Influence of the technological properties of vegetable rennet (Cynara cardunculus) on the physicochemical,sensory and rheological characteristics of ‘Torta del Casar’ cheese

The purpose of this work was to investigate the influence of technological properties of vegetable rennet (Cynara cardunculus) on the characteristics of ‘Torta del Casar’ cheese to establish the parameters that can be useful for quality control of this coagulant. The physicochemical, microbial, texture and sensory properties of the cheeses were evaluated and correlated to clotting and proteolytic activities of the vegetable rennets used for their manufacture. The level of in vitro degradation of α‐casein and κ‐casein/β‐casein degradation ratio was found to be good tools to predict the effect of vegetable rennet on the rheological properties of these cheeses.     

Effect of β-casein concentration in cheese milk on rennet coagulation properties,cheese composition and cheese ripening

Effects of the use of a β-casein powder to enrich cheese milk on rennet coagulation properties of milk, cheese composition and cheese ripening were investigated. Casein content of control milk was 2.5%, whereas that for the three enriched milks was adjusted with β-casein powder at 2.7%, 2.9% and 3.1%. The β-casein to α-casein ratio of these cheese milks was, respectively, 0.70, 0.79, 0.89 and 0.99. Rennet coagulation properties were related not only to casein concentration but also to the proportion of β-casein and α_s-casein presents in milks. Milk with higher concentration of β-casein had poorer coagulation properties. Cheeses could be produced by using a miniature cheese making process. Moisture, ash and calcium contents decreased, while protein content and β-casein increased in cheese as casein and β-casein concentration increased in milk. As a result, hardness was higher in enriched cheeses than in control cheese. During cheese ripening, α-casein was hydrolyzed, but the rate of degradation of α-casein decreased as protein and β-casein concentration increased in cheese. β-Casein seemed to be not hydrolyzed. The rate of decrease of hardness was also slower for enriched cheeses.     

Enzymatic extract from flowers of Algerian spontaneous Cynara cardunculus: Milk‐clotting properties and use in the manufacture of a Camembert‐type cheese

The aim of this study was to assess the coagulant properties of crude extract from cardoon flowers (CECF) as a replacement for the imported coagulants used in the local Algerian cheese factories. Optimal coagulation activity of the extract was observed at pH 5 and 60 °C with a CaCl₂ concentration of 0.02 M. The electrophoretic pattern revealed that the crude extract contains mainly cardosins A and B. The study of interactions involved in the formation of milk gel coagulated by CECF showed that hydrogen forces, hydrophobic interactions and calcium bridges contributed highly to the formation of milk gel. Camembert‐type cheese obtained by CECF was judged by trained panellists and was found to be in agreement with standard specifications. The present study highlights the possibility of using Algerian CECF as a promising plant coagulant in cheesemaking for the dairy industry.     

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.     

Volatile compounds, odor, and aroma of La Serena cheese high-pressure treated at two different stages of ripening

La Serena cheeses made from raw Merino ewe's milk were high-pressure (HP) treated at 300 or 400 MPa for 10 min on d 2 or 50 after manufacture. Ripening of HP-treated and control cheeses proceeded until d 60 at 8°C. Volatile compounds were determined throughout ripening, and analysis of related sensory characteristics was carried out on ripe cheeses. High-pressure treatments on d 2 enhanced the formation of branched-chain aldehydes and of 2-alcohols except 2-butanol, but retarded that of n-aldehydes, 2-methyl ketones, dihydroxy-ketones, n-alcohols, unsaturated alcohols, ethyl esters, propyl esters, and branched-chain esters. Differences between HP-treated and control cheeses in the levels of some volatile compounds tended to disappear during ripening. The odor of ripe cheeses was scarcely affected by HP treatments on d 2, but aroma quality and intensity scores were lowered in comparison with control cheese of the same age. On the other hand, HP treatments on d 50 did not influence either the volatile compound profile or the sensory characteristics of 60-d-old cheese.     

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     

Influence of lamb rennet paste on composition and proteolysis during ripening of Pecorino foggiano cheese

Rennet pastes produced by lambs subjected to three different feeding systems (mother suckling [MS], artificial rearing [AR], and artificial rearing with Lactobacillus acidophilus supplementation [ARLB]) and slaughtered at two different ages (20 and 40 d) were used for the manufacture of Pecorino foggiano cheese. Composition and proteolysis during ripening of Pecorino foggiano cheese (four replicates batches) were analyzed. Proteolysis was greater in cheeses made with rennet pastes from lambs slaughtered at 20 d, as shown by analysis of nitrogen fractions (water-soluble N and proteose peptones). Supplementation of milk substitute with L. acidophilus may have influenced the growth dynamics of lactic acid bacteria in the rennet pastes, with positive effects on levels of lactobacilli in cheese at the beginning of the ripening time. Lower pH values in ARLB cheese during ripening, together with higher cell loads, suggest that supplementation of milk replacer with L. acidophilus resulted in higher proteolytic activity, as also confirmed by the composition of the pH 4.6—insoluble nitrogen fraction. No differences were found in total concentration of free amino acids among the experimental cheeses; phenylalanine, isoleucine, leucine, lysine were found at the highest levels. The addition of probiotic bacteria to milk substitute in lamb rearing appears to give good-quality lamb rennet paste.     

Influences of rennet and container types on proteolysis of traditional Kurdish cheese during the ripening

The effect of rennet and container types was evaluated on proteolysis of traditional Kurdish cheese during 60 days ripening. The enzymes involved were commercial chymosin and traditional rennet from lamb abomasum. Goat skin (traditional container) and plastic containers were used as storage containers. The trend of proteolysis was determined by measuring the content of nitrogen (N) in compounds soluble in water, 12% trichloroacetic acid and 5% phosphotungstic acid along with the urea–polyacrylamide gel electrophoresis method. The results showed that the nitrogen in compounds soluble in water, 12% trichloroacetic acid and 5% phosphotungstic acid was higher in ripened cheeses into plastic containers; however, the containers had no significant effect on the breakdown of α‐ and β‐caseins (P < 0.05). Using commercial rennet caused the breakdown of α‐ and β‐caseins and the level of nitrogen in compounds soluble in water to increase. Finally, however, the amount of α‐ and β‐caseins breakdown was trivial, and α‐casein was decreased more than β‐casein in all samples.     

Cheese-making properties of vegetable rennet from sodom apple (Calotropis procera)

Yield, chemical composition and texture profile of cheese made with vegetable rennet from sodom apple leaves were compared with those of a direct acid cheese made with calf rennet. Yield, moisture, fat and protein contents were 14·47%, 49·70%, 26·15% and 20·0%, respectively, for cheese made with vegetable rennet and 12·45%, 44·80%, 29·84% and 20·4%, respectively, for the direct acid cheese made with calf rennet. Cheese made with vegetable rennet had less soluble nitrogen than that made with calf rennet despite the fact that vegetable rennet was more proteolytic in casein solution than calf rennet. Relative to that made with calf rennet, cheese made with vegetable rennet was harder, less cohesive and more gummy, presumably because of differences in chemical composition and physical characteristics between the cheeses.     

Bioactive peptides in ovine and caprine cheeselike systems prepared with proteases from Cynara cardunculus

The potential angiotensin-converting enzyme (ACE)-inhibitory and antioxidant activities of peptides in water-soluble extracts, obtained from raw and sterilized ovine and caprine cheeselike systems coagulated with enzymes from the plant Cynara cardunculus, were assessed. Prior to the assay, the 3,000-Da permeate from 45-d-old cheeselike systems was fractionated by tandem chromatographic techniques. Several peaks were obtained in each chromatogram, but only some were associated with ACE-inhibitory or antioxidant activity or both. Peptides Tyr-Gln-Glu-Pro, Val-Pro-Lys-Val-Lys, and Tyr-Gln-Glu-Pro-Val-Leu-Gly-Pro-* from β-casein, as well as Arg-Pro-Lys and Arg-Pro-Lys-His-Pro-Ile-Lys-His-* from α_s1-casein exhibited ACE-inhibitory activity. Peptides released upon cleavage of the peptide bond Leu190-Tyr191 (either in ovine or caprine β-casein), and corresponding to the β-casein sequence Tyr-Gln-Glu-Pro-*, possessed antioxidant activity.     

The role of immobilized rennet on carbon cloth in flavor development during ripening of Gouda cheese

Rennet-free Gouda (RFG) cheese was prepared to investigate the influence of rennet on the non-volatile and volatile profiles of cheese and was characterized by HPLC and GC/MS analyses. Chymosin, a major protease in rennet, was immobilized onto oxidized and chemically modified carbon cloth. The chymosin immobilization efficiency was 60.4%, and the milk-clotting activity used as an index of the stability of the immobilized chymosin decreased by around 20% in 2 weeks. However, the activity was maintained at 70–80% from 2 weeks to 32 weeks and was more stable than that of chymosin solution alone. Non-volatile (organic acids) and volatile profiles of the RFG cheese and rennet-containing normal Gouda cheese were not significantly different during ripening with a few exceptions. Therefore, it can be concluded that cheese flavor is developed by lactic acid fermentation, irrespective of the presence of rennet.     

Studies pertaining to coagulant and proteolytic activities of plant proteases from Cynara cardunculus

Studies encompassing variation of milk clotting time with the concentration of proteases extracted from Cynara cardunculus were performed; milk clotting time dependence is not linear, and a model was postulated that fits well the experimental data obtained, and hence may be useful in predicting changes during the cheesemaking process. Parallel studies were also conducted pertaining to proteolysis of a mixture of ovine and caprine caseins, in attempts to investigate the stability of the aforementioned coagulating enzymes in crude or in pure form, with or without previous incubation for a certain time under typical ripening conditions. The enzymes exhibited an increase in activity whenever previous incubation had taken place. Moreover, the extent of enzyme-mediated proteolysis was always higher on caprine than on ovine milk caseins.     

Comparative biochemical evolution during ripening of bovine, ovine and caprine cheeses manufactured with extracts of flowers of Cynara cardunculus

Changes in the main physicochemical and biochemical characteristics of bovine, ovine and caprine milk cheeses manufactured with aqueous extracts of flowers of Cynara cardunculus were studied throughout ripening (0?–?68 days). At the end of ripening the pH in the centre was (mean ± ISD) 5.05±0.07, 5.15±0.21 and 4.91±0.07 for bovine, ovine and caprine milk cheeses, respectively; whereas the pH at the top of the cheese was 5.21±0.09, 5.44±0.12 and 5.12±0.07, respectively; the moisture content values of bovine, ovine and caprine milk cheeses were 37.68±2.32, 40.23±4.34 and 45.73±1.44%, respectively; the NaCl content values were 4.00±0.43, 4.00±0.56 and 4.08±0.58 (%TS); the fat content values were 41.01±5.32, 63.60±7.80 and 45.14±9.14 (%TS); the protein content values were 28.96±1.84, 22.89±2.37 and 30.02±1.22 (%TS); the water-soluble nitrogen values were 32.91±1.76, 46.44±1.86 and 48.72±1.08 (%TN); the values of nitrogen soluble in trichloroacetic acid were 10.25±1.93, 10.41±2.91 and 7.25±0.84 (%TN); the values of nitrogen soluble in phosphotungstic acid were 1.50±0.18, 1.87±0.65 and 1.38±0.32 (%TN); finally, the free amino acid content values were 21.33±5.34, 17.51±5.08 and 23.93±4.80 μM equivalents of leucine. Urea-polyacrylamide gel electrophoresis of water-insoluble fractions from cheeses indicated high degrees of proteolysis of α_s1-casein in bovine cheeses and more extensive proteolysis of the α_s-casein region in caprine than in ovine cheeses, but a moderate degree of proteolysis of β-casein in all types of cheese; electrophoregrams of the water-soluble fraction displayed increasing numbers of bands throughout ripening, an observation that is consistent with the increase in the ratio of water-soluble nitrogen to total nitrogen.     

Changes during manufacture and ripening of cheddar cheese prepared with fungal rennet substitute of Rhizopus oligosporus

Studies were made on the manufacture and ripening of cheddar cheese prepared with a milk-clotting enzyme of R. oligosporus and compared with rennet cheese. The curd working properties, yields and quality of green cheese from R. oligosporus enzyme were fairly comparable with calf-rennet. During the ripening period the changes in moisture, acidity, pH and fat content of both the cheese were similar. The soluble nitrogen was comparatively low while maturity index was higher during ripening in R. oligosporus cheese than calf-rennet cheese. Organoleptically, R. oligosporus cheese was rated lower than calf-rennet cheese, developing transient bitterness during ripening like other fungal rennet substitutes.     

Evolution of free fatty acid profile during ripening in cheeses manufactured from bovine, ovine and caprine milks with extracts of Cynara cardunculus as coagulant

 Changes in the concentrations of free fatty acids (FFA) in bovine, ovine and caprine milk cheeses manufactured with a plant rennet (flowers of Cynara cardunculus) were studied throughout a 68-day ripening period. The long-chain saturated (C16 : 0 and C18 : 0) and unsaturated (C18 : 1, C18 : 2, and C18 : 3) FFA were the most abundant at all stages of ripening. The overall concentration of FFA in fresh cheese was 3598, 3538 and 3868 mg/kg cheese for bovine, ovine and caprine milk cheeses, respectively; these values increased to 5047, 6517 and 5257 mg/kg cheese, respectively, by 68 days, of which 1171, 1734 and 1791 mg/kg cheese, respectively, were accounted for by C4 : 0 – C12 : 0. The FFA that showed the highest fractional increase by 68 days of ripening in bovine milk cheese were C4 : 0, C6 : 0, C8 : 0, C12 : 0, C18 : 1 and C18 : 2; in ovine milk cheese they were C4 : 0, C6 : 0, C8 : 0, C10 : 0, C14 : 0, and C18 : 1; and in caprine milk cheese they were C4 : 0, C8 : 0, C10 : 0, C14 : 0 and C18 : 1. Received: 2 August 1996     

Short communication: Inactivation of microbial contaminants in raw milk La Serena cheese by high-pressure treatments

La Serena cheese, a Spanish variety made from Merino ewes’ raw milk, has a high pH value, low salt content, and high moisture, conditions that are all favorable for growth and survival of contaminating microorganisms, including pathogens. To improve its microbiological quality and safety, high-pressure treatments at 300 or 400 MPa for 10 min at 10°C were applied to 2 batches of La Serena cheese on d 2 or 50 of ripening. Cheese treated on d 2 at 300 MPa showed viable aerobic counts that were 0.99 log units lower than those for control cheese on d 3 and showed counts of enterococci, coagulase-positive staphylococci, gram-negative bacteria, and coliforms that were 2.05, 0.49, 3.14, and 4.13 log units lower, respectively, than control cheese. For cheese treated on d 2 at 400 MPa, the respective reductions in counts were 2.02, 2.68, 1.45, 3.96, and 5.50 log units. On d 60, viable aerobic counts in cheese treated on d 50 at 300 MPa were 0.50 log units lower than those in control cheese, and counts of enterococci, gram-negative bacteria, and coliforms were 1.37, 2.30, and 4.85 log units lower, respectively. For cheese treated on d 50 at 400 MPa, the respective reductions in counts were 1.29, 1.98, 4.47, and > 5 log units. High-pressure treatments at 300 or 400 MPa on d 2 or 50 reduced significantly the counts of undesirable microorganisms, improving the microbiological quality and safety of La Serena cheese immediately after treatment and at the end of the ripening period.     

Effect of high-pressure treatments on proteolysis and texture of ewes’ raw milk La Serena cheese

La Serena cheeses, made from Merino ewes’ raw milk, were high-pressure (HP)-treated at 300 or 400 MPa for 10 min at 10 °C, on days 2 or 50 of ripening. Cheeses treated by HP on day 2 showed higher pH values than control cheese on day 3, but cheeses treated by HP on days 2 or 50 and control cheese had similar pH values on day 60. Breakdown of caseins was delayed by HP treatment of cheeses on day 2. Cheeses treated by HP on day 2 showed higher levels of hydrophilic peptides, lower levels of hydrophobic peptides, lower hydrophobic peptides: hydrophilic peptides ratios, and higher total contents of free amino acids than those of control cheese. HP treatment of cheese on day 50 scarcely affected proteolysis of 60-day-old cheeses. Fracturability, hardness and elasticity values of cheeses treated by HP on day 2 were higher than those of control cheese and of cheeses treated on day 50. Cheeses treated at 400 MPa on day 2 received the lowest scores for quality of taste from panellists, whereas the rest of HP-treated cheeses did not differ from control cheese.