Calcium Supplementation of Cottage Cheese

Cottage cheese (100 g) provides only 6% of the calcium Recommended Daily Allowance for adults. Samples of fresh cheese were supplemented with calcium salts (chloride, lactate, or phosphate monobasic) to double the calcium content of the cheese to approximately 145 mg/100 g, and the effects of the supplementation on taste and microbial stability were studied. Supplementations did not affect pH or microbial stability during 21 d of refrigerated storage. Sensory evaluation results of a 12-member taste panel showed higher flavor and preference scores for control than for all supplemented samples (P<.05) but no difference in odor, color, or texture. Overall, chloride appeared to be preferable for calcium content supplementation because only .26% (wt/wt) of the salt was required to obtain the desired calcium content level and the mineral was evenly distributed in the cheese.     

Cottage Cheese from Ultrafiltered Skim Milk Retentates in Industrial Cheese Making

Ultrafiltered skim milk retentates were transported to a large industrial cottage cheese plant for milk supplementation leading to cottage cheese. The resulting industrial products were observed for composition, yields, whey component losses, and quality.Ten lots of small curd cottage cheese were made in vats containing up to 6593 kg skim milk. Retentate supplemented skim milks, concentrated approximately 10% (1.1:1) and 20% (1.2:1) in total protein, were very similar in initial composition to the controls. Mean cheese yield values from milks supplemented to 1.2:1 total protein were significantly higher than mean unsupplemented control milk values. Cheese yield efficiencies, per kilogram total solids, were also significantly higher in the retentate cheese but not when calculated per kilogram total protein.Total solids, total protein, and ash were higher in cottage cheese wheys from retentate supplemented cheese and were directly related to retentate supplementation concentration. Mean whey component loss per kilogram cheese exhibited significant decreases from milks of higher retentate supplementation. Retentate supplemented skim milk produced industrial cottage cheese of comparable quality to cheese made from unsupplemented control skim milks.     

Partial Deacidification and Demineralization of Cottage Cheese Whey by Nanofiltration

Nanofiltration (NF) membrane processing was investigated as a method for deacidifying and demineralizing cottage cheese whey (CCW) as function of pH 3.0 to 6.5 so that it could be used in ice cream and other frozen dairy desserts. Membrane flux values after 30 min processing ranged from 7.5 to 9.0 Lm^?2hr^?1. Total processing time to produce volume concentration ratio 3 (VCR3) retentate and diafiltration against 3 volumes of water to produce DNF3 retentate ranged from 87 to 93 min at pH 3–4.35 to 180 to 210 min at pH 5.5–6.5. DNF3 retentate contained 0.33% lactic acid, 0.65% ash, 11.55% lactose and 14.47% total solids. Membrane rejection of lactic acid ranged from 31% for VCR3 retentate to 67.2% for DNF3 retentate. Membrane rejection of minerals for VCR3 and DNF3 retentates was 30% and 71%, respectively.     

Modified Atmosphere Packaging to Maintain Direct-Set Cottage Cheese Quality

Direct-set cottage cheese packaged in barrier containers was flushed with 100% CO₂ 75% CO₂:25% N₂, 100% N_2, or air, and stored at 4°C for 28 days. Quality was assessed by sensory, microbiological, and chemical tests. No change was observed in headspace gas composition during storage. Psychrotrophic and lactic acid bacteria counts increased for air-treated samples, but counts for cottage cheese packaged under modified atmospheres remained unchanged. Product discoloration was not observed. Acidity increased over storage life, but lactic acid did not contribute towards increased acidity. Sensory characteristics of cottage cheese packaged under modified atmospheres remained satisfactory after 28 days, with 100% CO₂ best.     

Heat Transfer During the Washing of Small Curd Cottage Cheese

The heat transfer which occurs during the cooling of small curd cottage cheese during washing is mathematically modeled as a conduction process. The thermal diffusivity for curd was determined experimentally and shown to agree with predictions of correlations in the Literature. Heat transfer occurs rapidly in curd, and is a relatively less significant design basis for washing systems than mass transfer.     

山羊乳农家干酪加工中凝乳酶的筛选研究

选取5种凝乳酶应用于山羊乳农家干酪加工,通过不同凝乳酶在山羊乳农家干酪生产中的凝乳特性、干酪出品率及对干酪品质影响三方面试验研究,结果表明:液态小牛皱胃酶是山羊乳农家干酪加工的最佳凝乳酶,微生物凝乳酶次之,番木瓜蛋白酶不适合使用。     

Acceptability of Whey-Soy Drink Mix Prepared with Cottage Cheese Whey

Flavor score of commercially produced whey-soy drink mix containing 41% sweet whey solids was correlated with the lactic acid content of the dehydrated material (?.75). Experimental samples prepared with a 1:1 mixture of acid whey to sweet whey and neutralized acid whey showed lower initial flavor scores than a control prepared with only sweet whey. Both samples contained over 1% total lactate reported as lactic acid compared to .4% for the control. A sample prepared with a 1:5 mixture of acid to sweet whey contained .77% lactic acid. Flavor scores of this sample after 158 days storage at 37 C, although not significantly different from the control stored under similar conditions, showed a downward trend over time. Therefore, use of small amounts of acid whey in the formulation could lead to impaired storage stability as measured by flavor acceptability during prolonged storage under adverse conditions.     

Effect of On-Farm Heating and Storage of Milk on Cottage Cheese Yield

Effect of on-farm heat treatment of milk on cottage cheese yields was studied. Fresh, raw milk heated to 74°C for 10 s was cooled and stored for 7 days at 3°C. Control and experimental lots of milk were separated and pasteurized at 72°C for 15 s and were used to make cottage cheese. Microbiological, shelf-life, flavor, and texture studies showed the experimental lots of cheese were as good as or better than control lots. Yield of cottage cheese was significantly higher when made from heated milk.     

Cottage Cheese Whey Ultrafiltrate Produced by Hollow Fiber Ultrafiltration,

The composition and volume of ultrafiltrate produced by hollow fiber ultrafiltration of cottage cheese whey with the Bio-Rad Bio-Fiber 50 Miniplant were studied and fitted to models. Temperature, pH, and protein concentration of the feed cheese whey, the flow rate of the feed cheese whey through the Miniplant, and the pressure differential across the membranes were the independent variables in the model fitting. Feed whey temperature and pressure differential across the membranes were the most significant variables affecting the volume of ultrafiltrate produced. Surface plots of response were generated.     

Diacetyl as a Flavor Component in Full Fat Cottage Cheese

Diacetyl was detected at about 0.2 ppm using a two alternative forced choice procedure. Consumer acceptance for cottage cheese showed a small effect of added diacetyl, peaking at 1.0 ppm for aroma acceptance and flavor acceptance. Patterns of acceptance across diacetyl levels were similar for both frequent and infrequent consumers. Consumer acceptance tests conducted in a campus-based sensory testing facility gave similar results to tests conducted in a shopping mall, although the mall data were more variable.     

Acceptability of Reduced Sodium in Breads, Cottage Cheese, and Pickles

Salt was reduced in cottage cheese and white and whole wheat breads. Commercial dill and sweet pickles with reduced salt were also included. Acceptability of these foods was determined. Salt in bread was reduced 50% of the normal level with no significant effect on overall desirability. Cottage cheese with lower levels of salt was affected by salt content or contrast effect. No significant differences in mean scores for reduced sodium pickles were observed. Sodium and potassium content was determined by flame photometry. Reducing the salt content of foods alters the Na:K ratio.     

Effect of Proteolytic Activity of Streptococcus cremoris on Cottage Cheese Yields

Using only a proteinase-negative variant of Streptococcus cremoris UC310 to manufacture cottage cheese increased theoretical yields by 2.26% compared wth the proteinase-positive parent. Yield differences between positive and negative variants were strain dependent and not detected with variants of UC73 and UC97. Growth of proteinase-negative variants in bulk culture required pH control and addition of sufficient nitrogenous stimulant to provide carry-over activity into the cheese milk. Cultures developed normally when the bulk medium contained 5% of a blend of yeast extract and casein hydrolyzate. Proteinase-negative culture successfully completed acidification of cottage cheese milk after direct acidification to pH 5.2 with phosphoric acid. Lactic culture strain selection is suggested for maximizing product yields with proteinase-negative cultures.     

Partial Demineralization of Cottage Cheese Whey Using a Heat Treatment Process

Heat treatment of concentrated cottage cheese whey ultrafiltrate resulted in loss of calcium and phosphorus. Heat treatment at 100°C for 120 min resulted in a decrease of 21% of the calcium, 14% of the phosphorus, and 7% of the magnesium. Minimal browning of the concentrate occurs after 120 min. At 120°C, minimal browning had occurred after 60 min. Levels of calcium, phosphorus and magnesium had dropped by 41%, 36%, and 20%, respectively. Forty-eight percent of the calcium, 40% of the phosphorus and 26% of the magnesium were removed by heat treatment at 140°C for 24 min. At that point, browning was minimal. Losses of sodium and potassium were negligible for all cases. A first order rate expression was found to represent the precipitation process.     

Monitoring Chemical and Microbial Changes of Cottage Cheese using a Full-history Time-temperature Indicator

Cottage cheese (4% milkfat) was stored under three isothermal conditions (3, 9, and 15°C) and one varied temperature condition for the length of its useful shelf life–up to 32 days. Attached to each one-half pint carton were two full history, enzymatic based, time-temperature indicators (I-POINT models #4014 and #4021). Throughout the study quality attributes of the cottage cheese, as determined by chemical and microbial means, and the indicator progress were periodically monitored. The cheese spoiled due to growth of acid-forming bacteria under the warmer conditions and due to psychrotrophic bacteria under the coldest condition. Response of the I-POINT model 4014 was significantly related to changes in three of the quality attributes of the cottage cheese, specifically: pH, standard plate count when the cheese was stored at 8.8° C, and titratable acidity when the cheese was stored at 15.1° C.     

Liquid Drainage and Firmness in Full-fat, Lowfat, and Fat-free Cottage Cheese

Four different cottage cheese curds, as well as one full-fat (FFD), two lowfat (LF), and two fat-free (NF) dressings, were used to study liquid drainage’ and firmness of the products. After 10 hr at 4°C the volume of drained liquid after 1 and 7 days, was: FFD 77 to 38 mL, LF 59 to 2 mL, and NF 48 to 12 mL. Residual curd firmness was generally FFD > LF > NF. Both curd and dressing properties affected liquid drainage and firmness, indicating that using the same curd in the three cottage cheese varieties would likely result in variety differences in quality attributes.     

Evaluation of Alternative Methods to Increase Calcium Retention in Cottage Cheese Curd

The effect of several alternative methods including addition of rennet, addition of carrageenan and use of 2:1 (v/v) preconcentrated skim milk by ultrafiltration (UF) upon calcium retention, yield, composition and sensory properties of dry curd cottage cheese was investigated. Although each of the processing methods resulted in the manufacture of dry curd cottage cheese with different compositions and properties, none of them was satisfactory for increasing calcium retention. Added carrageenan bound additional whey proteins, added rennet interfered with curd syneresis and whey expulsion during cooking and use of UF preconcentrated skim milk resulted in an increase in yield, total solids and protein of the curd.     

Sensory Characteristics of Cottage Cheese Whey and Grapefruit Juice Blends and Changes During Processing

Studies were conducted to determine the sensory characteristics of pasteurized blends of cottage cheese whey and grapefruit juice (0%, 25%, 50%, 75% and 100% whey), and the effects of processing alternatives and storage at 3°C. A trained sensory panel rated six attributes (grapefruit, sweetness, sourness, astringency, cheesiness, saltiness). Cheesiness and saltiness increased, while sourness, astringency, sweetness, and grapefruit flavor decreased as the percentage of whey increased. Protein removal did not affect the sensory characteristics, but vacuum stripping reduced cheesiness and increased grapefruit flavor and sweetness. Lactose hydrolysis increased sweetness and decreased cheesiness in blends with more than 50% whey. The flavor of most blends was stable for 14 wk at 3°C.     

产细菌素乳酸菌的筛选及对农家干酪保质期的影响

从实验室保存的7 株乳酸菌中,经分离纯化,以金黄色葡萄球菌为指示菌,筛选获得1 株高产细菌素的菌株KLDS 1.0338,排除有机酸和过氧化氢的干扰以及蛋白酶敏感性实验,确定抑菌作用是由细菌素产生的。通过菌株形态学分析,生理生化及16S rDNA分析鉴定菌株KLDS 1.0338为干酪乳杆菌ATCC 334。进一步利用该菌株制作农家干酪,考察4 ℃贮藏期间干酪的变化,添加KLDS 1.0338干酪乳杆菌的实验组抑菌活性显著大于未添加KLDS 1.0338干酪乳杆菌组（P＜0.01）,实验组的pH值下降平缓,可以有效延长农家干酪的货架期,并保持产品原有的色泽、风味、质构等感官特性。     

Calcium Chelation and Other Pretreatments for Flux Improvement in Ultrafiltration of Cottage Cheese Whey

Cottage cheese whey was treated to minimize effects of calcium on membrane fouling during ultrafiltration in a stirred Amicon cell. The treatments used were stepwise pH adjustment from 4.5 to 1.5; chelation of calcium with EDTA or citric acid; calcium chelation followed by pH adjustment to 2.5; and calcium replacement with sodium by ion exchange. All treatments resulting in elimination of free calcium improved the flux. Highest flux increase (53%) in the 8hr processing runs was for citric acid (I.25 meq/one meq Ca) after pH adjustment to 2.5. Addition of CaC1₂ decreased the flux. Confirmatory experiments with DDS-Lab 20 equipment showed 25% flux increase after treatment with either EDTA (one meq/one meq Ca) or citric acid (I.25 meq/one meq Ca) with pH adjusted to 2.5.     

Lactose Hydrolysis in Ultrafiltration-Treated Cottage Cheese Whey with Various Whey Protein Concentrations

Lactose hydrolysis by soluble Aspergillus oryzaeβ-galactosidase was studied in (a) ultrafiltration (UF) permeate containing varying concentrations of isolated β-lactoglobulin or serum albumin; (b) UF retentate at four protein levels; and (c) cottage cheese whey during the UF treatment in an Amicon stirred cell unit. The rate and extent of lactose hydrolysis achieved in all the conditions studied was independent of protein concentration in the whey preparations used. After 6 hr of the simultaneous UF-lactose hydrolysis process at room temperature, similar hydrolysis level was achieved in the retentate as in the batch hydrolysis process. The average degree of hydrolysis in the permeate was 52.6%. The retentate added to milk at room temperature hydrolysed 93% of the lactose in 15 hr.