混合乳干酪生产工艺研究(2)混合乳干酪生产最佳工艺参数优化

本试验在已筛选出的发酵剂菌种、最佳凝乳酶和钙化合物的基础上,又综合考虑了影响混合乳(豆乳和牛乳)干酪的几大因素,即豆乳添加量,发酵剂添加量,乳酸钙添加量和凝乳酶添加量,由此优化出混合乳干酪生产的最佳工艺参数.结果表明最佳发酵剂为干酪乳杆菌99108+嗜热链球菌(11),最佳凝乳酶为皱胃酶,最佳钙化合物为乳酸钙,而70%大豆豆乳与30%牛乳混合,添加4%发酵剂,0.2%乳酸钙和0.015%皱胃酶则为最佳的工艺参数.     

类Cheddar豆乳干酪工艺参数的优化

研究了类Cheddar豆乳干酪的生产工艺并对其工艺参数进行了优化,对影响产品质量的主要因素进行了研究。通过正交试验,对发酵剂、豆乳、凝乳酶、CaCl2的最适添加量、凝乳时间和凝乳效果进行了研究和探讨。结果表明,添加豆乳20%、发酵剂3%、凝乳酶0.03%(活力为9 000 u/g)、CaCl20.06%时凝乳效果较好,在质构上与纯牛乳Cheddar干酪无明显差异。     

绿茶混合软质干酪质量控制研究

研究了绿茶粉豆乳混合干酪的制作工艺,试验结果表明,绿茶混合干酪的最佳工艺条件应为:绿茶粉加入量1%,豆乳添加量为20%,混合乳采用75℃杀菌15s,冷却后加入2%的发酵剂,其中保菌和嗜菌比例为2:3,发酵温度为35℃.当发酵乳pH值达到5.6时停止发酵,发酵后牛乳加入0.04?Clo<,2>和0.02%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65 min后经排乳清,加盐后熟化得到干酪产品,产品风味较好.出品率为9.12%.     

利用雅致放射毛霉制备水牛乳豆乳混合干酪工艺参数的优化

为提高水牛乳豆乳混合干酪品质,分别利用单因素试验及正交试验对以雅致放射毛霉为表面发酵剂制备水牛乳豆乳混合发酵干酪的工艺进行了优化。通过优化确定了水牛乳豆乳混合干酪的最佳发酵条件为豆乳添加量15%,程序升温至41℃,霉菌孢子喷雾浓度1×10^6 C FU /m L,成熟时间为30 d。在此优化的工艺条件下,能得到较好品质的霉菌干酪产品。     

豆奶干酪制备的影响因素研究

通过对豆奶干酪生产因素的研究,发现豆乳添加量、混合乳杀菌温度、发酵剂添加量、混合酶比例和CaCl2添加量等因素对豆奶干酪的产率都有影响,从而确定最佳工艺参数.实验结果表明,为了提高豆奶干酪的产率,同时保证豆奶干酪的品质,豆乳添加量为10%;杀菌条件为80℃、15 s;发酵剂添加量为2.00%;调酸pH为5.8;谷氨酰胺转胺酶与凝乳酶比例为4∶1;CaCl2添加量为0.06%;热缩温度为40℃;干酪切割时间为120min,切割大小为10mm.     

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。     

花生混合乳干酪的研制

用花生乳代替部分牛乳生产干酪,既强化了干酪风味又增强了干酪的保健功能,并可降低生产成本.本试验对花生乳比例、发酵剂添加量、氯化钙的添加量、凝乳酶添加量4个因素对凝乳效果的影响进行单因素试验,确定适合比例后,再采用L9(34)正交试验设计,通过凝乳效果、出品率和感官评价等进行极差分析,确定最佳工艺参数为:花生乳添加量为10 %,发酵剂添加量为0.03 %,氯化钙添加量为0.08 %,凝乳酶添加量为0.0025 %.     

直投式发酵剂在酸豆乳中的应用研究

研究以大豆为原料,研究直投式发酵剂(豆乳链球菌SY1.1)在酸豆乳生产中的应用研究。通过单因素和正交试验确定最佳发酵工艺:豆水比为1:9,蔗糖添加量为6%,发酵剂添加量0.1%,发酵温度46℃,发酵时间3 h。此工艺条件下发酵豆乳活菌数达3.1×108 cfu/m L,兼有豆香及发酵香,质地均匀,凝乳结实细腻,适合开发凝固型酸豆乳,或均质后作为搅拌型酸豆乳产品开发。     

半硬质干酪加工工艺条件的研究

通过单因素试验和正交优化试验,研究发酵剂添加量、CaCl2添加量、凝乳酶添加量、凝乳温度和盐水浓度对半硬质干酪感官品质的影响,从而得出加工半硬质干酪的最佳工艺条件。结果表明,其最佳工艺参数为发酵剂添加量5%、CaCl2添加量0.02%、凝乳酶添加量3.0 g/100 L、凝乳温度36 ℃、盐水质量分数18%。此最佳工艺条件下得到干酪的感官评分最高为93.25分,干酪产率为10.37%,含盐量为0.74%,含水量为43.58%。香味浓郁、组织细腻、软硬适度、呈现乳白色且有光泽。     

米黑毛霉凝乳酶制备切达干酪的工艺参数优化

为确定米黑毛霉凝乳酶制作切达干酪的最佳工艺条件,以感官评分和出品率为响应值,在单因素试验的基础上,采用响应面法对主要工艺参数进行了优化。试验得到的米黑毛霉凝乳酶制作切达干酪的最佳工艺参数为:酶添加量为2900.38SU/L、凝乳pH为6.2、CaCl_2添加量为0.04%、凝乳温度为34℃、发酵剂添加量为0.14%;在此条件下,干酪感官评分为(95.2±0.34),试验结果与预测值接近,证明模型拟合程度较好。     

Cheese pH, protein concentration, and formation of calcium lactate crystals

The occurrence of calcium lactate crystals (CLC) in hard cheeses is a continual expense to the cheese industry, as consumers fail to purchase cheeses with this quality defect. This research investigates the effects of the protein concentration of cheese milk and the pH of cheese on the occurrence of CLC. Atomic absorption spectroscopy was used to determine total and soluble calcium concentrations in skim milk (SM1, 8.7% total solids), and skim milk supplemented with nonfat dry milk (CSM1, 13.5% total solids). Calcium, phosphorus, lactic acid, and citrate were determined in cheeses made with skim milk (SM2, 3.14% protein), skim milk supplemented with ultrafiltered milk (CSM2, 6.80% protein), and nonfat dry milk (CSM3, 6.80% protein). Supplementation with nonfat dry milk increased the initial total calcium in CSM1 (210 mg/100 g of milk) by 52% compared with the total calcium in SM1 (138 mg/100 g of milk). At pH 5.4, soluble calcium concentrations in CSM1 were 68% greater than soluble calcium in SM1. In cheeses made from CSM2 and CSM3, total calcium was 26% greater than in cheeses made from SM2. As the pH of cheeses made from SM2 decreased from 5.4 to 5.1, the concentration of soluble calcium increased by 61.6%. In cheeses made from CSM2 and CSM3, the concentrations of soluble calcium increased by 41.4 and 45.5%, respectively. Calcium lactate crystals were observed in cheeses made from SM2 at and below pH 5.1, whereas CLC were observed in cheeses from CSM2 and CSM3 at and below pH 5.3. The increased presence of soluble calcium can potentially cause CLC to occur in cheese manufactured with increased concentrations of milk solids, particularly at and below pH 5.1.     

Glycolysis and related reactions during cheese manufacture and ripening

Fermentation of lactose to lactic acid by lactic acid bacteria is an essential primary reaction in the manufacture of all cheese varieties. The reduced pH of cheese curd, which reaches 4.5 to 5.2, depending on the variety, affects at least the following characteristics of curd and cheese: syneresis (and hence cheese composition), retention of calcium (which affects cheese texture), retention and activity of coagulant (which influences the extent and type of proteolysis during ripening), the growth of contaminating bacteria. Most (98%) of the lactose in milk is removed in the whey during cheesemaking, either as lactose or lactic acid. The residual lactose in cheese curd is metabolized during the early stages of ripening. During ripening lactic acid is also altered, mainly through the action of nonstarter bacteria. The principal changes are (1) conversion of L-lactate to D-lactate such that a racemic mixture exists in most cheeses at the end of ripening; (2) in Swiss-type cheeses, L-lactate is metabolized to propionate, acetate, and CO2, which are responsible for eye formation and contribute to typical flavor; (3) in surface mold, and probably in surface bacterially ripened cheese, lactate is metabolized to CO2 and H2O, which contributes to the increase in pH characteristic of such cheeses and that is responsible for textural changes, (4) in Cheddar and Dutch-type cheeses, some lactate may be oxidized to acetate by Pediococci. Cheese contains a low level of citrate, metabolism of which by Streptococcus diacetylactis leads to the production of diacetyl, which contributes to the flavor and is responsible for the limited eye formation characteristic of such cheeses.     

Gas-flushed packaging contributes to calcium lactate crystals in Cheddar cheese

Gas-flushed packaging is commonly used for cheese shreds and cubes to prevent aggregation and loss of individual identity. Appearance of a white haze on cubed cheese is unappealing to consumers, who may refrain from buying, resulting in lost revenue to manufacturers. The objective of this study was to determine whether gas flushing of Cheddar cheese contributes to the occurrence of calcium lactate crystals (CLC). Cheddar cheese was manufactured using standard methods, with addition of starter culture, annatto, and chymosin. Two different cheese milk compositions were used: standard (lactose:protein = 1.47, protein:fat = 0.90, lactose = 4.8%) and ultrafiltered (UF; lactose:protein = 1.23, protein:fat = 0.84, lactose = 4.8%), with or without adjunct Lactobacillus curvatus. Curds were milled when whey reached 0.45% titratable acidity, and pressed for 16 h. After aging at 7.2°C for 6 mo, cheeses were cubed (1 × 1 × 4 cm) and either vacuum-packaged or gas-flushed with carbon dioxide, nitrogen, or a 50:50 mixture of carbon dioxide and nitrogen, then aged for an additional 3 mo. Heavy crystals were observed on surfaces of all cubed cheeses that were gas-flushed, but not on cheeses that were vacuum-packaged. Cheeses without Lb. curvatus exhibited l(+)-CLC on surfaces, whereas cheeses with Lb. curvatus exhibited racemic mixtures of l(+)/d(−)-CLC throughout the cheese matrices. The results show that gas flushing (regardless of gas composition), milk composition, and presence of nonstarter lactic acid bacteria, can contribute to the development of CLC on cheese surfaces. These findings stress the importance of packaging to cheese quality.     

发酵剂对双蛋白干酪理化特性及风味的影响

在牛乳和添加豆乳(质量分数10%)的牛乳中分别使用筛选发酵剂与商品发酵剂进行切达干酪生产,并对成熟干酪的理化成分、质地、风味成分和感官特性进行分析。结果表明,豆乳的添加对干酪的质地、风味和感官特性均无不良影响,而应用筛选发酵剂L. lactis subsp. cremoris QH27-1和L. lactis subsp. lactis XZ3303生产双蛋白切达干酪对干酪的品质有一定的改善作用,可将其应用于双蛋白干酪生产中。     

Use of dry milk protein concentrate in pizza cheese manufactured by culture or direct acidification

Milk protein concentrate (MPC) contains high concentrations of casein and calcium and low concentrations of lactose. Enrichment of cheese milk with MPC should, therefore, enhance yields and improve quality. The objectives of this study were: 1) to compare pizza cheese made by culture acidification using standardized whole milk (WM) plus skim milk (SM) versus WM plus MPC; and 2) compare cheese made using WM + MPC by culture acidification to that made by direct acidification. The experimental design is as follows: vat 1 = WM + SM + culture (commercial thermophilic lactic acid bacteria), vat 2 = WM + MPC + culture, and vat 3 = WM + MPC + direct acid (2% citric acid). Each cheese milk was standardized to a protein-to-fat ratio of approximately 1.4. The experiment was repeated three times. Yield and composition of cheeses were determined by standard methods, whereas the proteolysis was assessed by urea polyacrylamide gel electrophoresis (PAGE) and water-soluble N contents. Meltability of the cheeses was determined during 1 mo of storage, in addition to pizza making. The addition of MPC improved the yields from 10.34 +/- 0.57% in vat 1 cheese to 14.50 +/- 0.84% and 16.65 +/- 2.23%, respectively, in vats 2 and 3 and cheeses. The percentage of fat and protein recoveries showed insignificant differences between the treatments, but TS recoveries were in the order, vat 2 > vat 3 > vat 1. Most of the compositional parameters were significantly affected by the different treatments. Vat 2 cheese had the highest calcium and lowest lactose contencentrations. Vat 3 cheese had the best meltability. Vat 1 cheese initially had better meltability than vat 2 cheese; however, the difference became insignificant after 28 d of storage at 4 degrees C. Vat 3 cheese had the softest texture and produced large-sized blisters when baked on pizza. The lowest and highest levels of proteolysis were found in vats 2 and 3 cheeses, respectively. The study demonstrates the use of MPC in pizza cheese manufacture with improved yield both by culture acidification as well as direct acidification.     

Compositional factors associated with calcium lactate crystallization in smoked Cheddar cheese

Previous researchers have observed that surface crystals of calcium lactate sometimes develop on some Cheddar cheese samples but not on other samples produced from the same vat of milk. The causes of within-vat variation in crystallization behavior have not been identified. This study compared the compositions of naturally smoked Cheddar cheese samples that contained surface crystals with those of samples originating from the same vat that were crystal-free. Six pairs of retail samples (crystallized and noncrystallized) produced at the same cheese plant on different days were obtained from a commercial source. Cheese samples were 5 to 6 mo old at the time of collection. They were then stored for an additional 5 to 13 mo at 4°C to ensure that the noncrystallized samples remained crystal-free. Then, the crystalline material was removed and collected from the surfaces of crystallized samples, weighed, and analyzed for total lactic acid, l(+) and d(−) lactic acid, Ca, P, NaCl, moisture, and crude protein. Crystallized and noncrystallized samples were then sectioned into 3 concentric subsamples (0 to 5 mm, 6 to 10 mm, and greater than 10 mm depth from the surface) and analyzed for moisture, NaCl, titratable acidity, l(+) and d(−) lactic acid, pH, and total and water-soluble calcium. The data were analyzed by ANOVA according to a repeated measures design with 2 within-subjects variables. The crystalline material contained 52.1% lactate, 8.1% Ca, 0.17% P, 28.5% water, and 8.9% crude protein on average. Both crystallized and noncrystallized cheese samples contained significant gradients of decreasing moisture from center to surface. Compared with noncrystallized samples, crystallized samples possessed significantly higher moisture, titratable acidity, l(+) lactate, and water soluble calcium, and significantly lower pH and NaCl content. The data suggest that formation of calcium lactate crystals may have been influenced by within-vat variation in salting efficacy in the following manner. Lower salt uptake by some of the cheese curd during salting may have created pockets of higher moisture and thus higher lactose within the final cheese. When cut into retail-sized chunks, the lower salt, higher moisture samples contained more lactic acid and thus lower cheese pH, which shifted calcium from the insoluble to the soluble state. Lactate and soluble calcium contents in these samples became further elevated at the cheese surface because of dehydration during smoking, possibly triggering the formation of calcium lactate crystals.     

大豆蛋白替代牛奶发酵的研究

本实验主要是利用大豆替代牛奶发酵，并研究了不同替代度的豆乳发酵情况，以及添加葡萄糖，庶糖，乳糖有脂肪等对大豆蛋白发酵的影响。     

A microfiltration process to maximize removal of serum proteins from skim milk before cheese making

Microfiltration (MF) is a membrane process that can separate casein micelles from milk serum proteins (SP), mainly beta-lactoglobulin and alpha-lactalbumin. Our objective was to develop a multistage MF process to remove a high percentage of SP from skim milk while producing a low concentration factor retentate from microfiltration (RMF) with concentrations of soluble minerals, nonprotein nitrogen (NPN), and lactose similar to the original skim milk. The RMF could be blended with cream to standardize milk for traditional Cheddar cheese making. Permeate from ultrafiltration (PUF) obtained from the ultrafiltration (UF) of permeate from MF (PMF) of skim milk was successfully used as a diafiltrant to remove SP from skim milk before cheese making, while maintaining the concentration of lactose, NPN, and nonmicellar calcium. About 95% of the SP originally in skim milk was removed by combining one 3 x MF stage and two 3 x PUF diafiltration stages. The final 3 x RMF can be diluted with PUF to the desired concentration of casein for traditional cheese making. The PMF from the skim milk was concentrated in a UF system to yield an SP concentrate with protein content similar to a whey protein concentrate, but without residuals from cheese making (i.e., rennet, culture, color, and lactic acid) that can produce undesirable functional and sensory characteristics in whey products. Additional processing steps to this 3-stage MF process for SP removal are discussed to produce an MF skim retentate for a continuous cottage cheese manufacturing process.     

Nonstarter lactic acid bacteria biofilms and calcium lactate crystals in Cheddar cheese

A sanitized cheese plant was swabbed for the presence of nonstarter lactic acid bacteria (NSLAB) biofilms. Swabs were analyzed to determine the sources and microorganisms responsible for contamination. In pilot plant experiments, cheese vats filled with standard cheese milk (lactose:protein = 1.47) and ultrafiltered cheese milk (lactose:protein = 1.23) were inoculated with Lactococcus lactis ssp. cremoris starter culture (8 log cfu/mL) with or without Lactobacillus curvatus or Pediococci acidilactici as adjunct cultures (2 log cfu/mL). Cheddar cheeses were aged at 7.2 or 10°C for 168 d. The raw milk silo, ultrafiltration unit, cheddaring belt, and cheese tower had NSLAB biofilms ranging from 2 to 4 log cfu/100 cm². The population of Lb. curvatus reached 8 log cfu/g, whereas P. acidilactici reached 7 log cfu/g of experimental Cheddar cheese in 14 d. Higher NSLAB counts were observed in the first 14 d of aging in cheese stored at 10°C compared with that stored at 7.2°C. However, microbial counts decreased more quickly in Cheddar cheeses aged at 10°C compared with 7.2°C after 28 d. In cheeses without specific adjunct cultures (Lb. curvatus or P. acidilactici), calcium lactate crystals were not observed within 168 d. However, crystals were observed after only 56 d in cheeses containing Lb. curvatus, which also had increased concentration of d(−)-lactic acid compared with control cheeses. Our research shows that low levels of contamination with certain NSLAB can result in calcium lactate crystals, regardless of lactose:protein ratio.     

发酵剂、氯化钙及凝乳酶添加量对白牦牛乳Mozzarella干酪质构的影响

以白牦牛乳为原料制作Mozzarella干酪,在单因素试验基础上采用Box-Behnken响应面法对发酵剂、CaCl_2、凝乳酶添加量进行优化,利用质构综合评分筛选最佳的工艺参数。结果表明,白牦牛乳Mozzarella干酪的最佳工艺参数为:发酵剂添加量0.24 g/L、CaCl_2添加量0.23 g/L、凝乳酶添加量0.04 g/L,此时白牦牛乳Mozzarella干酪质构综合评分为11.095,出品率为20.53%,感官评分为93.67。此工艺条件下制作的白牦牛乳Mozzarella干酪香味浓郁,质地均匀,软硬适度。