Trichloroacetic Acid-soluble Nitrogen Research Articles

The role of microbial coagulants on the physicochemical, proteolysis, microstructure and sensory properties of low-fat Edam cheese manufactured from ultrafiltered buffalo milk

This work investigates the influence of using microbial coagulants, including Rhizomucor miehei (MCR) protease and Cryphonectria parasitica (MCC) protease, on the quality characteristics of low-fat Edam cheese made from ultrafiltered buffalo milk (LFUE). Concurrently, a benchmark with calf rennet (CR) has been also performed. Throughout a 90-day ripening period, the cheeses were assessed for their physicochemical features, proteolysis, texture, free amino acid and free fatty acid content, microstructure, and sensory attributes. The study revealed that both microbial coagulants had no significant impact on the physicochemical composition and firmness of the cheeses while slightly affected the free fatty acids. Cheeses made with microbial coagulants displayed higher proteolysis, with MCR and MCC cheeses exhibiting greater levels of water-soluble nitrogen and 12% trichloroacetic acid-soluble nitrogen than CR cheese. MCR and MCC cheeses exhibited more extensive breakdown of αs- and β-caseins, as indicated by the SDS-PAGE electrophoretogram, compared to CR cheese during ripening. As for the proteolytic activity, the microbial coagulant contributed to shaping the free amino acid content, microstructure, and sensory qualities of the cheeses. Notably, MCC cheese outperformed MCR or CR cheeses in terms of free amino acid levels. MCR and MCC cheeses resulted in smooth microstructures with uniform protein networks as observed by microscopy, while CR cheese displayed rough, granular surfaces. With the highest scores for appearance, body, texture, and flavor, MCC cheese demonstrated superior sensory properties compared with MCR and CR cheeses.

Autochthonous cultures to improve the quality of PGI Castellano cheese: Impact on proteolysis, microstructure and texture during ripening

The aim of this research was to find out the effect of different combinations of starter and non-starter cultures on the proteolysis of Castellano cheese during ripening. Four cheese batches were prepared, each containing autochthonous lactobacilli and or Leuconostoc, and were compared with each other and with a control batch, that used only a commercial starter. To achieve this, nitrogen fractions (pH 4.4-soluble nitrogen and 12 % trichloroacetic acid soluble nitrogen, polypeptide nitrogen and casein nitrogen), levels of free amino acids and biogenic amines were assessed. Texture and microstructure of cheeses were also evaluated. Significant differences in nitrogen fractions were observed between batches at different stages of ripening. The free amino acid content increased throughout the cheese ripening process, with a more significant increase occurring after the first 30 days. Cheeses containing non-starter lactic acid bacteria exhibited the highest values at the end of the ripening period. Among the main amino acids, GABA was particularly abundant, especially in three of the cheese batches at the end of ripening. The autochthonous lactic acid bacteria were previously selected as non-producers of biogenic amines and this resulted in the absence of these compounds in the cheeses. Analysis of the microstructure of the cheese reflected the impact of proteolysis. Additionally, the texture profile analysis demonstrated that the cheese's hardness intensified as the ripening period progressed. The inclusion of autochthonous non-starter lactic acid bacteria in Castellano cheese production accelerated the proteolysis process, increasing significantly the free amino acids levels and improving the sensory quality of the cheeses.

Optimization of protein recovery from sewage sludge via controlled and energy-saving ultrasonic-alkali hydrolysis

The abundant protein in excess sludge can be recovered to prepare high value-added products. However, this sustainable treatment method still has large challenges, such as high energy consumption. In this work, the classical batch operation (BO) and semi-batch operation (SBO) modes were adopted and compared for ultrasonic-alkali hydrolysis. The results showed that the reaction time of SBO significantly decreased to half of that of BO with the same efficiency (ca. 70 %), indicating that SBO was much more energy-efficient. Moreover, analysis of the nitrogen solubility index and trichloroacetic acid-soluble nitrogen index demonstrated that the further proteolysis of protein under SBO was limited. Furthermore, the first-order reaction model fitted the hydrolysis data well (R2 ≥ 0.91) for both modes, in which the rate constant of SBO (k = 0.44 min−1) was 2.3 times that of BO. Finally, the properties of both products met the standards of foaming extinguishers.

Determination of the Effect of Garden Cress (Lepidium sativum L.) on the Ripening Parameters of White Cheese

The aim of this study is to reveal the effect of Lepidium sativum L. on the ripening characteristics of White cheese. A control White cheese without garden cress and White cheeses with four different concentrations of garden cress (0.6-1.2-1.8-2.4%) were produced and their dry matter, fat, and protein contents; pH and titratable acidity levels; water-soluble nitrogen (WSN) and trichloroacetic acid-soluble nitrogen (TCA-SN) were determined and electrophoretograms showing α- and β-casein degradation rates were obtained for the storage of 90 days. The addition of garden cress did not affect WSN and TCA-SN values significantly (P>0.05). Both α- and β- casein degradations increased with storage; the latter being relatively less broken down. The degradation levels for α-casein were similar for all cheese types while β-casein was more degraded when garden cress was included in the cheeses. There was no statistically significant difference between cheese samples in terms of sensory properties (P>0.05). The results suggest that garden cress may carry a β-casein specific protease and could be conveyed with White cheese successfully. This study will contribute to the limited knowledge on the utilization of garden cress in food products. Also, the application of garden cress is thought to expand the product variety in the market.

Effect of Fermented Meat and Bone Meal–Soybean Meal Product on Growth Performance in Broilers

In this study, we screen the proteolytic activity of Bacillus species in meat and bone meal (MBM) and investigate the effects of fermented MBM–soybean meal products (FMSMPs) on the growth performance of broilers. In Trial 1, FMSMPs were fermented using four strains—Bacillus siamensis M3 (M3), B. velezensis M5 (M5), B. subtilis M6 (M6), and B. subtilis M20 (M20)—all of which presented more total peptides and higher degrees of hydrolysis (DH) than Bacillus subtilis var. natto N21 (N21). In Trial 2, 280 0-day-old Arbor Acres broilers, with equal numbers of both sexes, were randomly assigned into 5% fish meal (FM), MBM–soybean meal (MSM, as control), and N21, M3, M5, M6, and M20 FMSMP groups. The results demonstrated that the crude protein, total amino acids, alkaline protease, trichloroacetic acid–soluble nitrogen (TCA-SN), TCA-SN/total nitrogen, total peptides, DH, and free-hydroxyproline levels in the M6 group were greater than those in any other group (p < 0.05). Furthermore, the weight gain in the M6 group was superior to that of the FM and MSM groups in 0–21 and 0–35-day-old broilers (p < 0.05). In conclusion, B. subtilis M6 likely efficiently decomposes MSM to improve the protein properties and nutritional value of the product after fermentation. Supplementation with 5% FMSMP may promote weight gain in broilers.

The effects of heat treatment on chemical, biochemical, and microbiological properties of Ezine cheese

In this study, Ezine cheese was manufactured in accordance with different heat treatment norms (at 65 °C for 10, 20 and 30 minutes) and ripened for 180 days. Different heat treatment norms did not affect the chemical composition of the cheeses, while statistically significantly affected the water-soluble nitrogen (WSN) and 12% trichloroacetic acidsoluble nitrogen (TSN-SN) ratios. Although pH and protein were reduced during ripening, titration acidity, moisture, WSN, TCA-SN and amino acid ratio increased. αs1-casein was more hydrolyzed than β-casein during ripening in Ezine cheese. The heat treatment time increased, while the counts of total aerobic mesophilic bacteria and Escherichia coli decreased.

The Impact of the Adjunct Heat-Treated Starter Culture and Lb. helveticus LH-B01 on the Proteolysis and ACE Inhibitory Activity in Dutch-Type Cheese Model during Ripening.

Simple SummaryAdjunct cultures are used in cheesemaking to improve flavour characteristics and accelerating cheese ripening. Different adjunct cultures are capable of producing enzymes with the specificity to hydrolyze caseins, leading to the release of various bioactive compounds. We studied the effect of adjunct heat-treated starter XT–312 and a cheese culture Lb. helveticus LH-B01 on selected physicochemical, microbiological properties, and on proteolysis in cheese models. Additionally, the effect of adjunct cultures on ACE inhibitory activity during ripening was determined. The application of adjunct cultures may be used as functional ingredients in Dutch-type cheese to maintain sufficient bioactive properties and improve proteolysis.Adjunct cultures are used in cheesemaking to improve the sensory characteristics of the ripened cheeses. In addition, it is known that different adjunct cultures are capable of producing enzymes with the specificity to hydrolyze caseins, leading to the release of various bioactive compounds (bioactive peptides, amino acids, etc.). The objective of this study was to evaluate the effect of adjunct heat-treated starter XT–312 and a cheese culture Lb. helveticus LH-B01 on the proteolytic activity and angiotensin converting enzymes inhibitors (ACE) in cheese models during ripening. Seven different cheese models were evaluated for: proteolytic activity using the spectrophotometric method with ortho-phthaldialdehyde (OPA), soluble nitrogen (SN), trichloroacetic acid-soluble nitrogen (TCA-SN) phosphotungstic acid-soluble nitrogen (PTA-SN), total nitrogen (TN), pH, contents of water, fat, as well as for total bacteria count (TBC), count of Lactococcus genus bacteria, count of Lb. helveticus, and number of non-starter lactic acid bacteria (NSLAB). Presence of adjunct bacterial cultures both in the form of a cheese culture LH-B01 and heat-treated XT–312 starter promoted primary and secondary proteolysis, which resulted in acceleration of the ripening process. ACE inhibitory activity and proteolytic activity was the highest throughout of ripening for cheese model with LH-B01 culture. The cheese models with the adjunct heat-treated starter were characterized by lower TBC, NSLAB and lower count of Lactococcus genus bacteria during ripening, compared to control cheeses.

Proteolysis characteristics and aroma development during ripening of functional IranianLighvancheese

Probiotic Lighvan cheese was studied during 60 days of ripening to determine microbial analysis, proteolysis characteristics, and aroma development. Viability of Bifidobacterium lactis subsp. animalis, water-soluble nitrogen (WSN), total nitrogen (TN), ripening index (RI), trichloroacetic acid-soluble nitrogen (TCA-SN), α-and β-galactosidase activities, aroma compounds, and organoleptic assessments were analyzed. After 60 days of ripening, the survival of B. lactis subsp. animalis was 6.84 log cfu/g. Values for RI and TCA-SN increased continuously throughout ripening. α-and β-galactosidase activities were markedly more pronounced in the present of B. lactis. The final concentration of volatile compounds in probiotic Lighvan cheeses was higher than traditional Lighvan cheese. Among volatile compounds, acetic acid, ethanol, and acetoin were present in the greatest quantities. B. lactis subsp. animalis did not influence sensory characteristics of cheese samples. Novelty impact statement Bifidobacterium lactis affected the proteolysis characteristics of the traditional Lighvan cheese samples; it did not alter the sensory properties of the probiotic samples. At the end of ripening, the cheeses to which bifidobacteria had been added contained significantly (p < 0.05) higher α-and β-galactosidase activity than traditionally produced Lighvan cheese. Most of the volatile compounds identified were present in all cheese samples throughout ripening, with their amounts changing significantly (p < 0.05) as ripening progressed; the final concentration of volatile compounds in most of the probiotic Lighvan cheese samples was higher than in the traditional Lighvan cheese. ​

DETERMINATION OF THE FACTORS THAT CAUSE BITTERNESS DURING SHELF-LIFE IN WHITE CHEESE PRODUCED USING ULTRAFILTRATED MILK

This study aimed to determine the causes of bitterness problems in white cheese produced by ultrafiltration (UF). To investigate the association between the bitterness with the enzyme use or by the starter culture, white cheese was produced using UF-pasteurized and UF-raw milk with two different coagulating enzymes and two starter cultures with different proteolytic activities. Sensory analysis, protein, water-soluble nitrogen, 12% trichloroacetic acid-soluble nitrogen, 5% phosphotungstic acid-soluble nitrogen and acid degree values were determined on day 1, 30, 60 and 90 of the ripening periods. During the ripening process, bitterness was determined in the cheese samples due to proteolysis. The A cheese sample, which was produced using chymosin enzyme and a starter culture with high proteolytic activity, was determined to be the sample with the highest bitterness level in the sensory analyses, SDS-PAGE electrophoresis and HPLC analysis. 72.26% αs-casein hydrolysis was determined in the A cheese sample. According to HPLC results, a high hydrophobic peptide formation was determined with the increase in the area of hydrophobic peptides with a rate of 106% between 40 and 60 minutes.

Sodyum Kazeinat veya Kitosan Bazlı Yenilebilir Kaplamaların Kaşar Peynirnin Bazı Kimyasal, Yapısal ve Mikrobiyolojik, Özelliklerine Etkisi

This study aimed to evaluate the effects of the edible coatings produced from casein, casein / transglutaminase enzyme, and chitosan on certain chemical, textural, and microbiological properties of Kashar cheese over a storage period of 60 days. The use of edible coatings affected the levels of nitrogen fractions (water-soluble nitrogen, trichloroacetic acid-soluble nitrogen, and phosphotungstic acid-soluble nitrogen) and the lipolysis level of Kashar cheese to a statistically significant extent (P&amp;lt;0.05 for all). The levels of nitrogen fractions and lipolysis in the uncoated control group cheeses increased significantly (P&amp;lt;0.05) during the storage period compared to coated cheese. Cheese samples coated with chitosan yielded significantly lower yeast-mould counts compared to samples that were uncoated or coated with sodium caseinate or sodium caseinate/transglutaminase at the end of the storage period (P&amp;lt;0.05). The results indicated that the edible coatings had a significant effect on the chemical, textural, and microbiological properties of Kashar cheese.

Effects of different starter culture applications pre- and post-scalding on the biochemical and sensory properties of pasta filata type cheeses

In this study, three different types of starter cultures (S1, S2, and S3) were applied either before (A1) or after (A2) scalding stage in Tel Cheese production and their chemical, biochemical, electrophoretic, and sensory properties were investigated during ripening. In general, there was no significant difference between the dry matter, fat, protein and salt values of the cheese samples (P > 0.05). However, there were significant differences between the pH and titration acidity values of the samples (P < 0.05). Especially the titration acidity values of cheeses in the A2 application increased significantly until maturity. The WSN (water-soluble nitrogen), TCA-SN (trichloroacetic acid-soluble nitrogen) and PTA-SN (phosphotungstic acid-soluble nitrogen) values were significantly affected by ripening period and increased continuously (P < 0.05). These values for A2S2 and A2S3 cheeses increased more than the others suggesting better ripening characteristics. Electrophoretograms indicated that αs1-and β-casein degradation rates were the highest in A2S2 cheese. Finally, sensory scores of A1 cheeses were found to be higher than those of the A2 cheeses.

Proteolysis, lipolysis, texture and sensory properties of cheese ripened by Monascus fumeus

Monascus spp. are fungi that have been applied in food production for centuries and produce a range of bioactive metabolites. The objective of this study was to investigate the characteristics of proteolysis, lipolysis, textural and sensory properties of internal mold-ripened cheese ripened by Monascus fumeus x08. The contents of pH 4.6-soluble nitrogen, 12% trichloroacetic acid-soluble nitrogen and 5% phosphotungstic acid-soluble nitrogen changed significantly during the ripening of the Monascus-ripened cheese. The peptides in the Monascus-ripened cheese were evaluated by sodium dodecyl sulfate–polyacrylamide gel electrophoresis and reversed-phase high-performance liquid chromatography. During ripening, many low-molecular-weight peptides (MW < 14400) were found to increase significantly and the ratio of hydrophobic to hydrophilic peptides decreased to 0.81 and 0.34 in the Red-O (outer) and Red-I (interior) parts of the cheese, respectively. The content of total free fatty acids (15 acids, C4:0–C18:3) was significantly increased and the content of unsaturated fatty acids reached 47.89 mg/g fat on day 42 of ripening. The sensory attributes of the Monascus-ripened cheese was assessed using quantitative descriptive analysis. Compared with blue cheese, purchased from a local market, the odor and taste intensity of the Monascus-ripened cheese were significantly lower, while the color intensity and overall receptivity were significantly higher. M. fumeus x08 can be used as a secondary starter to make Monascus-ripened cheese and may be particularly acceptable to consumers in China.

GELENEKSEL YÖNTEMLE ÜRETİLEN OTLU PEYNİRLERİN BAZI KALİTE ÖZELLİKLERİNİN VE BİYOAKTİVİTESİNİN BELİRLENMESİ

Bu çalışmada, Van ilinde yerel üreticilerden temin edilen salamura ve basma yöntemleriyle olgunlaştırılmış Otlu peynirlerin kimyasal içeriği ve bu peynirlerin suda çözünür ekstraktlarının biyokimyasal özellikleri, toplam fenolik madde (TFM) içeriği, antioksidan ve antimikrobiyal aktiviteleri tespit edilmiştir. Salamura yöntemiyle olgunlaştırılmış 15 adet Otlu peynirde ortalama suda çözünen azot (SÇN) %16.11±3.72, %12 trikloroasetik asitte (TCA) çözünen azot %13.05±6.20, %5 fosfotungustik asitte (PTA) çözünen azot %7.93±2.75, lipoliz 13.39±6.11 ADV, toplam fenolik madde 647.72±259.80 mg gallik asit eşdeğeri (GAE)/kg, 2,2-difenil-1-pikrilhidrazil (DPPH) inhibisyonu %6.58±2.36 ve troloks eşdeğeri antioksidan kapasite (TEAK) 1.51±0.51 mmol troloks eşdeğeri (TE)/g olarak bulunmuştur. Basma yöntemiyle olgunlaştırılmış 15 adet Otlu peynirde SÇN %16.48±3.98, %12 TCA’ da çözünen azot %17.34.±3.31, %5 PTA’ da çözünen azot %8.40±4.12, lipoliz 9.81±5.58 ADV, TFM 742.81±110.60 mg GAE/kg, DPPH inhibisyonu %8.35±2.31 ve TEAK 1.62±0.56 mmol TE/g olarak saptanmıştır. Ayrıca Otlu peynir ekstraktlarının Staphylococcus aureus ATCC 29213 ve Escherichia coli ATCC 11303’e karşı antimikrobiyal aktivite göstermediği tespit edilmiştir.

The effect of partially or totally replacing milk fat by jojoba oil in Domiati cheese production on some nutritional and quality properties

PurposeThe purpose of this study is to evaluate the effects of partial or total substitution of milk fat by various levels of jojoba oil on the nutritional, physicochemical and sensory properties of Domiati cheese during cold storage at 6°C for 45 days.Design/methodology/approachThe fat percentage of milk used for cheese manufacture was standardized to 4% fat. Five formulas were produced by replacing milk fat with 0%, 25%, 50%, 75% and 100% of jojoba oil, respectively. The physicochemical and sensory properties of cheese samples at 0, 15, 30 and 45th days of cold store were evaluated.FindingsNo significant differences in moisture, fat, protein and acidity values amongst the control samples and those samples supplemented with different concentrations of jojoba oil. Significant differences (p = 0.05) in total volatile fatty acids were detected amongst experimental cheese samples. The highest values were recorded for control sample containing 100% milk fat, while the lowest values were recorded for cheese sample containing 100% jojoba oil (p = 0.05). Total nitrogen (TN), water-soluble nitrogen (WSN) and trichloroacetic acid soluble nitrogen (TCA-SN) levels of experimental cheeses were nearly same as for control. The results of fatty acids profile showed that jojoba oil has a unique structure of straight monounsaturated alcohols. Significantly (p = 0.05), the highest cholesterol content was recorded for control sample containing 100% milk fat; however, the lowest (p = 0.05) value was recorded for cheese sample containing 100% jojoba oil. At the end time of storage period, control sample manufactured with 100% milk fat had the highest (p = 0.05) values of free fatty acids, peroxide and thiobarbituric acid, while the lowest values were recorded for cheese sample with 100% jojoba oil as a source of fat. The sensory evaluation results demonstrated that blending milk fat with jojoba oil improved the sensory properties of Domiati cheese.Practical implicationsIt is concluded that substitution of 25%, 50%, 75% and 100% of milk fat by equal amounts of jojoba oil enhanced the nutritional and sensory characteristics of Domiati cheese.Originality/valueIt is concluded that Domiati cheese formulated with substitution of 25%, 50%, 75% and 100% of milk fat by equal amounts of jojoba oil enhanced the nutritional characteristics and improved the sensory properties of produced cheese.

Evaluation of the Quality Characteristics of Siirt Herby Cheese: A Traditional Turkish Variety

Herby cheese produced in the Province of Siirt is one of the Turkish cheese varieties. The special parameters applied during the production stages give Siirt Herby cheese unique taste properties. The proteolytic, lipolytic, and electrophoretic parameters of Siirt Herby cheese samples were evaluated. The mean values of water-soluble nitrogen, trichloroacetic acid-soluble nitrogen, and phosphotungstic acid-soluble nitrogen of Siirt Herby cheese samples were 9.49±2.66%, 6.33±2.39%, and 1.48±0.71%, respectively. The mean values of free amino group and lipolysis levels were established as 61.97±30.84 mM glycine, and 6.00±2.32 ADV, respectively. The electrophoretic analysis showed that sheep milk was more preferable for Siirt Herby cheese production.

Low Protein Digestibility of Beef Puree in Infant In Vitro Digestion Model.

This study investigated protein digestibility of beef puree in infant and adult in vitro digestion models. The simulated digestive juices for infant and adult were prepared. Protein digestibility of beef puree was calculated in the gastric and gastrointestinal compartments. The 10% trichloroacetic acid soluble nitrogen and α-amino group contents of gastric digesta were lower in the infant in vitro digestion model than those in the adult in vitro digestion model (p<0.05). In addition, the gastrointestinal digesta from the infant in vitro digestion model had lower value of the 10% trichloroacetic acid soluble nitrogen and α-amino group contents than those of the adult in vitro digestion model (p<0.05). The results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the remarkable bands of actin and myosin light chain B were found in the digesta of beef puree from the infant in vitro digestion model. The results of this study revealed the lower protein digestibility of beef puree in infants compared to that in adults. Therefore, the development of ways to increase digestibility of meat protein can improve the nutritional quality of meat products for infants.

Proteolytic Activity of Lactobacillus plantarum Strains in Cheddar Cheese as Adjunct Cultures

Microbial enzymes within adjunct cultures are important for cheese ripening. Here, survival and proteolytic function of adjunct cultures of Lactobacillus plantarum strains MU12 and S6-4 on Cheddar cheese ripening were studied. Cheeses were ripened at 4°C, and samples were collected for analysis after 1, 30, 60, and 90 days. Lactococci numbers decreased by 2 to 3 log versus control, except in a few samples exhibiting significantly elevated numbers. Lactobacilli mainly originated from adjunct cultures, with lactobacilli numbers in adjunct-treated cheese significantly exceeding control numbers after day 30. Postripening, no significant differences were observed in composition (fat, protein, and moisture) and texture among cheeses, although observed significant differences in small nitrogen-containing compound levels (water-soluble nitrogen, trichloroacetic acid-soluble nitrogen, and phosphotungstic acid-soluble nitrogen) reflected proteolytic differences during ripening. Hydrolyzed protein, free amino acids, and volatile levels were consistently higher in adjunct-treated versus control cheeses and affected flavor. Cheddar cheeses may serve to effectively deliver beneficial organisms possessing proteolytic function.

Effects of partial substitution of goat's milk for sheep's milk, cured scalding and dry salting on proteolysis in Urfa cheese

The effects of partial substitution of goat's milk for sheep's milk, scalding and dry salting on the proteolysis of Urfa cheese were monitored for 240 days. For this reason, the contents of total nitrogen, water-soluble nitrogen (WSN), and trichloroacetic acid-soluble nitrogen (TCA-SN) were explored as well as the chemical compositions of samples during ripening. Also, RP-HPLC of pH 4.6-soluble, 70% ethanol-insoluble (EtOH-i), and urea-PAGE of pH 4.6-insoluble nitrogen fractions of samples was determined. The results showed that the effects of partial substitution of goat's milk for sheep's milk on WSN and TCA-SN were significant from sixth to eighth month of the ripening, respectively. Even though the effects of the milk type, dry salting, and scalding on the peptide profile were significant at the beginning of maturation, the peptide profile of cheeses was almost similar at the end of the storage. Furthermore, the proteolysis of Urfa cheese was limited due to dry salting during the ripening. Practical applications The maturation of cheese is a complex biochemical process involving the hydrolysis of fat, breakdown of protein, and metabolism of lactose. Though the biochemical reactions during cheese ripening are not precisely understood, proteolysis is one of the most significant biochemical processes during maturation. It is known that the amino acids resulting from proteolysis are the precursors of flavor components in cheese. Milk itself is a significant source of proteolytic enzymes. And also, the curd scalding temperature and salt content of cheese affect the proteolytic activity during cheese ripening. However, limited proteolysis may be occurred during the cheese maturation due to dry salting and scalding process. Therefore, studies should focus on overcoming this problem. This study can help to overcome the limited proteolysis in the production of cheese. Also, results from the study may contribute to the industrial production of Urfa cheese.

Proteolysis of Reduced-Salt Cheddar Cheese as Affected by Casein to Fat Ratio, Rennet, and pH at Drainage

Effects of change in pH at drainage (6.2, 5.9, and 5.6), rennet concentration (0.1 and 0.3 mL rennet/L of milk) and casein to fat ratio (0.6, 0.7, and 0.8) on proteolytic characteristics of salt-reduced Cheddar cheese were investigated. Chemical composition, lactic acid bacteria and proteolysis were measured. At the same drainage pH, cheeses with C/F ratio 0.6 had significantly higher moisture and ash content compared other ratios. The pH decreased significantly from day 0 (right after pressing) to 120 day and then remained constant. Total LAB growth in cheeses made with 0.3 ml rennet /L was higher at the same C/F ratio and pH at drainage of 6.2. Total plate count at day 180 was significantly higher compared with day 0 (right after pressing). At the same drainage pH, C/F ratio and storage time, water soluble nitrogen contents in cheeses made with 0.3 ml/L rennet were higher compared with 0.1 ml/L. Total free amino acids and trichloroacetic acid-soluble nitrogen contents increased significantly during storage. More hydrophobic peaks appeared as the rennet concentration was increased from 0.1 to 0.3 ml/L. Extra-hydrophobic peptides % in cheese at day 0 and pH at drainage of 5.6, were higher compared to cheese where pH at drainage was 6.2. Increase in C/F ratio and rennet concentration, especially at low pH, showed similar proteolysis as cheese containing 2.5-3% salt.

Multiparametric analysis of cheese using single spectrum of laser-induced breakdown spectroscopy

The potential of using laser-induced breakdown spectroscopy (LIBS) for prediction of chemical quality/control parameters in a cheese matrix was investigated. Traditional methods are usually time-consuming and require complex pre-treatments, the use of toxic chemicals and laboratories and personnel equipped with these analytical skills. In this study, 11 different chemical analyses commonly performed on cheese samples were conducted using traditional methods on 82 full-fat, white pickled and ripened cheese samples. Additionally, these parameters of interest were correlated with multi-elemental spectra of LIBS using partial least squares regression. The results obtained for moisture, dry matter, salt, total ash, total protein, pH, fat, acidity, water soluble nitrogen, trichloroacetic acid soluble nitrogen, and phosphotungstic acid soluble nitrogen (Rcal2 = 0.964, 0.959, 0.970, 0.973, 0.952, 0.971, 0.733, 0.762, 0.714, 0.633, and 0.707, respectively) indicated that LIBS could be used as an alternative or complementary method in quality control of cheese.