Quality and ripening changes of Ras cheese made by direct acidification

Trials were carried out to produce Ras cheese of good quality without the use of starter. Cheese was made from pasteurized cow's milk acidified with lactic acid or citric acid to pH 5.8 alone or coupled with mixing the curd with glucono δ lactone (4.5 g/kg curd). Control cheese was made from milk ripened with a starter culture of S. lactis. Resultant cheeses showed poor body and texture, weak flavour intensity and low levels of soluble nitrogen compounds and free volatile fatty acids. Incorporation into the cheese curd of mixtures containing Fromase 100 (fungal protease) and Piccantase B (fungal lipase) or Fromase 100 and Capalase K (animal lipase) enhanced flavour intensity, improved body characteristics and accelerated the formation of both soluble nitrogen compounds and free volatile fatty acids. The organoleptic properties of the experimental cheeses with added enzymes were comparable to those of the control cheese.     

Influence of the starter culture on the microbiological and sensory characteristics of ewe's cheese

Changes which take place in the sensory characteristics of cheeses during ripening are influenced by different factors, involving rennet, starter culture and adventitious contamination of the cheese by non-starter lactic acid bacteria. The objective of this work was to study the influence of the starter on sensory and microbiological ewe's cheese properties during ripening time. Four batches (two with starter added and two without) were manufactured. Milk and cheeses at different stages of ripening were analysed. Cheeses manufactured without adding starter showed a significantly higher level of mesophilic aerobic microflora, lactobacilli, facultatively heterofermentative lactobacilli and enterococci (indigenous microflora) than cheeses manufactured with starter. This study has also shown that adding or not adding starter affects the flavour profile of the cheese. Cheeses with starter added showed greater intensity of the following attributes: refreshing, astringent, sweet; and received lower scores on bitterness. With respect to texture, the said cheeses develop a more homogenous texture and greater elasticity throughout ripening.     

Effect of starter cultures on the physico‐chemical and biochemical features in ewe cheese made with extracts from flowers of Cynara cardunculus L

The effect of starter cultures on the physico‐chemical and biochemical features of Los Pedroches cheese made by using Cynara Cardunculus L extracts as vegetable coagulant was assessed. Specimens of cheese containing no starter (vats A and C) and others to which a lactic acid starter was added (vats B and D) were stored either under typical farmhouse ripening conditions (vats A and B) or in a controlled chamber at 14°C and 80% relative humidity (vats C and D) for 90 days. The addition of starter cultures and the ripening conditions where found to have no appreciable effect on the moisture, fat, protein, ash, NaCl, Ca and P contents of the cheese, nor on its water activity; however, it resulted in increased lactic acid contents and lower pH values relative to control specimens throughout ripening. The protein breakdown of the cheeses was assessed in terms of soluble nitrogen, non‐protein nitrogen, aminoacid nitrogen, ammonia nitrogen, soluble tyrosine and tryptophan, and urea‐PAGE. Proteolysis was generally more marked and rapid in cheese containing the lactic starter, the NPN, NH₃ ‐N and soluble Tyr and Trp contents of which were significantly higher than those of the cheese obtained with no starter. The PAGE technique revealed no appreciable differences between the four cheese batches studied; however, it showed the cheese to be more resistant to β‐CN hydrolysis than to α_s‐CN hydrolysis. In general, the flavour and aroma scores were higher in batches obtained with starter cultures and ripened under controlled conditions. © 1999 Society of Chemical Industry     

Impact of liposome-encapsulated enzyme cocktails on cheddar cheese ripening

Cheddar cheese proteolysis and lipolysis were accelerated using liposome-encapsulated enzymatic cocktails. Flavourzyme, neutral bacterial protease, acid fungal protease and lipase (Palatase M) were individually entrapped in liposomes and added to cheese milk prior to renneting. Flavourzyme was tested alone at three concentrations (Z1, Z2 and Z3 cheeses). Enzyme cocktails consisted of lipase and bacterial protease (BP cheeses), lipase and fungal protease (FP cheeses) or lipase and Flavourzyme (ZP cheeses). The resulting cheeses were chemically, rheologically and organoleptically evaluated during 3 months of ripening at 8 °C. Levels of free fatty acids and appearance of bitter and astringent peptides were measured. Certain enzyme treatments (BP and ZP) resulted in cheeses with more mature texture and higher flavor intensity in a shorter time compared with control cheeses. No bitter defect was detected except in 90-day-old FP cheese. A full aged Cheddar flavor was developed in Z3 and ZP cheeses, while treatment BP led to strong typical Cheddar flavor by the second month and did not exhibit any off-flavor when ripening was extended for a further month.     

Compositional,biochemical and textural changes during ripening of Tulum cheese made with different coagulants

In the present study, biochemical, chemical and texture changes in Tulum cheeses made using calf rennet and microbial rennets (Aspergillus niger protease and Rhizomucor miehei protease) were compared during ripening for up to 90 days. A total of 15 free fatty acids (FFAs) were detected in the cheese samples. The peroxide values (PV) of the cheeses increased significantly (P < 0.05) during ripening and the cheese made with calf rennet had the highest PV. Proteolysis in the cheeses increased as the ripening time increased. α_s1‐casein and β‐casein degradation was higher in cheeses manufactured with R. miehei protease. Cheeses made with calf rennet were significantly (P < 0.05) harder, more adhesive, more cohesive and more resilient than those made with microbial rennet.     

Proteolysis texture and microstructure of low‐fat Tulum cheese affected by exopolysaccharide‐producing cultures during ripening

The objective of the study was to determine the effects of exopolysaccharide (EPS)‐producing or non‐EPS‐producing starters on proteolysis, physical and microstructural characteristics of full‐fat or low‐fat Tulum cheeses during ripening. For this purpose, Tulum cheese was manufactured using full‐ or low‐fat milk with EPS‐producing and non‐EPS‐producing starter cultures. Chemical composition, proteolysis, texture profiles and microstructure of the cheeses were studied during 90 days of ripening. Urea‐PAGE of water‐insoluble and RP‐HPLC peptide profiles of water‐soluble fractions of the cheeses showed that the use of starters resulted in different degradation patterns in all cheeses during ripening. Although β‐casein exhibited similar degradation patterns in all cheeses, small differences are present in α_s1‐casein degradation during ripening. Reducing fat in Tulum cheese changed the RP‐HPLC peptide profile of the cheeses. The use of EPS‐producing cultures improved the textural characteristics and changed the microstructure and proteolysis of low‐fat Tulum cheese.     

Enhancement of Blue cheese flavour using sodium dodecylsulphate and lipase

Accelerated Blue cheese ripening as affected by addition of sodium dodecylsulphate (SDS) in levels of 0.05 or 0.075% alone or SDS (0.05 or 0.075%) + lipase was studied. There were no effects on the cheese chemical composition by addition to the cheese curd of SDS or SDS/lipase combination, except for an increase in titratable acidity of cheese. Proteolysis, lipolysis and carbonyl formation were enhanced in Blue cheese treated with SDS alone. Addition of lipase with SDS greatly increased lipolysis and carbonyl formation but it did not increase proteolysis as SDS alone. Organoleptic evaluation indicated that addition of SDS alone or in combination with lipase enhanced the development of texture and flavour of cheese and improved Penicillium roqueforti distribution throughout the cheese. Cheese treated with SDS (0.075%) and lipase showed higher quality than the other cheeses.     

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.     

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).     

Casein breakdown during ripening of Idiazabal cheese: influence of starter and rennet type

The objective of this work was to determine the effect of starter and rennet type on casein breakdown during Idiazabal cheese ripening. Four batches of cheeses were manufactured with two rennets, commercial calf rennet and artisanal lamb rennet, and the use of natural flora or a commercial starter. Electrophoretic analysis of cheese samples showed six bands identified as α_s1‐, α_s2 + β‐, α_s1‐I‐, γ₁‐, β‐I‐ and para‐κ‐casein. As expected, the casein breakdown during cheese ripening was considerably affected by rennet type and the use of a commercial starter. The artisanal lamb rennet produced a higher hydrolysis of casein fractions than the commercial calf rennet, probably owing to its high percentage of chymosin (around 78%). The effect of addition of starter on proteolysis was dependent on the casein fractions generated by artisanal lamb rennet or commercial calf rennet. © 2000 Society of Chemical Industry     

Coalho Cheese Made with Protease from Thermomucor indicae‐seudaticae N31: Technological Potential of the New Coagulant for the Production of High‐Cooked Cheese

The aim of this study was to explore the use of a new coagulant from Thermomucor indicae‐seudaticae N31 for the manufacture of a high‐cooked starter‐free cheese variety, by evaluating its physicochemical and functional characteristics in comparison to cheeses made with a traditional commercial coagulant. Coalho cheese was successfully produced with the new protease as it exhibited comparable characteristics to the one produced using the commercial enzyme: pH behavior during manufacture; cheese composition; protein and fat recovery; and cheese yield. In addition, during storage, melting was low and not affected by storage time; the increase of TCA 12% soluble nitrogen (% of total nitrogen) was lower than half of that of pH 4.6 soluble nitrogen (% of total nitrogen); concentration of β‐CN significantly decreased, whereas α_s1‐CN concentration was not affected by storage time.     

Effects of Penicillium roqueforti and whey cheese on gross composition,microbiology and proteolysis of mould‐ripened Civil cheese during ripening

Four different types of mould‐ripened Civil cheese were manufactured. A defined (nontoxigenic) strain of a Penicillium roqueforti (SC 509) was used as the secondary starter with and without addition of the whey cheese (Lor); in parallel, secondary starter‐free counterparts were manufactured. Chemical composition, microbiology and proteolysis were studied during the ripening. The incorporation of whey cheese in the manufacture of mould‐ripened Civil cheese altered the gross composition and adversely affected proteolysis in the cheeses. The inoculated P. roqueforti moulds appeared to grow slowly on those cheeses, and little proteolysis was evident in all cheese treatments during the first 90 days of ripening. However, sharp increases in the soluble nitrogen fractions were observed in all cheeses after 90 days. Microbiological analysis showed that the microbial counts in the cheeses were at high levels at the beginning of ripening, while their counts decreased approximately 1–2 log cfu/g towards the end of ripening.     

Cheese yeasts

Numerous traditionally aged cheeses are surface ripened and develop a biofilm, known as the cheese rind, on their surfaces. The rind of such cheeses comprises a complex community of bacterial and fungal species that are jointly responsible for the typical characteristics of the various cheese varieties. Surface ripening starts directly after brining with the rapid colonization of the cheese surface by yeasts. The initially dominant yeasts are acid and salt-tolerant and are capable of metabolizing the lactate produced by the starter lactic acid bacteria and of producing NH₃ from amino acids. Both processes cause the pH of the cheese surface to rise dramatically. This so-called deacidification process enables the establishment of a salt-tolerant, Gram-positive bacterial community that is less acid-tolerant. Over the past decade, knowledge of yeast diversity in cheeses has increased considerably. The yeast species with the highest prevalence on surface-ripened cheeses are Debaryomyces hansenii and Geotrichum candidum, but up to 30 species can be found. In the cheese core, only lactose-fermenting yeasts, such as Kluyveromyces marxianus, are expected to grow. Yeasts are recognized as having an indispensable impact on the development of cheese flavour and texture because of their deacidifying, proteolytic, and/or lipolytic activity. Yeasts are used not only in the production of surface-ripened cheeses but also as adjunct cultures in the vat milk in order to modify ripening behaviour and flavour of the cheese. However, yeasts may also be responsible for spoilage of cheese, causing early blowing, off-flavour, brown discolouration, and other visible alterations of cheese.     

Influence of exopolysaccharide‐producing cultures on the volatile profile and sensory quality of low‐fat Tulum cheese during ripening

The objective of this investigation was to compare the composition and changes in the concentration of volatiles in low‐fat and full‐fat Tulum cheeses during ripening. Tulum cheese was manufactured from low‐ or full‐fat milk using exopolysaccharide (EPS)‐producing or non‐EPS‐producing starter cultures. A total of 82 volatile compounds were identified belonging to the following chemical groups: acids (seven), esters (21), ketones (14), aldehydes (six), alcohols (14) and miscellaneous compounds (20). The relative amounts of acids, alcohols and aldehydes increased in the cheeses made with EPS‐producing cultures during 90 days of ripening. Differences were found in the volatile profile of full‐fat Tulum cheese compared with the low‐fat variant, especially after 90 days of ripening. Exopolysaccharide‐producing cultures changed the volatile profile, and the EPS‐producing cultures including Streptococcus thermophilus + Lactobacillus delbrueckii subsp. bulgaricus + Lactobacillus helveticus (LF‐EPS2) produced cheese with higher levels of methyl ketones and aldehydes than the non‐EPS cultures. In the sensory analysis, full‐fat Tulum cheeses and the cheese produced with the EPS‐producing culture containing Lb. helveticus (LF‐EPS2) were preferred by the expert panel. It was concluded that the use of EPS‐producing starter cultures in the manufacture of low‐fat Tulum cheese had the potential to improve the flavour.     

Utilization of freeze-shocked lactobacilli for enhancing flavour development of Ras cheese

Freeze-shocked cultures of Lactobacillus helveticus or Lactobacillus casei were added at levels of 1% and 2% to Ras cheese milk prior to renneting as an adjunct starter to enhance flavour development of cheese. These additives did not affect the gross chemical composition of the cheeses but increased the formation of soluble nitrogenous compounds, free volatile fatty acids, the flavour intensity and improved the body characteristic. Also, the counts of bacterial groups (total, proteolytic and lipolytic) of the cheese treated with freeze-shocked lactobacilli were higher than in the control. Moreover, the ripening period was reduced to be 2 months compared with 4 months required for the control cheese. Also, using freeze-shocked culture of L. helveticus was the most effective in this respect.     

Effects of coagulant type on the physicochemical and organoleptic properties of Kashar cheese

Kashar cheeses were manufactured using different coagulants (calf rennet, chymosin derived by fermentation and proteases from Rhizomucor miehei and Cryphonectria parasitica) and ripened for 90 days. Use of different coagulants did not influence the dry matter, fat, protein, salt, pH, titratable acidity, total free fatty acids and texture profile analyses. The levels of water‐soluble nitrogen, 12% trichloroacetic acid‐soluble nitrogen, and for 5% phosphotungstic acid‐soluble nitrogen, the sensory properties were significantly influenced by the use of different coagulants. β‐casein was more hydrolysed in the cheese manufactured using protease from Cryphonectria parasitica than the other cheeses during 90 d of ripening.     

Effect of soy protein supplementation on the quality of ripening Cheddar-type cheese

The impact of soy protein isolate on the proteolysis and organoleptic properties of Cheddar-type cheese during ripening was studied. Cheese was prepared from cow's milk (control) and cow's milk plus soy protein isolate by using a starter culture of Streptococcus thermophilus and Lactobacillus delbrueckii subsp . bulgaricus, and then ripened at 12  ±  1°C for 3 and 5 months. The molecular weight range and peptide fraction in the cheeses were determined by high-performance liquid chromatography (HPLC), and the microstructure was observed by scanning electron microscopy (SEM). Sensory evaluation was used to compare the flavour, body, texture and appearance of the cheeses. The results show that the molecular weight range (9924–9966  Da) in the control cheese was larger than that (6954–6957   Da) in the soy protein-treated cheese and the microstructure in the latter was less compact than in the control cheese. In the sensory evaluation, higher scores were given for some experimental cheese than the control cheese. After 5 months of ripening, the organoleptic properties of the cheese had markedly improved and no bitter off-flavour was detected in the treated cheeses. It was concluded that soy protein could be used to improve the quality of cheese and the addition of 5% soy protein isolate could be recommended for improving the flavour and texture of Cheddar-type soy supplemented cheese.     

Improving the quality of Ras cheese made without starter

Trials were carried out to produce Ras cheese of good quality without the use of starter. Cheese was made from cows' milk, pasteurized and acidified with lactic acid or citric acid to pH 5·8; cheese was also made after adding 4·5 g glucono-δ-lactone per kg to the acidified curd. Control cheese was made by the traditional method.The cheese had poor body and texture, weak flavour intensity, and low levels of soluble nitrogen compounds and free volatile fatty acids.Incorporation into the cheese curd of mixtures containing Fromase 100 (fungal protease) and Piccantase B (fungal lipase) or Fromase 100 and Capalase K (animal lipase) enhanced flavour intensity and body characteristics and accelerated the formation of both soluble nitrogen compounds and free volatile fatty acids. The organoleptic properties of the experimental cheese with added enzymes were comparable to the control cheese.     

Effect of a hygienized rennet paste and a defined strain starter on proteolysis,texture and sensory properties of semi-hard goat cheese

A hygienized rennet paste (HRP) and a defined strain starter culture, including Lactobacillus casei subsp. casei IFPL as adjunct, were considered for manufacturing Majorero cheese, a Spanish traditional variety made from goat milk. Influence of both factors on physicochemical characteristics, proteolysis, rheological and sensory properties, was evaluated throughout the ripening. Cheeses produced either industrially (IL) or in artisanal manner (AL) were compared with the experimental lot (EL), which included HRP and IFPL starter in its manufacture. Results showed a low level of primary proteolysis, expressed by a low content of non-casein nitrogen (NCN), in experimental cheeses. Despite the slightly poor texture (hard and crumbly) related to the high TS and salt contents, a good general acceptability was attained for EL, with the best scores for aroma and flavour intensities achieved at 30 ripening days. In fact, the sensory panel detected the “piquant” flavour (typical of the artisanal cheese variety) in EL after 15 days of ripening.