Pre-treatment methods of Edam cheese milk. Effect on the whey composition

Edam cheese milk was subjected to high-heat treatment (HH), ultrafiltration (UF) and microfiltration (MF). The effect on the recovery yield and the composition of whey was studied. Traditional Edam process was used as a reference. HH reduced the whey protein concentration of milk and whey, but the recovery from milk to whey was not affected. Reduction of whey proteins was the highest (28%) with MF treatment, during which 15% was lost in the MF permeate and 13% was co-precipitated with the cheese curd. Co-precipitation of the whey proteins was the highest (84%) with ultrafiltered milk. MF and UF treatments produced 22% less whey with increased whey protein concentration. Elevation of the cheese milk protein concentration by microfiltration or ultrafiltration decreased the recovery of fat in whey. None of the treatments decreased the residual casein concentration in whey. The protein composition was altered by UF and MF treatments, which significantly increased the caseinomacropeptide content of total protein in whey. The whey was processed into whey protein concentrate powders. The amino acid composition of the whey protein concentrate produced from microfiltration process was significantly different from the others.     

Feta cheese texture: the effect of caprine and ovine milk concentration

Feta cheese was produced commercially with different caprine to ovine milk ratios. Milk fat concentrations, moisture and salt contents were similar for all the batches. However, the hardness and adhesive characteristics of the cheeses differed in relation to the milk ratio. The hardness of the cheese appeared to be correlated to increased goat milk content. Cryo-scanning electron microscopy (cryo-SEM) of the cheese samples showed that feta cheese with a higher proportion of caprine milk had a more compact and less porous appearance than feta produced from purely ovine milk. This difference in cheese structure helps to explain the difference in hardness between the samples.     

Valuation of milk composition and genotype in cheddar cheese production using an optimization model of cheese and whey production

A mass balance optimization model was developed to determine the value of the κ-casein genotype and milk composition in Cheddar cheese and whey production. Inputs were milk, nonfat dry milk, cream, condensed skim milk, and starter and salt. The products produced were Cheddar cheese, fat-reduced whey, cream, whey cream, casein fines, demineralized whey, 34% dried whey protein, 80% dried whey protein, lactose powder, and cow feed. The costs and prices used were based on market data from March 2004 and affected the results. Inputs were separated into components consisting of whey protein, ash, casein, fat, water, and lactose and were then distributed to products through specific constraints and retention equations. A unique 2-step optimization procedure was developed to ensure that the final composition of fat-reduced whey was correct. The model was evaluated for milk compositions ranging from 1.62 to 3.59% casein, 0.41 to 1.14% whey protein, 1.89 to 5.97% fat, and 4.06 to 5.64% lactose. The κ casein genotype was represented by different retentions of milk components in Cheddar cheese and ranged from 0.715 to 0.7411 kg of casein in cheese/kg of casein in milk and from 0.7795 to 0.9210 kg of fat in cheese/kg of fat in milk. Milk composition had a greater effect on Cheddar cheese production and profit than did genotype. Cheese production was significantly different and ranged from 9,846 kg with a high-casein milk composition to 6,834 kg with a high-fat milk composition per 100,000 kg of milk. Profit (per 100,000 kg of milk) was significantly different, ranging from $70,586 for a high-fat milk composition to $16,490 for a low-fat milk composition. However, cheese production was not significantly different, and profit was significant only for the lowest profit ($40,602) with the κ-casein genotype. Results from this model analysis showed that the optimization model is useful for determining costs and prices for cheese plant inputs and products, and that it can be used to evaluate the economic value of milk components to optimize cheese plant profits.     

Specific effect of high-pressure treatment of milk on cheese proteolysis

The extent of primary and secondary proteolysis of cheeses made from raw (RA), pasteurized (PA, 72 degrees C, 15 s) or pressure-treated (PR, 500 MPa, 15 min, 20 degrees C) goats' milk was assessed. Modifications in cheese-making technology were introduced to obtain cheeses with the same moisture content, and thus studied per se the effect of milk treatment on cheese proteolysis.The PR milk cheese samples were differentiated from RA and PA milk cheeses by their elevated beta-lg content, and by the faster degradation of alphas1-, alphas2- and beta-CN throughout ripening. Non-significant differences were found in either pH 4.6 soluble-nitrogen or trichloracetic acid soluble-nitrogen contents of cheeses. However, the pasteurization of milk decreased the free amino acid production in cheese. The RA milk cheeses had the highest amount of proline and the lowest concentrations of serine, tyrosine, arginine and alpha-aminobutyric acid, whereas PR milk cheese showed higher levels of arginine.     

The effect of plasmin activity and cold storage of cheese milk on the composition, ripening and functionality of mozzarella-type cheese

The effects of casein hydrolysis by plasmin on composition, ripening and functionality in mozzarella-type cheese were studied. Milk was stored at 4°C for 0, 24 and 48 h, with and without added plasmin, before batch pasteurization and the manufacturing of mozzarella-type cheese. In parallel experiments, the effects of incubation of milk with added plasmin for 2 h at 37°C prior to cheese manufacture and of an increase in the level of rennet added during cheesemaking were studied. Plasmin addition adversely affected the rennet coagulation properties of the milk and led to increased (two- to three-fold) plasmin activity in cheese and greater plasmin-associated hydrolysis of β-casein to γ-caseins during ripening. Melted cheese flow rate and stretchability increased over ripening and melting time decreased, but functional properties were not affected by either plasmin activity or cold storage. Overall, neither plasmin activity (at the levels studied) nor cold storage greatly affected the composition or functionality of mozzarella-type cheese.     

热处理与均质压力对扣碗酪凝乳质构的影响

热处理与均质是牛奶处理的必须工艺,这两个因素对凝乳形成、蛋白变性等方面都有影响,这些因素也影响到扣碗酪的凝乳质构性质。本文应用物性测定的方法,对热和均质扣碗酪的凝乳质构中的硬度、粘着性和凝聚性的影响进行了分析,发现牛奶的均质压力与热处理温度之间对扣碗酪的凝乳质构性质没有交互作用,选择低温热处理以及低均质压力能够得到比较好的凝乳质构。硬度和粘着性对整体饱满度的影响比较大,相关系数分别达到0.679和0.743。凝聚性对扣碗酪的整体饱满度影响不大。     

Permeation behaviour of buffalo milk Cheddar cheese whey during ultrafiltration

The permeation behaviour of buffalo-milk Cheddar cheese whey during ultrafiltration was studied. Buffalo-milk Cheddar cheese whey was adjusted to various pH levels ranging from 3.0 to 7.2 and ultrafiltration was carried out at 50° C to a level of 95% volume reduction by maintaining 1.75 and 0.50 bar inlet and outlet pressures, respectively. It was observed that the retentate had a minimum ash content of 3.17 % on a dry matter basis at pH 3.0 as against 6.23% when ultrafiltered at pH 7.2. As the pH was decreased from 7.2 to 3.0, the ash content of the retentate was drastically reduced. The calcium and phosphorus content of the retentate also varied significantly with change in pH, being minimal at pH 3.0 and increasing significantly with increase in pH of the whey. The yield of protein and lactose in the final retentate also varied with the pH of the whey. The permeate had a total solids content ranging from 5.65 to 5.78%. The maximal ash content of 0.59% was observed in the permeate when ultrafiltered at pH 3.0. As the whey pH increased, the ash content in the permeate decreased significantly. The total protein content of the permeate ranged from 0.18 to 0.23%. Most of the protein was observed to be non-protein nitrogen. Polyacrylamide gel electrophoresis showed the presence of-lactalbumin and traces of-lactoglobulin in the permeate. The lactose content of the permeate ranged from 4.98 to 5.02%. The results indicate that the final composition of whey protein concentrate can be altered by monitoring the volume reduction as well as by adjusting the whey pH before ultrafiltration.

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Das Permeationsverhalten von Molke aus Büffelmilch-Cheddar während der Ultrafiltration

Zusammenfassung Es wurde das Permeationsverhalten von Molke aus Büffelmilch-Cheddar während der Ultrafiltration studiert, und zwar bei verschiedenen pH-Werten von 3,0 bis 7,2 bei 50 °C mit einer Volumenreduktion von 95% bei 1,75 bzw. 0,50 Innen- bzw. Außendruck. Es wurde beobachtet, daß das Rententat eine minimale Trockensubstanz von 3,17% bei pH 3,0 gegenüber 6,23% bei pH 7,2 hatte. Durch die pH-Abnahme von 7,2 auf 3,0 wurde auch der Aschegehalt des Retentats drastisch reduziert. Der Ca- und P-Gehalt des Retentats variierte ebenfalls signifikant mit der pH-Veränderung, gleichfalls der Protein- und Lactose-Gehalt. Das Permeat hatte einen Gesamtgehalt von 5,65 bis 5,78%. Der maximale Aschegehalt von 0,59% wurde in dem bei pH 3,0 ultrafiltrierten Permeat festgestellt; der Aschegehalt nahm signifikant ab, wenn das pH der Molke zunahm. Der Proteingehalt des Permeaters lag zwischen 0,18 und 0,23%, wobei das meiste Nicht-Proteinstickstoff war. Polyacrylamidgelelektrophorese zeigte die Gegenwart von -Lactalbumin und Spuren-Lactglobulin im Permeat. Der Lactosegehalt rangierte von 4,98 bis 5,02%. Die Ergebnisse zeigen, daß die endgültige Zusammensetzung des Molkenkonzentrates sowohl durch die Volumenverringerung als auch durch die pH-Einstellung der Molke vor der Ultrafiltration eingestellt werden kann.

     

An investigation of the plasmin–plasminogen system in caprine milk and cheese

The variability in activities of plasmin (PL) and plasminogen (PG) in bulk milk samples from different breeds of goats was investigated. The mean PL activity was higher (19.56±4.72 U g⁻¹) than in milk from other ruminant species, while PG-derived activity was, surprisingly, lower (12.84±5.31 U g⁻¹). No significant differences in PL and PG levels were observed among goat breeds, but PL activity and PL/PG ratio increased in late lactation compared with early lactation. PL activities in pilot-scale curds (acid or rennet) and in some Italian cheeses made from caprine milk were also measured. Generally, acid curds and cheeses had lower residual PL and PG-derived activities than rennet curds and semi-hard cheeses. In addition, the PL/PG ratio was greatly reduced in rennet curds, due to a higher extent of PG-derived activity. Measurement of proteolysis of β-casein in curds confirmed that more extensive proteolysis occurred in rennet curds, which had higher residual PL activities.     

Effect of frozen storage on the proteolytic and rheological properties of soft caprine milk cheese

Freezing and long-term frozen storage had minimal impact on the rheology and proteolysis of soft cheese made from caprine milk. Plain soft cheeses were obtained from a grade A goat dairy in Georgia and received 4 storage treatments: fresh refrigerated control (C), aged at 4°C for 28 d; frozen control (FC), stored at −20°C for 2 d before being thawed and aged in the same way as C cheese; and 3-mo frozen (3MF), or 6-mo frozen (6MF), stored at −20°C for 3 or 6 mo before being thawed and aged. Soft cheeses had fragile textures that showed minimal change after freezing or over 28 d of aging at 4°C. The only exceptions were the FC cheeses, which, after frozen storage and aging for 1 d at 4°C, were significantly softer than the other cheeses, and less chewy than the other frozen cheeses. Moreover, after 28 d of aging at 4°C, the FC cheeses tended to have the lowest viscoelastic values. Slight variation was noted in protein distribution among the storage treatment, although no significant proteolysis occurred during refrigerated aging. The creation and removal of ice crystals in the cheese matrix and the limited proteolysis of the caseins showed only slight impact on cheese texture, suggesting that frozen storage of soft cheeses may be possible for year-round supply with minimal loss of textural quality.     

Isolation and characterisation of caseinmacropeptide from bovine,ovine, and caprine cheese whey

Based on the thermostability of caseinmacropeptide (CMP) and on the differences in molecular weight of its polymeric and monomeric forms, we have developed a method of isolating CMP from whey protein concentrate (WPC) and from liquid sweet cheese whey, particularly suited to large-scale industrial production. This procedure includes acidification and heating and ultrafiltration of cheese whey to give a CMP powder with a protein content from 75 to 79%. CMP obtained from WPC and from pure bovine, ovine, and caprine cheese whey were characterized. The CMP recovery was close to 71-76% and the purity determined by RP-HPLC ranged from 75 to 90%.     

Effect of pH and heat treatment of cheese whey on solubility and emulsifying properties of whey protein concentrate produced by ultrafiltration

The effects of pH and heat treatment of cheese whey on protein solubility (PS) at pH 4.6 and on emulsifying properties of whey protein concentrate (WPC) were studied by response surface methodology (RSM). PS followed a quadratic relationship with pH and a linear relationship with heat treatment. Highest values for PS were found between pH 6.0 and 6.6 with heat treatment at 68 °C for 2 min, and maximum solubility was reached at pH 6.3. Heat treatment strongly decreased protein solubility throughout the entire pH range. The emulsifying properties were notably benefited by raising the pH from 6 to 7, best values being shown at pH 7 with a heat treatment of 70 °C for 2 min. The effect of heat treatment on the emulsifying properties was dependent on the pH level. At about pH 7, the heat treatment adversely affected the emulsifying properties, probably due to excessive protein denaturation.     

低脂乳的不同热处理工艺对切达奶酪品质的影响

通过对切达奶酪p H、水分含量、产率、质构和融化性的测定,研究了低脂乳的不同热处理工艺对其品质的影响。结果表明:3个不同热处理工艺下乳清蛋白变性率分别为17.5%、35.1%和68.3%。随着热处理强度的增大,切达奶酪的p H和融化性下降,水分含量和产率提高,质构指标中的硬度、弹性、内聚性和咀嚼度下降,黏着性上升。利用扫描电镜和电泳技术分析不同热处理工艺对奶酪品质造成的差异。结果表明:随着热处理强度的增大,乳清蛋白变性率增大,形成的大分子聚合物被截留在奶酪的网状结构中,影响了酪蛋白的聚集,进而对其品质产成了影响。      

High pressure treatment decelerates the lipolysis in a caprine cheese

Garrotxa cheese, a cheese made of goat's milk, typical of the Catalonian region, has been high pressure-treated (400 MPa, 5 min, 14 °C) to accelerate the ripening. The volatile fraction of Garrotxa cheese was studied on treated and untreated samples at two ripening stages by SDE extraction with dichloromethane, and identified with GC–MS. Pressure treatment at 400 MPa for 5 min decelerated the lipolysis, having treated cheese lower amount of free fatty acids, and, in general, less volatile compounds showing a tendency to decrease differences during ripening. No new volatile compounds could be identified after pressure treatment. Humidity and content of non-casein nitrogen and non-protein were higher on pressurised cheese, but bacterial counts were significantly reduced after pressure treatment. High pressure-treated Garrotxa cheese was not substantially equivalent to the regular-ripened cheese, however the treatment presented in this paper could lead to new varieties of cheese.     

Preparation of angiotensin-I-converting enzyme inhibitory hydrolysates from unsupplemented caprine whey fermentation by various cheese microflora

Unsupplemented caprine whey was fermented by 25 cheese microflora in order to produce peptides from α-lactalbumin (α-la) and/or β-lactoglobulin (β-lg) hydrolysis. Fourteen hydrolysates enriched in peptides mainly released from α-la were obtained. Angiotensin-I-converting enzyme (ACE) inhibitory activity of each hydrolysate was investigated. Six of them had high ACE inhibitory activities ranging from 31% to 56%. The highest ACE inhibitory activity was obtained after whey fermentation by the microflora from 18 months ripened Comté cheese. The microflora was identified as a co-culture of Candida parapsilosis and Lactobacillus paracasei. Hydrolysate activity remained stable after pepsin, trypsin and chymotrypsin treatments simulating an in vitro gastrointestinal digestion. This hydrolysate was further fractionated by RP-HPLC. The peptide exhibiting the highest ACE inhibitory activity was characterised as WLAHK (α-la f(104–108): Trp–Leu–Ala–His–Lys). WLAHK was resistant toward pepsin and trypsin treatments but was digested by chymotrypsin.     

Transfer of oxytetracycline from ovine spiked milk to whey and cheese

Cheese-making trials with ovine milk spiked with oxytetracycline (OTC) at maximum residue limit (MRL) level were performed to study the OTC distribution between whey and cheese, and assess its effect in cheese-making process and cheese composition. An in-house validated method, based on liquid chromatography-tandem mass spectrometry, was adopted to detect OTC in milk, whey and cheeses. The MRL OTC spike induced a delay in the pH lowering causing a higher moisture content in 1-day OTC cheese compared with the control cheese. No effects of OTC were observed on the mass balance of the process, on the recovery of fat and protein and, in general, on physico-chemical parameters and gross composition of obtained cheeses. OTC was mainly recovered in the 1-day cheeses (61 ± 5%). Despite a 17 ± 8% OTC reduction observed during cheese ripening, probably due to partial degradation, remaining residues were not negligible and could contribute to reach the acceptable daily intake.     

Permeate from cheese whey ultrafiltration is a source of milk oligosaccharides

Previously undescribed oligosaccharides in bovine cheese whey permeate were characterized by a combination of nanoelectrospray Fourier transform ion cyclotron resonance (nESI-FTICR) mass spectrometry and matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance (MALDI-FTICR) mass spectrometry. Oligosaccharide composition was elucidated by collision-induced dissociation within the ICR cell. In addition to sialyllactose (the most abundant oligosaccharide in bovine colostrum), we identified 14 other oligosaccharides, half of which have the same composition of human milk oligosaccharides. These oligosaccharides could potentially be used as additives in infant formula and products for the pharmaceutical industry. Because whey permeate is a by-product from the production of whey protein concentrate (WPC) and is readily available, it is an attractive source of oligosaccharides for potential application in human nutrition.     

Effects of protein and fat levels in milk on cheese and whey compositions

Bulk tank milk was standardised to six levels of fat (3·0, 3·2, 3·4, 3·6, 3·8, 4·0%) and similarly to six levels of protein, thus giving a total of 36 combinations in composition. Milk was analyzed for total solids, fat, protein, casein, lactose and somatic cell count and was used to make laboratory-scale cheese. Cheese samples from each batch were assayed for total solids, fat, protein and salt. Losses of milk components in the whey were also determined. Least squares analysis of data indicated that higher protein level in milk was associated with higher protein and lower fat contents in cheese. This was accompanied by lower total solids (higher moisture) in cheese. Inversely, higher fat level in milk gave higher fat and lower protein and moisture contents in cheese. Higher fat level in milk resulted in lower retention of fat in cheese and more fat losses in the whey. Higher protein level in milk gave higher fat retention in cheese and less fat losses in the whey. Regression analysis showed that cheese fat increased by 4·22%, while cheese protein decreased by 2·61% for every percentage increase in milk fat. Cheese protein increased by 2·35%, while cheese fat decreased by 6·14% per percentage increase in milk protein. Milk with protein to fat ratio close to 0·9 would produce a minimum of 50% fat in the dry matter of cheese.     

The effect of protein profile and preheating on denaturation of whey proteins and development of viscosity in milk protein beverages during heat treatment

The effect of preheat temperature (63 or 77 °C for 30 s; final heat 120 °C for 30 s) and casein to whey protein ratio on the physical characteristics of 3.3%, w/w, dairy protein beverages was investigated. Dispersions preheated at 77 °C had lower viscosity than dispersions preheated at 63 °C. Casein‐containing dispersions had significantly lower levels of α‐lactalbumin denaturation than whey protein‐only dispersions. A higher proportion of casein improved the thermal stability of protein dispersions. Overall, alteration of preheat temperature and casein to whey protein ratio can influence dairy beverage quality, with increasing levels of casein reducing physical changes due to heat treatment.     

Evolution and distribution of phospholipids in cheese and whey during the manufacturing of fresh cheese from cows' milk

In this study, we report on the evolution of phospholipid contents and their distribution in cheese and whey, during the production of fresh cheese. We found that the phospholipid content in the total mass of whey and fresh cheese together was greater than the content of phospholipids in the starting milk used to make them. This increase was probably due to bacterial growth during fermentation and the consequent synthesis of phospholipids to generate cell membranes. In the coagulation process, ≈20% of the phospholipids were drained in the whey. Based on this result, we conclude that whey might be an interesting source of phospholipids, mainly phosphatidylethanolamine and sphingomyelin, for the food industry.