to brining. One block was sampled and analyzed prior to brine salting. Five blocks were placed into each of 5 different brine tanks at different temperatures. One block was removed from each brine tank after 1, 4, 8, 16, and 24 d of brining, weighed, sampled, and analyzed. Both proteolysis and lipolysis in Ragusano cheese increased with increasing brine temperature (from 12 to 24 degrees C), with the impact of brine temperature on proteolysis and lipolysis becoming progressively larger. Proteolysis was highest in the interior of the blocks where salt in moisture content was lowest and temperature had more impact on proteolysis in the interior position of the block than the exterior position. However, the opposite was true for lipolysis. The total free fatty acid content was higher and temperature had more impact on lipolysis at the exterior position of the block where salt in moisture was the highest. This effect of increased salt concentration on lipolysis was confirmed with direct salted cheeses in a small follow-up experiment. Lipolysis increased with increasing salt in the moisture content of the direct salted cheeses. It is likely that migration of water-soluble FFA from the brine into the cheese and from the interior portion of the cheese to the exterior portion of the cheese also contributed to a higher level of FFA at the exterior portion of the blocks. As brine temperature increased the profile of individual free fatty acids released from triglycerides changed, with the proportion of short-chain free fatty acids increasing with increasing brine temperature. This effect was largest at high salt in moisture content.     

Effect of Trisodium Citrate Concentration and Soy Cheese on Meltability of Pizza Cheese

The objective of this study was to determine the effect of soy cheese (tofu) and trisodium citrate (TSC) concentration on physicochemical properties of pizza cheese. The results indicated that fat and FDM contents of pizza cheese increased significantly with increased proportion of TSC, while moisture and protein decreased but not significantly (P < 0.05). On the other hand, the fat, FDM, and protein content decreased with increased proportion of tofu, while moisture increased. The melting area and melting degree indicated that melting properties of pizza cheese decreased significantly, as the concentration of TSC increased. Furthermore, increase approximately 5 and 10% tofu in the blends with 0.5% TSC or 10% tofu in the blends with 1% TSC affected notable decrease in melting properties. Among each level of tofu, oiling off area showed significant increase with increasing TSC. Increase in tofu proportion as well as different TSC concentration resulted in decrease in free oil. The control cheese with 1% TSC (CC2C) had maximum oiling off, and with increase in tofu proportion there was a corresponding reduction (P < 0.05) in the oiling off area. It was observed that increase approximately 10% tofu in the blends with 0.5% TSC cause marked reduction in oiling off area by approximately 47%. There was rapid increase in oiling off area during the early stage of cooking. According to observation, free oil formation of cheese with 1% TSC (C2C) was higher than that of the cheese with 0.5% TSC (C1C), especially during 2.5 to 10 min (P > 0.05). Oiling off area of treatments decreased independently of trisodium citrate prolong cooking as the proportion of tofu increased.     

Determination of fat,protein, moisture,and salt content of Cheddar cheese using mid-infrared transmittance spectroscopy

The objective of our work was to develop and evaluate the performance of a rapid method for measuring fat, protein, moisture, and salt content of Cheddar cheese using a combination mid-infrared (MIR) transmittance analysis and an in-line conductivity sensor in an MIR milk analyzer. Cheddar cheese was blended with a dissolving solution containing pentasodium triphosphate and disodium metasilicate to achieve a uniform, particle-free dispersion of cheese, which had a fat and protein content similar to milk and could be analyzed using a MIR transmittance milk analyzer. Annatto-colored Cheddar cheese samples (34) from one cheese factory were analyzed using reference chemistry methods for fat (Mojonnier ether extraction), crude protein (Kjeldahl), moisture (oven-drying total solids), and salt (Volhard silver nitrate titration). The same 34 cheese samples were also dissolved using the cheese dissolver solution, and then run through the MIR and used for calibration. The reference testing for fat and crude protein was done on the cheese after dispersion in the dissolver solution. Validation was done using a total of 36 annatto-colored Cheddar cheese samples from 4 cheese factories. The 36 validation cheese samples were also analyzed using near-infrared spectroscopy for fat, moisture, and the coulometric method for salt in each factory where they were produced. The validation cheeses were also tested using the same chemical reference methods that were used for analysis of the calibration samples. Standard error of prediction (SEP) values for moisture and fat on the near-infrared spectroscopy were 0.30 and 0.45, respectively, whereas the MIR produced SEP values of 0.28 and 0.23 for moisture (mean 36.82%) and fat (mean 34.0%), respectively. The MIR also out-performed the coulometric method for salt determination with SEP values of 0.036 and 0.139 at a mean level of salt of 1.8%, respectively. The MIR had an SEP value of 0.19 for estimation at a mean level of 24.0% crude protein, which suggests that MIR could be an easy and effective way for cheese producers to measure protein to determine protein recovery in cheese making.     

Proteolytic and lipolytic changes during the ripening of a Spanish craft goat cheese (Armada variety)

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.     

Influence of emulsifying salts on the textural properties of nonfat process cheese made from direct acid cheese bases

The objective of this study was to investigate the influence of several types of emulsifying salts (ES) on the texture of nonfat process cheese (NFPC). Improperly produced nonfat cheese tends to exhibit several problems upon baking including stickiness, insufficient or excessive melt, pale color upon cooling, formation of a dry skin (skinning) often leading to dark blistering, and chewy texture. These attributes are due to the strength and number of interactions between and among casein molecules. We propose to disrupt these interactions by using suitable emulsifying salts (ES). These ES chelate Ca and disperse caseins. Stirred curd cheese bases were made from skim milk using direct acidification with lactic acid to pH values 5.0, 5.2, and 5.4, and ripened for 1 d. Various levels of trisodium citrate (TSC; 0.5, 1, 1.5, 2, 2.5, 3, and 5%), disodium phosphate (DSP; 1, 2, 3, and 4%), or trisodium phosphate (TSP; 1, 2, 3, and 4%) were blended with the nonfat cheese base. Cheese, ES, and water were weighed into a steel container, which was placed in a waterbath at 98°C and then stirred using an overhead stirrer for 9 min. Molten cheese was poured into plastic containers, sealed, and stored at 4°C for 7 d before analysis. Texture and melting properties were determined using texture profile analysis and the UW-Melt-profiler. The pH 5.2 and 5.4 cheese bases were sticky during manufacture and had a pale straw-like color, whereas the pH 5.0 curd was white. Total calcium contents were approximately 400, 185, and 139 mg/100 g for pH 5.4, 5.2, and 5.0 cheeses, respectively. Addition of DSP resulted in NFPC with the lowest extent of flow, and crystal formation was apparent at DSP levels above 2%. The NFPC manufactured from the pH 5.0 base and using TSP had reduced melt and increased stickiness, whereas melt was significantly increased and stickiness was reduced in NFPC made with pH 5.4 base and TSP. However, for NFPC made from the pH 5.4 cheese and with 1% TSP, the pH value was >6.20 and crystals were observed within a few days. Use of TSC increased extent of flow up to a maximum with the addition of 2% ES for all 3 types of cheese bases. Addition of high levels of TSC to the pH 5.2 and 5.4 cheese bases resulted in increased stickiness. Similar pH trends for attributes such as extent of flow, hardness, and adhesiveness were observed for both phosphate ES but no consistent pH trends were observed for the NFPC made with TSC. These initial trials suggest that the pH 5.0 cheese base was promising for further research and scale-up to pilot-scale process cheese making, because cheeses had a creamy color, reasonable melt, and did not have high adhesiveness when TSC was used as the ES. However, the acid whey produced from the pH 5.0 curd could be a concern.     

开菲尔直投式发酵剂在益生菌干酪生产中的应用研究

该研究主要将开菲尔粒制备成直投式发酵剂应用于干酪的生产。 以FD-DVS R-704商业干酪发酵剂制作的干酪为对照,对其 理化指标、挥发性香气成分、质构特性和感官指标进行测定与评价。 结果表明,与对照干酪相比,开菲尔干酪的水分含量、pH4.6-可溶 性氮（SN）及12%三氯乙酸（TCA）-SN的含量极显著增高（P＜0.01）,pH值极显著低（P＜0.01）,而粗脂肪比例和总游离氨基酸（TFAA） 含量无显著差异（P＞0.05）,不饱和脂肪酸（UFA）含量显著增高（P＜0.05）;醇类和酯类物质的种类增多;硬度和咀嚼性极显著降低（P＜0.01）,胶黏性极显著增大（P＜0.01）,内聚性和弹性无明显差异（P＞0.05）;开菲尔粒益生菌干酪呈乳白色,表面有光泽,不仅具 有干酪特有的滋味和气味,且具有开菲尔发酵乳的特有风味,带有适宜的酒香味。