The effects of lipase‐encapsulating carriers on the accelerated ripening of Kashar cheese

In this study, lipase enzymes were encapsulated in κ‐carragenan, gellan and sodium alginate using emulsion and extrusion techniques and were then added to cheese milk together with rennet. The effects of the encapsulating material and ripening period on the chemical, textural and sensory characteristics of Kashar cheese were investigated. The study demonstrated that sodium alginate, gellan and κ‐carrageenan could successfully be used as lipase carrier systems to accelerate the fat breakdown process during the ripening of Kashar cheese. Those samples treated with κ‐carrageenan capsules showed the highest rate of lipolysis and proteolysis compared to those treated with the other capsules.     

Utilization of interesterified fat in the production of Turkish white cheese

The chemical, physicochemical, proteolysis, sensory, and texture characteristics of white cheeses made from interesterified fat were examined throughout ripening for 90 days. The water-soluble nitrogen based ripening indexes of cheeses increased throughout the ripening period. However, there were not large quantitative differences between the peptide profiles of the all cheese samples. Cheeses produced by using fully interesterified fat had higher values for hardness, chewiness, and gumminess than that of control cheese (p<0.05). The polyunsaturated to saturated fatty acid ratios of cheeses were increased due to the presence of interesterified fat. The cholesterol values of cheeses decreased at the rate of between 58.83–89.04% depending on interesterified fat addition. In the sensory analysis, similar scores were obtained for both the control cheese and the other cheeses. The results showed that interesterified fat in cheese production could be used to fully or partially replace the milk fat in cheese.     

Proteolysis and biogenic amine buildup in high-pressure treated ovine milk blue-veined cheese

Penicillium roqueforti plays an important role in the ripening of blue-veined cheeses, mostly due to lactic acid consumption and to its extracellular enzymes. The strong activity of P. roqueforti proteinases may bring about cheese over-ripening. Also, free amino acids at high concentrations serve as substrates for biogenic amine formation. Both facts result in shorter product shelf-life. To prevent over-ripening and buildup of biogenic amines, blue-veined cheeses made from pasteurized ovine milk were high-pressure treated at 400 or 600 MPa after 3, 6, or 9 wk of ripening. Primary and secondary proteolysis, biogenic amines, and sensory characteristics of pressurized and control cheeses were monitored for a 90-d ripening period, followed by a 270-d refrigerated storage period. On d 90, treatments at 400 MPa had lowered counts of lactic acid bacteria and P. roqueforti by less than 2 log units, whereas treatments at 600 MPa had reduced lactic acid bacteria counts by more than 4 log units and P. roqueforti counts by more than 6 log units. No residual α-casein (CN) or κ-CN were detected in control cheese on d 90. Concentrations of β-CN, para-κ-CN, and γ-CN were generally higher in 600 MPa cheeses than in the rest. From d 90 onwards, hydrophilic peptides were at similar levels in pressurized and control cheeses, but hydrophobic peptides and the hydrophobic-to-hydrophilic peptide ratio were at higher levels in pressurized cheeses than in control cheese. Aminopeptidase activity, overall proteolysis, and free amino acid contents were generally higher in control cheese than in pressurized cheeses, particularly if treated at 600 MPa. Tyramine concentration was lower in pressurized cheeses, but tryptamine, phenylethylamine, and putrescine contents were higher in some of the pressurized cheeses than in control cheese. Differences in sensory characteristics between pressurized and control cheeses were generally negligible, with the only exception of treatment at high pressure level (600 MPa) at an early ripening stage (3 wk), which affected biochemical changes and sensory characteristics.     

Study of macromolecular interactions in low‐fat brined cheese modified with Zedu gum

The functionality of Zedu gum as a fat mimetic in low‐fat brined cheese was studied. The physicochemical, textural, rheological, microstructural and sensory properties of cheese samples modified with 0.1% and 0.25% of Zedu gum were compared to those of control cheeses (low‐fat and full‐fat cheeses with no fat mimetic) during ripening. To obtain further information about the cheeses' structure and interactions between macromolecules (casein protein and Zedu gum), other parameters were analysed by differential scanning calorimetry and Fourier transform infrared (FTIR) spectroscopy. Incorporation of Zedu gum into low‐fat cheese caused an open microstructure and softer texture in comparison with the control low‐fat cheese. The thermal properties and FTIR spectra of the cheeses were influenced by both fat mimetic and ripening time. On days 1 and 60 of ripening time, the lower value of enthalpy of the low‐fat cheese with 0.25 g of Zedu gum/kg of milk (AS 0.25) in comparison with control low‐fat cheese could have been due to the electrostatic nature of the interactions between Zedu gum and casein protein. On both days, the FTIR spectrum of AS 0.25 showed a well separated absorption at 1746 cm^?1 possibly due to the formation of ester groups as a result of the interaction of the carbonyl groups in Zedu gum with the hydroxyl groups of some amino acids in casein.     

Effects of genetic type,stage of lactation,and ripening time on Caciocavallo cheese proteolysis

The objective of this experiment was to evaluate the effects of genetic type, stage of lactation, and ripening time on proteolysis in Caciocavallo cheese. One hundred twenty Caciocavallo cheeses made from the milk of 2 breeds, Italian Brown and Italian Holstein and characterized by different stages of lactation were obtained and ripened for 1, 30, 60, 90, and 150 d. Cheese proteolysis was investigated by ripening index (ratio of water-soluble N at pH 4.6 to total protein, %) and by the study of degradation of the protein fractions (α_S1-, β-, and para-κ-casein), which was determined by densitometric analysis of isoelectric focusing results. The statistical analysis showed a significant effect of the studied factors. Ripening index was higher in Italian Brown Caciocavallo cheese and in cheeses made with early lactation milk, whereas casein solubilization was greater in the first 2 mo of ripening. Isoelectric focusing analysis of cheese samples during ripening showed extensive hydrolysis of caseins. In particular, the protein fraction that underwent major degradation by proteolytic enzymes was α_S1-casein, followed by β-casein, whereas para-κ-casein was less degraded. Italian Brown cheese showed a lower residual quantity of β- and para-κ-casein, whereas Italian Holstein cheese showed a lower residual quantity of α_S1-casein. In addition, significant interactions of both first and second order were found on both ripening index and degradation of protein fractions. This study demonstrated that the analyzed factors influenced proteolysis of Caciocavallo cheese, which forms the basis of new knowledge that could lead to the production of a pasta filata cheese with specific characteristics.     

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.     

Influence of fat replacers on chemical composition, proteolysis, texture profiles, meltability and sensory properties of low-fat Kashar cheese

Changes in chemical composition, proteolysis, lipolysis, texture, melting and sensory properties of low-fat Kashar cheese made with three different fat replacers (Simplesse D-100, Avicel Plus CM 2159 or beta-glucan) were investigated throughout ripening. The low-fat cheeses made with fat replacers were compared with full- and low-fat counterparts as controls. Reduction of fat caused increases in moisture and protein contents and decreases in moisture-in-non fat substance and yield values in low-fat cheeses. The use of fat replacers in the manufacture of low-fat Kashar cheese increased water binding capacity and improved overall quality of the cheeses. Use of fat replacer in low-fat cheese making has enhanced cheese proteolysis. All samples underwent lipolysis during ripening and low-fat cheeses with fat replacers had higher level of total free fatty acid than full- or low-fat control cheeses. Texture attributes and meltability significantly increased with addition of fat replacers. Sensory scores showed that the full-fat cheese was awarded best in all stages of ripening and low-fat variant of Kashar cheeses have inferior quality. However, fat replacers except beta-glucan improved the appearance, texture and flavour attributes of low-fat cheeses. When the fat replacers are compared, the low-fat cheese with Avicel Plus CM 2159 was highly acceptable and had sensory attributes closest to full-fat Kashar cheese.     

Microencapsulation of Cell-Free Extracts to Demonstrate the Feasibility of Heterogeneous Enzyme Systems and Cofactor Recycling for Development of Flavor in Cheese

A mixture of a cell-free extract from Gluconobacter oxydans that produced acetic acid from ethanol and a cell-free extract from Streptococcus lactis var. maltigenes, which converted leucine to 3-methylbutanal and 3-methylbutanol, were coencapsulated with substrate and nicotinamide adenine dinucleotide in a milk fat coat. The capsules were incubated as 12.8, 22, and 32°C to measure production of 3-methylbutanal, 3-methylbutanol, and acetic acid and recycling of nicotinamide adenine dinucleotide/reduced nicotinamide adenine dinucleotide. Maximum amounts of 3-methylbutanal and 3-methylbutanol were produced after 48 h at 22°C, demonstrating the feasibility of encapsulating a combined CFE to recycle cofactors and produce an array of products. Capsules containing the combined cell-free extract were added to skim milk and milk containing 1.1% fat to produce cheeses with reduced fat. About 16% of the capsules were lost in whey during manufacturing of cheese from skim milk with added capsules but less for cheese made with 1.1% fat plus capsules. During ripening at 7.2 and 12.8°C for 1, 3, and 6 mo, cheeses containing whole capsules with a complete cell-free extract mixture contained more 3-methylbutanal and 3-methylbutanol and exhibited a stronger malty taste than cheeses made with broken capsules or an incomplete cell-free extract mixture.     

Proteolysis in goat cheese made from raw,pasteurized or pressure-treated milk

Primary and secondary proteolysis of goat cheese made from raw (RA), pasteurized (PA; 72 °C, 15 s) and pressure-treated milk (PR; 500 MPa, 15 min, 20 °C) were examined by capillary electrophoresis, nitrogen fractionation and HPLC peptide profiles. PA milk cheese showed a more important hydrolysis (P<0.05) of α_s1-casein than RA milk cheese at the first stages of ripening (15 days), while PR milk cheese had a level between those seen in PA and RA milk cheeses. Degradation of β-casein was more important (P<0.05) in PA and PR than in RA milk cheeses at 15 days of ripening. However, from thereon β-casein in PR and RA milk cheeses was hydrolyzed at essentially similar rates, but at lower rates (P<0.05) than in PA milk cheeses. Pressure treatment could induce proteolysis of β-casein in a way, which is different from that produced by heat treatment. There was an increase in 4.6-soluble nitrogen (WSN) and in trichloroacetic acid (TCASN) throughout ripening in cheeses, but higher contents (P<0.05) in PA and PR milk cheeses at the end of ripening were observed. PR milk cheeses contained considerably higher content (P<0.05) of free amino acids than RA or PA milk cheeses. In general, heat and pressure treatments had no significant effect on the levels of hydrophobic and hydrophilic peptides.     

Accelerated Cheddar Cheese Ripening by Added Microbial Enzymes

Good quality medium sharp Cheddar cheeses with 3-mo curing at 10 C were produced when the following enzyme combinations and concentrations were used: fungal protease 31000 (Miles), .005% + fungal lipase-MY (Meito) .00005 to .0002%; and fungal protease P-53 (Rohm & Haas), .0035% + fungal lipase-MY (Meito), .00005 to .0002%.Cheddar cheeses treated with microbial enzymes developed higher soluble protein and free volatile fatty acids and displayed better flavor and greater acceptability than control cheeses. Added microbial proteases contributed to the breakdown of casein, especially β-casein. Also, αs₁-I casein and free amino acids were high in cheeses treated with protease. Increased rate of proteolysis in enzyme-treated cheese had a direct relation to accelerated ripening.     

Utilization of microfiltration or lactoperoxidase system or both for manufacture of Cheddar cheese from raw milk

The objective of the present study was to determine if application of microfiltration (MF) or raw milk lactoperoxidase system (LP) could reduce the risk of foodborne illness from Escherichia coli in raw milk cheeses, without adversely affecting the overall sensory acceptability of the cheeses. Escherichia coli K12 was added to raw milk to study its survival as a non-pathogenic surrogate organism for pathogenic E. coli. Five replications of 6 treatments of Cheddar cheese were manufactured. The 6 treatments included cheeses made from pasteurized milk (PM), raw milk (RM), raw milk inoculated with E. coli K12 (RME), raw milk inoculated with E. coli K12 + LP activation (RMELP), raw milk inoculated with E. coli K12 + MF (MFE), and raw milk inoculated with E. coli K12 + MF + LP activation (MFELP). The population of E. coli K12 was enumerated in the cheese milks, in whey/curds during cheese manufacture, and in final Cheddar cheeses during ripening. Application of LP, MF, and a combination of MF and LP led to an average percentage reduction of E. coli K12 counts in cheese milk by 72, 88, and 96%, respectively. However, E. coli K12 populations significantly increased during the manufacture of Cheddar cheese for the reasons not related to contamination. The number of E. coli K12, however, decreased by 1.5 to 2 log cycles during 120 d of ripening, irrespective of the treatments. The results suggest that MF with or without LP significantly lowers E. coli count in raw milk. Hence, if reactivation of E. coli during cheese making could be prevented, MF with or without LP would be an effective technique for reducing the counts of E. coli in raw milk cheeses. The cheeses were also analyzed for proteolysis, starter and nonstarter lactic acid bacteria (NSLAB), and sensory characteristics during ripening. The concentration of pH 4.6 soluble nitrogen at 120 d was greater in PM cheese compared with the other treatments. The level of 12% trichloroacetic acid-soluble nitrogen at 120 d was greater in RM, RME, and RMELP cheeses compared with PM, MFE, and MFELP cheeses. This could be related to the fact that cheeses made from raw milk with or without LP (RM, RME, and RMELP) had greater levels of NSLAB compared with PM, MFE, and MFELP cheeses. Cheeses at 60 d, as evaluated by 8 trained panelists, did not differ in bitterness, pastiness, or curdiness attributes. Cheeses at 120 d showed no differences in acid-taste, bitterness, or curdiness attributes. Sensory analysis at 60 d showed that PM and MFELP cheeses had greater overall sensory acceptability than RM and RME cheeses. The overall sensory acceptability of the cheeses at 120 d showed that PM, MFE, and MFELP cheeses were more acceptable than RM and RME cheeses.     

Proteolytic activity of three probiotic strains in semi-hard cheese as single and mixed cultures: Lactobacillus acidophilus,Lactobacillus paracasei and Bifidobacterium lactis

The influence of three probiotic strains (Lactobacillus acidophilus, Lactobacillus paracasei and Bifidobacterium lactis) in semi-hard cheese proteolysis patterns was assessed. Probiotics were inoculated both as single cultures and as a three-strain mix, and added to milk either after a pre-incubation step or directly to the vat. B. lactis did not show any effect on proteolysis of cheeses, while L. paracasei showed limited impact at the end of the ripening. In contrast, L. acidophilus significantly influenced secondary proteolysis from the beginning of ripening, causing an increase in the levels of small nitrogen-containing compounds and free amino acids and changes in the peptide profiles. The effect of Lactobacillus acidophilus on peptidolysis was more noticeable when it was added to cheese–milk after pre-incubation in an enriched milk fat substrate. Similar results obtained with the three-strain mixed culture, suggesting that L. acidophilus played a major role in secondary proteolysis of probiotic cheeses in this trial.     

Influence of microfiltration and adjunct culture on quality of Domiati cheese

The effects of microfiltration and pasteurization processes on proteolysis, lipolysis, and flavor development in Domiati cheese during 2 mo of pickling were studied. Cultures of starter lactic acid bacteria isolated from Egyptian dairy products were evaluated in experimental Domiati cheese for flavor development capabilities. In the first trial, raw skim milk was microfiltered and then the protein:fat ratio was standardized using pasteurized cream. Pasteurized milk with same protein:fat ratio was also used in the second trial. The chemical composition of cheeses seemed to be affected by milk treatment—microfiltration or pasteurization—rather than by the culture types. The moisture content was higher and the pH was lower in pasteurized milk cheeses than in microfiltered milk cheeses at d 1 of manufacture. Chemical composition of experimental cheeses was within the legal limits for Domiati cheese in Egypt. Proteolysis and lipolysis during cheese pickling were lower in microfiltered milk cheeses compared with pasteurized milk cheeses. Highly significant variations in free amino acids, free fatty acids, and sensory evaluation were found among the cultures used in Domiati cheesemaking. The cheese made using adjunct culture containing Lactobacillus delbrueckii ssp. lactis, Lactobacillus paracasei ssp. paracasei, Lactobacillus casei, Lactobacillus plantarum, and Enterococcus faecium received high scores in flavor acceptability. Cheeses made from microfiltered milk received a higher score in body and texture compared with cheeses made from pasteurized milk.     

Yield,changes in proteolysis,and sensory quality of Prato cheese produced with different coagulants

The objective of this research was to compare the effect of 2 fungal proteases, one that is already commercially established as a milk-clotting agent and another produced at the laboratory scale, on Prato cheese composition, protein and fat recovery, yield, and sensory characteristics. Cheeses were produced according to the traditional protocol, using protease from the fungus Thermomucor indicae-seudaticae N31 and commercial coagulant from Rhizomucor spp. as clotting agents. A 2 × 6 factorial design with 3 replications was performed: 2 levels of coagulants and 6 levels of storage time. After 5, 12, 19, 33, 43, and 53 d of refrigerated storage (12°C), cheeses were monitored for proteolysis, firmness, and casein degradation by capillary electrophoresis. Sensory acceptance was evaluated after 29 d of manufacturing. The different coagulants did not statistically affect Prato cheese composition, protein and fat recovery, and yield. Both cheeses presented good sensory acceptance. Proteolysis increased and firmness decreased for both cheeses during the storage time, as expected for Prato cheese. Caseins were well separated by capillary electrophoresis and the results showed, with good resolution, that the cheeses exhibited similar protein hydrolysis profile. Both cheeses presented good sensory acceptance. The gathered data showed that the protease from T. indicae-seudaticae N31 presented similar action compared with the commercial enzyme, indicating its efficiency as clotting agent for Prato cheese manufacture.     

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.     

Texture of low-fat Iranian White cheese as influenced by gum tragacanth as a fat replacer

The effect of different concentrations of gum tragacanth on the textural characteristics of low-fat Iranian White cheese was studied during ripening. A batch of full-fat and 5 batches of low-fat Iranian White cheeses with different gum tragacanth concentrations (without gum or with 0.25, 0.5, 0.75, or 1 g of gum/kg of milk) were produced to study the effects of fat content reduction and gum concentration on the textural and functional properties of the product during ripening. Cheese samples were analyzed with respect to chemical, color, and sensory characteristics, rheological parameters (uniaxial compression and small-amplitude oscillatory shear), and microstructure. Reducing the fat content had an adverse effect on cheese yield, sensory characteristics, and the texture of Iranian White cheese, and it increased the instrumental hardness parameters (i.e., fracture stress, elastic modulus, storage modulus, and complex modulus). However, increasing the gum tragacanth concentration reduced the values of instrumental hardness parameters and increased the whiteness of cheese. Although when the gum concentration was increased, the low-fat cheese somewhat resembled its full-fat counterpart, the interaction of the gum concentration with ripening time caused visible undesirable effects on cheese characteristics by the sixth week of ripening. Cheeses with a high gum tragacanth concentration became very soft and their solid texture declined somewhat.     

Starter strain related effects on the biochemical and sensory properties of Cheddar cheese

A detailed investigation was undertaken to determine the effects of four single starter strains, Lactococcus lactis subsp. lactis 303, Lc. lactis subsp. cremoris HP, Lc. lactis subsp. cremoris AM2, and Lactobacillus helveticus DPC4571 on the proteolytic, lipolytic and sensory characteristics of Cheddar cheese. Cheeses produced using the highly autolytic starters 4571 and AM2 positively impacted on flavour development, whereas cheeses produced from the poorly autolytic starters 303 and HP developed off-flavours. Starter selection impacted significantly on the proteolytic and sensory characteristics of the resulting Cheddar cheeses. It appeared that the autolytic and/or lipolytic properties of starter strains also influenced lipolysis, however lipolysis appeared to be limited due to a possible lack of availability or access to suitable milk fat substrates over ripening. The impact of lipolysis on the sensory characteristics of Cheddar cheese was unclear, possibly due to minimal differences in the extent of lipolysis between the cheeses at the end of ripening. As anticipated seasonal milk supply influenced both proteolysis and lipolysis in Cheddar cheese. The contribution of non-starter lactic acid bacteria towards proteolysis and lipolysis over the first 8 months of Cheddar cheese ripening was negligible.     

Residual clotting activity and ripening properties of vegetable rennet from Cynara cardunculus in La Serena cheese

Vegetable rennet extracted from Cynara cardunculus flowers is traditionally used in the manufacture of La Serena cheese. High levels of proteolytic enzymes of the flowers are responsible for its clotting activity and strong proteolytic action. The presence of residual coagulant in cheese and whey was measured by adding known amounts of vegetable rennet as internal standard. We found no differences between the residual coagulant activity of La Serena cheese compared with other types of cheese. The coagulant content detected at the end of four cheesemakings (vat of 830 l) in cheese and whey represented 27 and 78%, respectively, of the total amount added to milk. When measurements were carried out in 16 different cheeses, vegetable rennet appeared to be highly stable during cheese ripening. Cheese composition (moisture, pH, NaCl, fat and protein) was kept relatively constant during ripening, which seems to contribute to stability of residual activity. Electrophoretic analyses of water insoluble fractions from cheeses manufactured with vegetable rennet showed that α_s-casein was less susceptible to proteolysis than β-casein. The water soluble nitrogen/total nitrogen (WSN/TN) exhibited higher levels only during the first 30 days of ripening although non-protein nitrogen/total nitrogen (NPN/TN) ratio and amino acid nitrogen (NH₂-N) increased with ripening time.