Lipolysis,proteolysis and sensory properties of ewe’s raw milk cheese (Idiazabal) made with lipase addition

In this paper, we describe the effect of the addition of pregastric lipase on the composition and sensory properties of Idiazabal cheese. Free fatty acids (FFA), partial glycerides, free amino acids (FAA), gross composition and sensory characteristics were determined at different ripening times in cheeses manufactured with three different amounts of commercial animal lipase or with lipase-containing artisanal lamb rennet paste. The addition of lipase increased the content of total FFA, particularly of short-chain FFA, and that of total partial glycerides in cheeses. Unexpectedly, lipase utilization significantly affected total FAA concentration, which decreased in cheeses elaborated with high lipase amount. In general, Val, Glu and Leu were the major FAA, and their concentrations depended, mainly, on ripening time. Lipase addition had significant influence on the sensory characteristics of the cheeses, increasing scores for most of the flavour and odour attributes of the cheese. Principal component analysis (PCA) was done including dry matter, FFA, FAA, partial glycerides and odour and flavour attributes of the cheeses. It indicated that aroma and flavour parameters of Idiazabal cheese and the content of short-chain FFA and diglycerides were highly correlated to first principal component (PC1), while texture parameters, compositional variables and FAA were correlated to the second principal component (PC2).     

Free fatty acid composition of regionally-produced Spanish goat cheese and relationship with sensory characteristics

A study was made of free fatty acid composition and sensory characteristics (odour and taste) in regionally-produced Spanish goat cheeses. The most abundant FFAs were oleic, palmitic, stearic, capric and myristic acid which together accounted for roughly 85% of total FFAs. These cheeses generally underwent a lower degree of lipolysis than did other goat cheeses. Panellists judged the cheeses as having considerable odour and flavour intensity. However, both total FFA content and sensory attributes varied considerably among cheeses due, in all likelihood, to differences in ripening time and to production by different manufacturers. Principal component analysis generated three principal components (PC) that accounted for 70% of total variance; the variables that best correlated with them were long-chain and medium-chain free fatty acids (PC1), brine odour, bitterness and goat milk odour (PC2) and short-chain free fatty acids (PC3).     

Comparison of the volatile composition and sensory characteristics of Spanish PDO cheeses manufactured from ewes’ raw milk and animal rennet

Idiazabal, Manchego, Roncal and Zamorano varieties are the Spanish cheeses manufactured under Protected Denomination of Origin (PDO) from ewes’ raw milk and coagulated with animal rennet. Two batches of each cheese variety were ripened for six months and the cheeses were compared for sensory characteristics and composition of volatile compounds. Seventy-six volatile compounds were identified by GC-MS analysis of headspaces of the cheeses. The volatile profile of the four PDO cheeses differed significantly. Acids were the most abundant volatile compounds in Idiazabal, Roncal, and Zamorano cheeses, whereas alcohols were the main volatile compounds in Manchego cheese due to the large percentage of 2-butanol. Aldehydes, ketones and esters were minor compounds in all the cheese varieties, whereas terpenes and unsaturated hydrocarbons were only found in Manchego cheese. The sensory profiles, of the four PDO cheeses also differed significantly. The highest scores for sharp, brine and rennet odours, and rancid and rennet flavours were assessed in Idiazabal and Zamorano cheeses, whereas milky and buttery odour scores were higher in Manchego, Roncal and Zamorano cheeses than in Idiazabal cheese. Principal component analysis was applied to sensory attributes and volatile composition of the cheeses. Differences in flavour and odour attributes were correlated with differences in the volatile compounds. Two principal components correlating sensory attributes and volatile compounds were defined as “strength factor” and “sweetness factor”. The “strength factor” distinguished among the four cheese varieties, except between Roncal and Manchego cheeses, and the “sweetness factor” distinguished the Zamorano cheese from the Idiazabal, Manchego and Roncal cheeses.     

Relationships between the gross,non-volatile and volatile compositions and the sensory attributes of eight hard-type cheeses

Relationships between individual flavour attributes of eight hard-type cheeses and their volatile compounds, free amino acids (FAA), free fatty acids (FFA) and gross compositional constituents were determined. Relationships were also determined between individual texture attributes and gross compositional constituents. A trained panel of 15 assessors described the sensory characteristics of the cheeses using eight odour, twenty flavour, four appearance and nine texture attributes. Volatile compounds were isolated using a model-mouth device. FAA, FFA and gross compositional constituents were determined using standard methods. Relationships were determined by using partial least squares regression coupled with a new jack-knife method for identification and elimination of non-contributing variables. Eight flavour attributes were found to be correlated with subsets of volatile compounds, FAA, FFA and gross compositional constituents. For instance, the “nutty” flavour of Emmental was found to be positively correlated with the concentrations of propionic acid, ethyl acetate and 2-pentanone. “Nutty” flavour was negatively correlated with the concentrations of salt in moisture and pH 4.6-soluble nitrogen (pH 4.6-SN). Four texture attributes were correlated with subsets of gross compositional constituents. For example, “firmness” was positively correlated with concentrations of protein, calcium and phosphorous and negatively correlated with pH value and level of pH 4.6-SN.     

Effect of partial substitution of caprine milk for ovine milk,dry salting and cured scalding on lipolysis in Urfa cheeses

The objectives of this study were to determine the effect of partial substitution of caprine for ovine milk, dry salting and curd scalding on the free fatty acid (FFA) level of Urfa cheeses. At the end of storage, lauric and linoleic acids were lower in cheese made from milk where up to the 30% partial substitution of caprine milk for ovine milk was made. Dry salted cheeses had higher butyric, lauric, linoleic and linolenic acid levels, and lower palmitic acid levels than their scalded counterpart. A relative increase in short‐chain FFAs occurred during ripening. Palmitic and oleic acids were the most abundant FFAs in fresh and ripened Urfa cheeses.     

Probiotic white cheese with Lactobacillus acidophilus

The objective of the present study was to determine the effects of Lactobacillus acidophilus on the sensory attributes, ripening time, and composition of Turkish white cheese and to investigate the survival of L. acidophilus during ripening of the cheese stored in vacuum or in brine. Two types of white cheeses, traditional cheese (control, made with Lactococcus lactis ssp. lactis and Lactococcus lactis ssp. cremoris) and probiotic cheese (made with Lactococcus lactis ssp. lactis, Lactococcus lactis ssp. cremoris and L. acidophilus 593 N), were produced and ripened in vacuum pack or in brine at 4°C for 90 days. Cheese samples were assessed for microbiological and compositional properties, proteolysis, and sensory evaluation at different ripening stages. On ripening in vacuum pack, L. acidophilus survived to numbers >10⁷ cfu g⁻¹, which is necessary for positive effects on health. Protein, dry matter, salt content, and percentage of lactic acid in the vacuum-packed and brine-salted probiotic cheeses were significantly different. Also, the lactic acid content of probiotic cheeses was slightly higher than that of the controls for both vacuum- and brine-packed cheeses. Vacuum-packed probiotic cheese had the highest levels of proteolysis and the highest sensory scores of all cheeses. Consequently, L. acidophilus could be used for the manufacturing of probiotic white cheese to shorten ripening time and vacuum packaging is the preferred storage format.     

Relationships between sensory attributes and the volatile compounds,non-volatile and gross compositional constituents of six blue-type cheeses

Relationships between odour and flavour attributes of six blue-type cheeses and their volatile compounds, free amino acids (FAA), free fatty acids (FFA) and gross compositional constituents were determined. Relationships were also determined between texture attributes and gross compositional constituents. Fifteen assessors described the odour, flavour, appearance and texture profile of cheeses. Volatile compounds were isolated using a model-mouth apparatus. FAA, FFA and gross compositional constituents were determined using standard methods. Using Partial Least Squares Regression two odour and five flavour attributes were found to correlate with subsets of volatile compounds, FAA, FFA and gross compositional constituents. For example, “mouldy” flavour was positively correlated with the concentrations of pH 4.6-soluble nitrogen and 2-pentanone, 2-heptanone, 2-octanone and 2-nonanone. Three texture attributes were found to correlate with subsets of gross compositional constituents. For example, “crumbly” texture was positively correlated with concentration of fat and protein and negatively correlated with levels of moisture in the non-fat substance and moisture.     

Differences in volatiles,and chemical,microbial and sensory characteristics between artisanal and industrial Piacentinu Ennese cheeses

Piacentinu is a traditional Sicilian ewes’ milk cheese produced in the province of Enna. The objective of this study was to determine whether altering the traditional conditions under which Piacentinu cheeses are made affects their volatile organic compounds (VOCs) and sensory characteristics. Cheeses were obtained from different farms and ripened for 2 to 6 months. Those made from raw milk and artisanal rennets contained a more diverse group of VOCs, especially with respect to terpenes, and had significantly stronger aroma intensities in most categories except fruity. Cheeses made from pasteurised milk with commercial starters and rennets had significantly stronger salty and spicy tastes. Principal components analysis of the VOC and sensory data separated the two types of cheeses by their VOC “fingerprints” and a few aroma sensory attributes. Ripening time was accounted for by aroma intensity, and taste and texture attributes.     

Changes in lipid fractions and sensory properties of Idiazabal cheese induced by lipase addition

This work studied the addition of an adequate lipase to enhance lipolysis reactions and the development of piquant flavour and sharp odour in Idiazabal cheese, as an alternative to the use of lamb rennet paste. Cheeses were manufactured from bulk raw ewes' milk in 50 l vats with commercial bovine rennet and 80 lipase units of pregastric or 180 lipase units of fungal lipase and ripened for 180 days. A higher lipolytic activity was induced by lipase addition promoting strong changes in odour and flavour attributes. Both fungal and pregastric lipases increased the content of total free fatty acids (FFA), but the fungal lipase released mainly medium- and long-chain FFA. In contrast, the pregastric lipase preferably released short-chain FFA. Diglyceride (DG) content was considerably higher in cheeses made with added pregastric lipase compared with those made with fungal lipase or with no lipase. Monoglycerides (MG) were detected only in cheeses made with either lipase added, reaching comparable concentrations after ripening for 180 days. The cheeses made with pregastric lipase had the highest scores for odour and flavour intensity, and sharp and rennet odours, desirable attributes for the Idiazabal cheese made with lamb rennet paste. None of the texture attributes were significantly influenced by the concentrations of MG and DG in the cheeses made with either lipase. Thus, the pregastric lipase was more appropriate than the fungal lipase to develop a more traditionally-flavoured Idiazabal cheese.     

Changes of composition and free fatty acid contents of Urfa cheeses (a white-brined Turkish cheese) during ripening: Effects of heat treatments and starter cultures

The influences of heat treatments (at 65 °C for 20 min or 72 °C for 5 min) applied to the milk and addition of mesophilic or thermophilic starter cultures, prior to cheese-making, on the composition and free fatty acid contents of Urfa cheeses were evaluated throughout the ripening period. Sensory evaluation of cheese samples was also performed on 90th day. The basic composition of ripened cheese samples was not significantly affected by the heat treatments and starter cultures. Heat treatments adversely affected the lipolysis and sensory properties of Urfa cheeses, particularly at 72 °C. The FFA contents of cheeses made from mesophilic and thermophilic cultures were similar. Cheese made from raw milk had a higher level of lipolysis than the cheeses made from milk inoculated with mesophilic or thermophilic lactic starters (p < 0.05).     

Functionality and physico-chemical characteristics of bovine and caprine mozzarella cheeses during refrigerated storage

Low moisture part-skim Mozzarella cheeses (MC) were manufactured using fresh bovine and caprine milk to study melting, physico-chemical, textural, and microstructural properties of the cheeses during 8 wk of refrigerated storage. Structural changes in cheese matrix were evaluated by scanning electron microscopy and by proteolytic patterns using nitrogen solubility, SDS-PAGE, and Gel-pro analyzer. Meltability of ripened cow and goat MC were not different when fat content of both milks were standardized, whereas bovine MC formed a significantly larger amount of free oil throughout the experiment. The results of the proteolytic patterns, texture attribute (cohesiveness), and microstructure revealed that bovine MC had a greater structural degradation of cheese matrix than caprine MC during the storage. Elevated protein degradation in bovine MC led to more intense brown color formation than the goat counterpart when the cheeses were baked. The melting characteristics showed high positive correlation (r = 0.51 to 0.80) with proteolysis, whereas it was negatively correlated with textural characteristics. Among textural attributes, cohesiveness was highly inversely correlated with melting characteristics (r = -0.69 to -0.88). High negative correlations were also observed between proteolytic parameters and textural attributes (r = -0.48 to -0.81).     

TEXTURE EVALUATION OF FRENCH ACID-TYPE FRESH CHEESES

A range of French acid-type fresh cheeses of various commercial brands was tested by a trained sensory panel which detected significant differences in thickness, smoothness and slipperiness. The cheeses exhibited thixotropic behaviour. The perceived thickness of the samples was highly correlated with the shear stress values obtained for a limited range of shear rates (30–80 _S⁻¹). The area of the hysteresis loop formed during the first shearing cycle of the samples over a wide range of shear rates (4.5–450 _S⁻¹) was negatively correlated to slipperiness. The correlation matrix showed that the sensory attributes were independent of the chemical composition of the products. Principal components analysis indicated the way the three sensory attributes were related to each other and to the rheological parameters.     

Influence of composition on the biochemical and sensory characteristics of commercial Cheddar cheese of variable quality and fat content

Ten commercial Cheddar cheeses of variable quality differing in fat content and age were subjected to compositional, proteolytic, lipolytic and sensory analyses. The compositional parameters of the full-fat cheeses were predominantly outside those typically associated with good-quality cheese. Sensory analysis discriminated the full-fat cheeses predominantly by age, with the longer ripened cheeses associated with more negative attributes, some which appeared to be due to excessive lipolysis and/or β-casein breakdown. Both proteolysis and lipolysis appear to be age dependent. The two reduced-fat cheeses were clearly discriminated from the eight full-fat cheeses by sensory analysis that appeared to be due to differences in composition and the extent of lipolysis.     

TEXTURE ANALYSIS OF CHEDDAR CHEESE MADE FROM ULTRAFILTERED MILK

The textural properties of Cheddar cheese made from ultrafiltered milk were assessed. Cheddar cheeses were prepared from 1.5- and 2.0-fold concentrated milk and ripened for three months. Textural characteristics of the UF cheeses were compared to control and commercial Cheddar cheeses by sensory and instrumental measures. The texture of cheese made from UF milk differed from the control commercial Cheddar cheeses. According to the trained sensory panel, the UF cheeses were harder and more rubbery, crumbly, chewy and grainy than the control and commercial Cheddar cheeses (P <0.01). The texture profile analysis (TPA), conducted using the Instron, did not correspond to the sensory measurements nor was it successful in discriminating among the cheese samples. Lack of agreement between the sensory and instrumental tests was attributed to differences in the testing conditions and procedures of the two methods. Instrumental tests should be validated against sensory measures in order to be useful as measures of palatability. Consumer preferences for the commercial, control and UF Cheddar cheeses were significantly different (P < 0.01), the UF cheeses being less preferred in terms of flavor, texture and overall acceptability.     

Characterization and Comparison of Free Fatty Acid Profiles of Eleven Varieties of Turkish Cheeses

Free fatty acids profiles of 11 different cheese varieties sold in Turkey were determined to assess the development of lipolysis. Results obtained showed that the concentrations of short chain fatty acids (C₄ and C₆ free fatty acids) were close in all cheeses (P > 0.05), except for Canak cheese. However, significant differences were noted among the samples for other free fatty acids including C₈ to C_18:2 (P < 0.05). Palmitic (C₁₆) and oleic (C_18:1) acids were the most abundant free fatty acids in all cheese samples. Principal component analysis was applied to simplify interpretation of the data and distinguish the variety of the cheeses on the plot. Canak cheese gave a dramatically different free fatty acid profile from the other cheeses, probably because of the fact that ripening of this variety is achieved in the earthenware pots for about 1 year. Van Otlu (ripened with special herbs) and Civil (ripened by spontaneously molding on its surface) cheeses differed from the others by ANOVA and principal component analysis techniques. In conclusion, the degree of lipolysis in the cheeses could be classified into extreme (Canak), high (Civil, Divle Tulum, Mihalic, and Van Otlu), mild (Ezine, Orgu, and Urfa), and low (Dil, Hellim, and Malatya) based on their FFA profiles.     

Survey of the furosine content in cheeses marketed in Spain

The furosine content in 53 samples of different cheese types (fresh, ripened with molds, artisanal hard-pressed, industrial hard-pressed, and processed) marketed in Spain was analyzed. The lowest furosine values were observed in artisanal hard-pressed cheeses (4.8 to 10.2 mg per 100 g of protein) and ripened with molds cheeses (4.2 to 12.8 mg per 100 g of protein). Industrial hard-pressed cheeses showed furosine values between 3.5 and 43.8 mg per 100 g of protein. Differences between samples may be attributed to the heat-treatment intensity given to cheese milk and to cheesemaking conditions. The highest contents of furosine were observed in processed cheeses (20 to 366.6 mg per 100 g of protein). A wide range of furosine content was found in fresh cheeses (17.9 to 73.6 mg per 100 g of protein), which could be due to the different amounts of dried milk added during the manufacture of cheeses.     

Effect of ripening temperature on the growth and significance of non-starter lactic acid bacteria in Cheddar cheese made from raw or pasteurised milk

Two cheese-making trials were conducted, each involving four cheeses, two made from raw milk (R1, R8) and two from pasteurised milk (P1, P8), and ripened at 1°C (R1, P1) or 8°C (R8, P8). The 1-day-old R1 and R8 cheese in trials 1 and 2 contained ∼10⁴ non-starter lactic acid bacteria (NSLAB) g⁻¹. In trial 1, no NSLAB were detected in 1-day-old P1 and P8 cheeses while those in trial 2 contained 10² cfu g⁻¹. In both trials, the maximum differences between the number of NSLAB in the cheeses ripened at 1 or 8°C were observed at 4 months, when the number of NSLAB in cheeses ripened at 8°C were 3 log cycles higher than in those ripened at 1°C. At the end of ripening (6-months), the number of NSLAB in P8 and R8 were ∼2 log cycles higher than in P1 and R1 cheeses, respectively. Primary proteolysis in the cheeses was markedly affected by ripening temperature, but not by pasteurisation of the cheese milk. Urea-polyacyrlamide gel electrophoretograms and reverse-phase (RP)-HPLC of the water-soluble fraction showed differences between cheeses made from raw or pasteurised milk and between cheeses ripened at 1 or 8°C. The concentration of amino acids and fatty acids were in the order R8>P8>R1>P1. Commercial graders awarded highest flavour scores to the R1 cheeses during gradings at 4, 5 and 6 months. A sensory panel found that most flavour and aroma attributes and maturity were in the order of R8>P8>R1=P1. The results of this study suggest that NSLAB play an important role in the development of flavour in Cheddar cheese by contributing to the production of amino acids and fatty acids.     

Effects of Commercial Food Grade Enzymes on Free Fatty Acid Profiles in Granular Cheddar Cheese

Commercial food grade enzymes (Neutrase, calf lipase and NaturAge) were incorporated into cheese at various concentrations and ripened at 7° and 13°C. Gas chromatographic analysis indicated that free fatty acid (FFA) production increased significantly (p<0.05) with lipase and high level NaturAge. Neutrase had little effect on FFA production but showed synergistic effects with lipase. The short-chain FFA profiles were similar among control, Neutrase- and NaturAge-treated cheeses. Significant correlations (p<0.05) between C₈ and C₁₄, C₁₆ or C_18:1 and total free fatty acids were observed in all tested samples. Total concentrations of C₄ and C₆ may be a good indicator of flavor development during cheese ripening. Cheese with a medium level of NaturAge, ripened at 13°C for 4 wk, showed profiles of FFA similar to those of the control cheese ripened at 7°C for 12 wk.