Influence of calcium and phosphorus, lactose, and salt-to-moisture ratio on Cheddar cheese quality: changes in residual sugars and water-soluble organic acids during ripening

Cheddar cheese ripening involves the conversion of lactose to glucose and galactose or galactose-6-phosphate by starter and nonstarter lactic acid bacteria. Under ideal conditions (i.e., where bacteria grow under no stress of pH, water activity, and salt), these sugars are mainly converted to lactic acid. However, during ripening of cheese, survival and growth of bacteria occurs under the stressed condition of low pH, low water activity, and high salt content. This forces bacteria to use alternate biochemical pathways resulting in production of other organic acids. The objective of this study was to determine if the level and type of organic acids produced during ripening was influenced by calcium (Ca) and phosphorus (P), residual lactose, and salt-to-moisture ratio (S/M) of cheese. Eight cheeses with 2 levels of Ca and P (0.67 and 0.47% vs. 0.53 and 0.39%, respectively), lactose at pressing (2.4 vs. 0.78%), and S/M (6.4 vs. 4.8%) were manufactured. The cheeses were analyzed for organic acids (citric, orotic, pyruvic, lactic, formic, uric, acetic, propanoic, and butyric acids) and residual sugars (lactose, galactose) during 48 wk of ripening using an HPLC-based method. Different factors influenced changes in concentration of residual sugars and organic acids during ripening and are discussed in detail. Our results indicated that the largest decrease in lactose and the largest increase in lactic acid occurred between salting and d 1 of ripening. It was interesting to observe that although the lactose content in cheese was influenced by several factors (Ca and P, residual lactose, and S/M), the concentration of lactic acid was influenced only by S/M. More lactic acid was produced in low S/M treatments compared with high S/M treatments. Although surprising for Cheddar cheese, a substantial amount (0.2 to 0.4%) of galactose was observed throughout ripening in all treatments. Minor changes in the levels of citric, uric, butyric, and propanoic acids were observed during early ripening, whereas during later ripening, a substantial increase was observed. A gradual decrease in orotic acid and a gradual increase in pyruvic acid content of the cheeses were observed during 12 mo of ripening. In contrast, acetic acid did not show a particular trend, indicating its role as an intermediate in a biochemical pathway, rather than a final product.     

Influence of ripening on proteolysis and lipolysis of Murcia al Vino cheese

The aim of this study was to evaluate the influence of five different manufacturers and two ripening periods on the proteolysis and lipolysis patterns of Murcia al Vino goat cheese. The manufacturers significantly affected the water activity (a_w), pH, dry matter and fat content, several nitrogen fractions: water soluble nitrogen (WSN), trichloroacetic acid (12% w/v) soluble nitrogen (TCASN) and phosphotungstic acid (5% w/v) soluble nitrogen (PTASN); also the free amino acid (FAA) and free fatty acid (FFA) contents, with the exception of C_4:0, C_16:0 and C_18:0. Different ripening periods significantly affected the dry matter content, WSN and PTASN and all FAA, except serine.     

驼乳干酪的工艺优化及成熟期间的理化特性

研究了驼乳干酪最佳加工工艺及成熟期间理化和微生物指标的变化。确定了驼乳干酪的最佳工艺参数:发酵剂的添加量为0.006%,CaC12的添加量为0.03 g/L,pH值为6.1,凝乳酶的添加量为0.06 g/L,凝乳温度为35℃。驼乳干酪的干物质质量分数约为45%,随成熟时间的延长,驼乳干酪的蛋白质、脂肪、乳糖、水分,质量分数下降;硬度、咀嚼性升高,但黏着性和弹性降低;pH4.6-SN的质量分数、12%TCA-SN和5%PTA-SN的质量分数都有不同程度的上升;发酵剂乳酸菌数在逐渐降低,非发酵剂活菌数却在逐渐增高。     

Effect of a commercial adjunct culture on organic acid contents of low-fat Feta-type cheese

The effect of a commercial adjunct culture (CR-213, containing Lactococcus lactis subsp. cremoris and Lactococcus lactis susp. lactis and added at the level of 0.6 g kg⁻¹ or 0.9 g kg⁻¹ cheese milk) on the organic acid (OA) content of low-fat Feta-type cheese was studied. Full-fat (∼220 g kg⁻¹) and a low-fat (∼70 g kg⁻¹) cheeses were used as controls. The main OA of all cheeses throughout ripening were lactic, citric and acetic acids. The effect of ripening time was significant (P < 0.05) for all OA but treatments did not affect acetic, succinic and uric acids. Cheeses with lower fat content were found to contain significantly (P < 0.05) more lactic and citric but less butyric acid than the full-fat control. The addition of the adjunct culture had a positive effect on butyric acid, propionic acid and acetoin content. The use of the adjunct culture could enhance the production of OA in low-fat Feta-type cheeses with eventual positive effect on their sensory properties.     

Influence of animal and vegetable rennet on the physicochemical characteristics of Los Pedroches cheese during ripening

The effects of rennet type (animal or vegetable) on the physicochemical characteristics (moisture, fat, protein, lactose, lactic acid, NaCl, ash, water activity, pH and nitrogen fractions: SN, NPN, AAN and NH₃-N) of “Los Pedroches” cheese manufactured with pure ewes' milk were investigated. Changes were observed during 100 days of ripening. Analysis of the covariance was carried out, using these chemical composition data, expressed as a function of the dry matter. The rennet type influenced moisture, protein, and water activity values (higher in the cheeses manufactured with animal rennet), fat and SN (higher in cheeses manufactured with vegetable rennet). There was a significant rising trend in the levels of lactic acid, ash, NaCl, and nitrogen fractions during ripening, while a significant decrease was observed in the moisture, lactose, pH and a_w values.     

Changes in organic acids during ripening of cheeses made from raw, pasteurized or high-pressure-treated goats’ milk

Organic acids of cheeses made from raw (RA), pasteurized (PA; 72°C, 15 s) or pressure-treated (PR; 500 MPa, 15 min, 20°C) goats’ milk were qualitatively and quantitatively assessed during ripening. Nine organic acids (citric, pyruvic, malic, lactic, formic, acetic, uric, propionic and butyric) were analysed in each sample by HPLC.Milk treatment did not affect the total organic acids content of 1-day-old cheeses, which increased steadily from day 1 to day 60. At the end of ripening, RA and PR milk cheeses both exhibited higher concentration of organic acids than in those made from PA milk.Lactic acid was found in higher concentration in PR milk cheese from 30 days of ripening. The RA milk cheese, that showed the highest nonstarter lactic acid bacteria counts, were characterized by an elevated amount of propionic and acetic acids. These cheeses also were negatively correlated with both pyruvic and citric acid contents. The PA milk cheese showed a high level of malic acid, and was clearly differentiate from RA and PR milk cheeses by its low level of butyric acid.     

Changes of Mineral Concentrations in Serra Cheese during Ripening and Throughout the Cheesemaking Season

Seasonal changes of the ash content and mineral concentrations in Serra cheese were studied over a typical 35-day ripening period. Statistically significant differences (at the 5% level) exist between the ash content and the concentrations of Na, K, Ca, P, Mg and Zn in cheeses during ripening. The highest concentrations of Na was obtained in cheese ripened for 7 days, whereas the concentrations of K, Ca, P, Ng and Zn decreased significantly during ripening. For 35-day-old cheeses, concentrations of Na, K and Cu were lowest and concentration of P was highest for cheeses manufactured in May. The concentration of Ca was lowest for cheeses manufactured in February. On average, the most concentrated minerals (in g kg^-1 of total solids, TS) in 35-day-old Serra cheese were Na (18·56), Ca (9·70) and P (7·92) and, at a lower level, K (1·70) and Mg (0·96). Only trace levels (in mg kg_TS^-1) of Zn (94·33), Cu (2·26) and Mn (1·25) were detected. A high mineral nutrition quality was thus ascribed to 35-day-old Serra cheese based on the average nutritional densities: 4·8 for Ca, 4·0 for P, 1·1 for Mg, 3·4 for Na, 2·4 for Zn, 0·4 for Cu, 0·2 for Mn and 0·2 for K. © 1997 SCI     

Effect of different curd-washing methods on the insoluble Ca content and rheological properties of Colby cheese during ripening

A curd-washing step is used in the manufacture of Colby cheese to decrease the residual lactose content and, thereby, decrease the potential formation of excessive levels of lactic acid. The objective of this study was to investigate the effect of different washing methods on the Ca equilibrium and rheological properties of Colby cheese. Four different methods of curd-washing were performed. One method was batch washing (BW), where cold water (10°C) was added to the vat, with and without stirring, where curds were in contact with cold water for 5 min. The other method used was continuous washing (CW), with or without stirring, where curds were rinsed with continuously running cold water for approximately 7 min and water was allowed to drain immediately. Both methods used a similar volume of water. The manufacturing pH values were similar in all 4 treatments. The insoluble (INSOL) Ca content of cheese was measured by juice and acid-base titration methods and the rheological properties were measured by small amplitude oscillatory rheology. The levels of lactose in cheese at 1 d were significantly higher in CW cheese (0.06-0.11%) than in BW cheeses (∼0.02%). The levels of lactic acid at 2 and 12 wk were significantly higher in CW cheese than in BW cheeses. No differences in the total Ca content of cheeses were found. Cheese pH increased during ripening from approximately 5.1 to approximately 5.4. A decrease in INSOL Ca content of all cheeses during ripening occurred, although a steady increase in pH took place. The initial INSOL Ca content as a percent of total Ca in cheese ranged from 75 to 78% in all cheeses. The INSOL Ca content of cheese was significantly affected by washing method. Stirring during manufacturing did not have a significant effect on the INSOL Ca content of cheese during ripening. Batch-washed cheeses had significantly higher INSOL Ca contents than did CW cheeses during the first 4 wk of ripening. The maximum loss tangent values (meltability index) of CW cheese at 1 d and 1 wk were significantly higher compared with those of BW cheeses. In conclusion, different curd washing methods have a significant effect on the levels of lactose, lactic acid, meltability, and INSOL Ca content of Colby cheese during ripening.     

Enhanced lactose cheese milk does not guarantee calcium lactate crystals in finished cheddar cheese

Three experimental batches of Cheddar cheese were manufactured in duplicate, with standardization of the initial cheese-milk lactose content to high (5.24%), normal (4.72%, control), and low lactose (3.81%). After 35 d of aging at 4.4°C, the cheeses were subjected to temperature abuse (24 h at 21°C, unopened) and contamination (24 h at 21°C, packages opened and cheeses contaminated with crystal-containing cheese). After aging for 167 d, residual cheese lactose (0.08 to 0.43%) and l(+)-lactate concentrations (1.37 to 1.60%) were high and d(−)-lactate concentrations were low (<0.03%) for all cheeses. No significant differences in lactose concentrations were attributable to temperature abuse or contamination. No significant differences in l(+)- or d(−)-lactate concentrations were attributable to temperature abuse. However, concentrations of l(+)-lactate were significantly lower and d(−)-lactate were significantly higher in contaminated cheeses than in control cheeses, indicating inoculation (at d 35) with heterofermentative nonstarter lactic acid bacteria able to racemize l(+)-lactate to d(−)-lactate. The fact that none of the cheeses exhibited crystals after 167 d demonstrates that high cheese milk or residual lactose concentrations do not guarantee crystal formation. Contamination with nonstarter lactic acid bacteria can significantly contribute to d(−)-lactate accumulation in cheese.     

Lipolysis in probiotic and synbiotic cheese: The influence of probiotic bacteria, prebiotic compounds and ripening time on free fatty acid profiles

The influence of probiotic bacteria (Lactobacillus casei-01, Bifidobacterium lactis B94), prebiotic compounds (FOS and inulin) and ripening time (0-60 days) on the free fatty acid (FFA) profile of cheese, with special emphasis on the conjugated linoleic acid (CLA) content, was investigated. After 60 days of ripening, 10⁹-10¹⁰ cfu g⁻¹ cheese were recorded in both probiotic and synbiotic cheeses, despite harsh conditions of low pH values (4.1-5.1) and low moisture content (<30%, w/w). Increases in total FFA and CLA were observed throughout the ripening period, especially in synbiotic cheeses containing FOS and inulin (50:50) inoculated with B. lactis B94. The addition of FOS alone or combined with inulin did not significantly affect probiotic strain growth and viability during the ripening period; however, the advantage of the addition of prebiotic compounds in probiotic cheese manufacture is that it may allow the production of cheeses with improved performance as far as functional CLA compounds are concerned, as well as an improved nutritional quality reflected in a lower atherogenicity index.     

Secondary proteolysis in Serra cheese during ripening and throughout the cheese-making season

 Experimental Serra cheeses were manufactured from raw ewe’s milk and thistle flowers following a two-way factorial design. The content of nitrogen soluble in water (WSN), in 2% trichloroacetic acid (2% TCA-N), in 12% TCA (TCA-N) and in 5% phosphotungstic acid (5% PTA-N), and the pH and salt-in-moisture concentration were measured throughout the ripening period (sampling at 0, 7, 21 and 35 days) and the cheese-making season (sampling in November, February and May). Proteolysis in 35-day-old Serra cheese was quantitatively high [average values of 34.6% and 11.9% for WSN/TN (total nitrogen) and 2% TCA-N/TN, respectively], but qualitatively low (average values of 5.8% and 1.2% for 12% TCA-N/TN and 5% PTA-N/TN, respectively). The ratios WSN/TN and 2% TCA-N/TN were lowest for cheeses ripened in February, whereas the ratio 12% TCA-N/TN was highest for cheeses ripened in November. By 35 days of ripening, the average pH and salt-in-moisture concentration values were 5.2 and 4.8%, respectively. No correlation was found to occur between the measured pH or salt-in-moisture concentration and the values of soluble nitrogen fractions throughout the cheese-making season. Received: 14 February 1996/Revised version: 4 June 1996     

Textural changes of Canestrello Pugliese cheese measured during storage

The changes in the fundamental textural properties of the Canestrello Pugliese cheese, during ripening, were studied, accounting for the internal and external portions of the cheese. The cheese was ripened at 12–14 °C and 80% relative humidity and analyzed at 0, 15, 30, 45, 60, 95, and 120 days to determine the moisture content, water activity (A_w), pH values and some fundamental-mechanical and dynamic-mechanical properties such as the elastic modulus (E_c), storage modulus (G′), loss modulus (G″) and relaxation times distribution curve. Significant differences in the moisture content, A_w, pH and the elastic modulus were observed for the inside and outside portions of the investigated cheese. In particular, for the first 60 days of ripening the elastic modulus of the outer region was higher than that of the inner region. As the ripening process approached the end of the fourth month the contrary was true. Moreover, results show that, above all the pH and A_w play a major role in determining the mechanical properties of the Canestrello Pugliese cheese during ripening.     

Short communication: Little change takes place in Camembert-type cheese water activities throughout ripening in terms of relative humidity and salt

Water activity (a_w) affects the growth and activity of ripening microorganisms. Moreover, it is generally accepted that a_w depends on relative humidity (RH) and salt content; these 3 variables were usually measured on a given day in a cheese without the microorganism layer and without accounting for a distinction between the rind, the underrind, and the core. However, a_w dynamics have never been thoroughly studied throughout cheese ripening. Experimental Camembert cheeses were ripened under controlled and aseptic conditions (temperature, gaseous atmosphere, and RH) for 14 d. In this study, only RH was varied. Samples were taken from the cheese (microorganism layer)–air interface, the rind, and the core. The a_w of the cheese–air interface did not change over ripening when RH varied between 91 and 92% or between 97 and 98%. However, on d 5, we observed a small but significant increase in a_w, which coincided with the beginning of growth of Penicillium camemberti mycelia. After d 3, no significant differences were found between the a_w of the cheese–air interface, the rind, and the core. From d 0 to 3, cheese rind a_w increased from 0.94 to 0.97, which was probably due to the diffusion of salt from the rind to the core: NaCl content in the rind decreased from 3.7 to 1.6% and NaCl content in the core increased from 0.0 to 1.6%. Nevertheless, a_w did not significantly vary in the core, raising questions about the real effect of salt on a_w.     

Effect of milk pasteurisation temperature on age-related changes in lactose metabolism,pH and the growth of non-starter lactic acid bacteria in half-fat Cheddar cheese

Half-fat Cheddar cheese (∼15%, w/w, fat) was manufactured on three occasions from milk pasteurised at 72, 77, 82 or 87 °C for 26 s, and analysed over a 270 day ripening period. Increasing milk pasteurisation temperature significantly increased the levels of moisture (from ∼45% at 72 °C to 50% at 87 °C), total lactate, and D(−)-lactate in cheese over the 270 day ripening period. Conversely, the cheese pH decreased significantly on increasing pasteurisation temperature. Increasing the pasteurisation temperature did not significantly affect the populations of starter or non-starter lactic acid bacteria during maturation. The use of higher pasteurisation temperatures would appear particularly amenable to exploitation as a means of producing high-moisture (e.g., 40–41%), short-ripened, mild-flavoured Cheddar or Cheddar-like cheeses.     

EFFECT OF CALCIUM AND PHOSPHORUS, RESIDUAL LACTOSE AND SALT-TO-MOISTURE RATIO ON TEXTURAL PROPERTIES OF CHEDDAR CHEESE DURING RIPENING

The texture profile analysis (TPA) parameters and meltability of Cheddar cheeses with varying levels of calcium (Ca) and phosphorus (P) content, residual lactose content and salt‐to‐moisture (S/M) ratio were studied at 0, 1, 2, 4, 6 and 8 months of ripening. The TPA hardness had an inverse relationship with the meltability of Cheddar cheese and at any given ripening time, lower TPA hardness corresponded to higher meltability of Cheddar cheese. Higher Ca and P content (0.67% Ca and 0.53% P) in Cheddar cheese resulted in up to 22.8, 5.7, 14.6, 13.5 and 35.2% increase in hardness, springiness, cohesiveness, resilience and chewiness values, respectively, and up to 23.5 and 27.7% decrease in meltability and adhesiveness values during ripening compared to the Cheddar cheese prepared with lower Ca and P content (0.53% Ca and 0.39% P). Higher residual lactose content (1.4%) in Cheddar cheese resulted in up to 24.6, 8.8 and 20.0% increase in hardness, cohesiveness and chewiness values, respectively, and up to 12.7% decrease in meltability value in the Cheddar cheese during ripening compared to the lower lactose content (0.78%). High S/M ratio (6.4) resulted in up to 29.4, 30.3 and 29.4% increase in hardness, adhesiveness and chewiness values, respectively, and up to 7.3% decrease in meltability value in Cheddar cheese compared to low S/M ratio (4.8) during ripening.     

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.     

Insoluble calcium content and rheological properties of Colby cheese during ripening

Colby cheese was made using different manufacturing conditions (i.e., varying the lactose content of milk and pH values at critical steps in the cheesemaking process) to alter the extent of acid development and the insoluble and total Ca contents of cheese. Milk was concentrated by reverse osmosis (RO) to increase the lactose content. Extent of acid development was modified by using high (HPM) and low (LPM) pH values at coagulant addition, whey drainage, and curd milling. Total Ca content was determined by atomic absorption spectroscopy, and the insoluble (INSOL) Ca content of cheese was measured by the cheese juice method. The rheological and melting properties of cheese were measured by small amplitude oscillatory rheometry and UW-Melt Profiler, respectively. There was very little change in pH during ripening even in cheese made from milk with high lactose content. The initial (d 1) cheese pH was in the range of 4.9 to 5.1. The INSOL Ca content of cheese decreased during the first 4 wk of ripening. Cheeses made with the LPM had lower INSOL Ca content during ripening compared with cheese made with HPM. There was an increase in melt and maximum loss tangent values during ripening except for LPM cheeses made with RO-concentrated milk, as this cheese had pH <4.9 and exhibited limited melt. Curd washing reduced the levels of lactic acid produced during ripening and resulted in significantly higher INSOL Ca content. The use of curd washing for cheeses made from high lactose milk prevented a large pH decrease during ripening; high rennet and draining pH values also retained more buffering constituents (i.e., INSOL Ca phosphate), which helped prevent a large pH decrease.     

非发酵剂乳酸菌A-3和D-3对半硬质山羊奶干酪成熟的影响

目的获得加速半硬质山羊奶干酪成熟的非发酵剂乳酸菌菌株(non-starterlacticacidbacteria,NSLAB)。方法以前期分离自地中海地区山羊奶干酪中的2株优良NSLAB菌株为研究对象,测定其对干酪成熟过程中组成成分、微生物菌群、蛋白质水解和质构的影响。结果添加NSLAB菌株对干酪组成成分没有显著影响, NSLAB菌株没有影响乳球菌生长,在干酪成熟期间pH 4.6-SN和12%TCA-SN逐渐增加,且添加NSLAB的干酪在成熟30 d后显著增加了pH 4.6-SN和12%TCA-SN含量, 5%PTASN/TN的增加主要是由于乳酸菌中肽酶作用的结果, SDS-PAGE电泳结果说明添加NSLAB菌株的干酪中小分子多肽含量明显比对照干酪多,RP-HPLC分析得出干酪水溶性中肽的数量随着成熟时间增加。添加NSLAB菌株A-3没有改变干酪的硬度,使干酪的弹性增加。结论添加菌株A-3作为NSLAB的干酪样品中微生物自溶率高,蛋白水解程度强,质构性能良好,具有加速干酪成熟的潜力,是山羊奶干酪工业化生产的优良NSLAB。     

Viscoelastic Properties of Cheddar Cheese: Effect of Calcium and Phosphorus,Residual Lactose,Salt-to-Moisture Ratio and Ripening Time

The viscoelastic properties of eight different types of Cheddar cheeses prepared with two levels of calcium (Ca) and Phosphorus (P) content, two levels of residual lactose content and two levels of salt to moisture ratio (S/M) ratio were studied in a STRESSTECH viscoanalyzer. The elastic (G′) and viscous (G″) modulus were measured at 0, 1, 2, 4, 6, and 8 months of ripening during heating the cheese samples from 30 to 70°C. Low levels of Ca and P content (0.53 g Ca and 0.39 g P /100 g cheese) in the Cheddar cheese resulted up to 20.9% and 15.9% lower elastic and viscous modulus respectively, compared to Cheddar cheese prepared with high levels of Ca and P content (0.67 g Ca and 0.53 g P/100g cheese) during ripening up to 8 months. Low levels of residual lactose (0.78 g/100g) in the Cheddar cheese resulted in 39.1 and 78.1% lower elastic and viscous modulus, respectively, compared to Cheddar cheese with high levels of residual lactose (1.4 g/100g) during ripening up to 8 months. In the same way, low levels of S/M ratio (4.8) in the Cheddar cheese resulted in 40.7 and 40.5% lower elastic and viscous modulus, respectively, compared to high levels of S/M ratio (6.4) during ripening up to 8 months. Upon heating from 30 to 70°C, the elastic and viscous modulus of the eight different types of Cheddar cheeses reduced up to 91.7 and 95.1%, respectively, during ripening. Cheddar cheese recorded maximum elastic modulus at the end of 8 months of ripening, and maximum viscous modulus at the end of 4 months of ripening.