Glycolysis, lipolysis and proteolysis in raw sheep milk Tulum cheese during production and ripening: Effect of ripening materials

Postmortem protein phosphorylation in garlic-treated meat during refrigerated storage: Glycolytic and proteolytic changes

The effects of sarcoplasmic and myofibrillar protein phosphorylation on meat quality were studied, focusing on the influence of garlic. Postmortem protein phosphorylation, glycolytic and proteolytic changes were investigated in ground meat with 0 % (control), 1 %, and 2 % garlic during 4 days of refrigerated storage. Twenty sarcoplasmic (S) protein bands were detected using SDS-PAGE. With an increased garlic ratio significantly reducing total phosphorylation (P < 0.05), especially at 48 h postmortem, and the phosphorylation increased in bands S6, S13 and S17, decreased in bands S1, S16, S18, S19 (P < 0.05). The interaction between garlic ratio and postmortem time significantly (P < 0.05) affected the phosphorylation of S2 and S3 bands. Possibly related to the level of sarcoplasmic protein phosphorylation, increasing garlic ratio slowed glycolysis, resulting in lower lactic acid (P < 0.001) and higher pH values (P < 0.01). Additionally, the contents of glycolytic intermediates, including glucose, acetic, pyruvic, citric and succinic acids, were significantly (P < 0.05) higher in control meat compared to garlic-treated ones. For myofibrillar proteins, 14 bands were detected, and phosphorylation of bands M10 and M11 decreased (P < 0.05) with increasing garlic ratio. The phosphorylation of M5 band was significantly (P < 0.05) affected by the interaction between garlic ratio and storage time. Garlic-treated meats were more tender (P < 0.01), possibly due to myofibrillar proteins with decreased phosphorylation, and had higher levels of Lys, Ser + Asn, Tyr amino acids (P < 0.01). The study revealed that protein phosphorylation, influenced by garlic incorporation, might play a critical role in regulation meat quality, likely through its effects on glycolysis and proteolysis.

Characterization of a traditional ripened cheese, Kurdish Kope cheese: Proteolysis, microstructural, and rheological characteristics

This study explored the primary and secondary proteolysis reactions in Kope cheese made from raw sheep milk, revealing significant biochemical and structural changes throughout the ripening process. The ripening index and proteolysis depth increased significantly (p < 0.05) during the ripening period. Electrophoresis results indicated that by the end of ripening, 44.7% of αs1-casein and 70.2% of β-casein residues remained intact, reflecting progressive protein breakdown. The low-molecular-weight protein-to-casein ratio rose from 0.12 to 0.40, signifying intensified proteolysis over time. Analysis of the ethanol-soluble fraction's peptide profile showed two prominent peaks between 40 and 50 min and a single major peak between 20 and 25 min, demonstrating the formation of specific peptides during maturation. Free amino acid analysis revealed higher concentrations of glutamic acid, leucine, and lysine in Kope cheese, signifying a rich profile of flavor-enhancing compounds. Principal component analysis classified the cheeses into three distinct ripening categories: (1) Young-ripened cheese (37-67 days) with low proteolysis intensity; (2) Mild-ripened cheese aged 67-127 days, characterized by the lowest mean storage modulus (G') value (576 KPa); (3) Old-ripened cheese (127-187 days) displaying significant proteolysis intensity and a comparatively low G' value. Scanning Electron Microscopy (SEM) imaging revealed dramatic structural changes during ripening. Initially, the cheese had a compact and rough texture, which evolved into an open, crumbly structure by the end of the ripening period. These changes corresponded with the biochemical processes of proteolysis and the resulting textural softening.

Application of whole genome sequenced selected Pediococcus acidilactici to tailor the making of the spreadable fresh ewe's milk "Quadrello di Ovino" cheese to the production area

The aim of this study was to utilize Pediococcus acidilactici strains as starter microorganisms in producing the fresh ewe's cheese "Quadrello di Ovino". Whole-genome analysis confirmed the absence of virulence factors (such as hemolysins) and genes conferring resistance to commonly used antibiotics indicated by the European Food Safety Authority. A control trial was conducted with commercial freeze-dried starters (CP), against the novel experimental cheese (EXP) inoculated with pediococci. Cheeses from both the control and experimental production showed high levels of lactic acid bacteria (LAB). Mesophilic LAB were present at 7.09 and 8.50 log CFU/g, respectively, while thermophilic LAB were found at 6.95 and 8.46 log CFU/g, respectively. Both cheeses showed no presence of spoilage or pathogenic microorganisms according to plate counts. While there were no significant differences in fat and protein content between them, the EXP cheese had a slightly higher protein content (16.85 %). Additionally, both cheeses had a complex profile of volatile organic compounds, with higher monounsaturated fatty acids (oleic acid) and polyunsaturated fatty acids (linoleic and linolenic acids) content in the EXP cheese at 26.80 %, 2.61 %, and 0.70 %, respectively. From a sensory perspective, the EXP cheese showed a diminished persistence of the taste typical of ewe's milk and a reduction in the unpleasant animal odour commonly found in cheeses made from small ruminants, while enhancing paste homogeneity and odor intensity. These observations indicate the product's promising potential, considering the increasing demand in local and foreign markets for spreadable cheeses with creamy consistence.

Quantification of Bioactive Metabolites Derived from Cell-Free Supernatant of Pediococcus acidilactici and Screening their Protective Properties in Frankfurters

The specific aims of the current study were to determine and quantify the bioactive compounds derived from the cell-free supernatant (CFS) of Pediococcus acidilactici and screen their protective effect in frankfurters by applying an edible coating. This was achieved by immersing the peeled frankfurters in the CFS (CFS: 50% and 100%) alone or in combination with chitosan (CH: 0.5% and 1%) solutions for 3 min. Untreated frankfurter samples (control) exceeded the maximum acceptable total viable count limit (7.0 log10) on the 14th day, whereas samples treated with 100% CFS + 1% chitosan reached the limit on day 28 during refrigerated storage (P < 0.05). This treatment provided a 14-day extension to the shelf life of frankfurters without causing any significant changes in color and sensory attributes (P > 0.05). Additionally, this treatment inhibited oxidation in the frankfurters, leading to no significant changes in TBA and TVB-N within this group during storage (P > 0.05). This protective effect was mainly attributed to the wide variety of bioactive compounds identified in the CFS, including a total of 5 organic acids, 20 free amino acids, 11 free fatty acids, 77 volatiles, and 10 polyphenols. Due to these bioactive compounds, CFS exhibited a strong radical scavenging capacity (DPPH: 435.08 TEAC/L, ABTS: 75.01 ± 0.14 mg TEAC/L; FRAP: 1.30 ± 0.03 mM FE/L) and antimicrobial activity against microorganisms primarily responsible for the spoilage of frankfurters. In conclusion, the results indicate that the CFS contains high levels of bioactive metabolites, and an edible chitosan coating impregnated with CFS can be utilized to extend the shelf life of frankfurters through its antimicrobial effects and oxidation stabilization.

Interference of endogenous benzoic acid with the signatures of sulfonic acid derivatives and carbohydrates in fermented dairy products

Endogenous benzoic acid causes detrimental effects on public health, but the underlying mechanisms often remain elusive. Benzoic acid (0.00-40.00 mg L -1) was detected from sixty fermented goat milk samples in six replicates, indicating the existence of endogenous benzoic acid. Herein, we investigated the effects of benzoic acid on the variations of metabolome and proteome signatures in fermented goat milk via integrative metabolomics (LOQ 2.39-98.98 μg L -1) and proteomics approach based on UHPLC-Q-Orbitrap HRMS. Explicitly, benzoic acid reduced the content of taurine (7.06-4.80 mg L -1) and hypotaurine (3.86-1.74 mg L -1) due to a significant decrease in the levels of glutamate decarboxylase 1 by benzoic acid. The reduction in lactose (7.13-5.31 mg L -1) and d-galactose (4.39-3.37 mg L -1) content was related to the decrease in α-lactalbumin and β-galactosidase levels, respectively, in fermented goat milk containing 40.00 mg L -1 benzoic acid. Meanwhile, the levels of maltose (22.84-16.53 mg L -1) and raffinose (4.19-3.10 mg L -1) progressively decreased with increasing benzoic acid concentrations (0.00-40.00 mg L -1), which had detrimental effects on the nutritional quality of fermented goat milk. Additionally, the concentration of benzoic acid and fermentation temperature are the most important factors to control the loss of nutrients in fermented dairy products.

Metabolomic profiling of Fiore Sardo cheese: Investigation of the influence of thermal treatment and ripening time using univariate and multivariate classification techniques

The effect of different sub-pasteurization heat treatments and different ripening times was investigated in this work. The metabolite profiles of 95 cheese samples were analyzed using GC-MS in order to determine the effects of thermal treatment (raw milk, 57 °C and 68 °C milk thermization) and ripening time (105 and 180 days). ANOVA test on GC-MS peaks complemented with false discovery rate correction was employed to identify the compounds whose levels significantly varied over different ripening times and thermal treatments. The univariate t-test classifier and Partial Least Square Discriminant Analysis (PLS-DA) provided acceptable classification results, with an overall accuracy in cross-validation of 76% for the univariate model and 72% from the PLS-DA. The metabolites that mostly changed with ripening time were amino acids and one endocannabinoid (i.e., arachidonoyl amide), while compounds belonging to the classes of biogenic amines and saccharides resulted in being strongly affected by the thermization process.

Analysis of the effect of Tenebrio Molitor rennet on the flavor formation of Cheddar cheese during ripening based on gas chromatography-ion mobility spectrometry (GC-IMS)

This study aimed to evaluate the potential application of Tenebrio Molitor rennet (TMR) in Cheddar cheese production, and to use gas chromatography-ion mobility spectrometry (GC-IMS) to monitor flavor compounds and fingerprints of cheese during ripening. The results indicated that Cheddar cheese prepared from TMR (T_F) has fat content significantly lower than that of commercial rennet (C_F) (p < 0.05). However, the results of the sensory evaluation showed that there were no statistically significant differences between the two kinds of cheese (p > 0.05). Both cheeses were rich in free amino acids and free fatty acids. Compared to the C_F cheese, gamma-aminobutyric acid and Ornithine contents of the T_F cheese reached 187 and 749 mg/kg, respectively, during 120 days of ripening. Moreover, GC-IMS provided information on the characteristics of 40 flavor substances (monomers and dimers) in the T_F cheese during ripening. Only 30 flavor substances were identified in the C_F cheese. The fingerprint of the two kinds of cheese during ripening can be established by GC-IMS and principal component analysis based on the identified flavor compounds. Therefore, TMR has potential application in Cheddar cheese production. GC-IMS might be applied for the quick, accurate and comprehensive monitoring of cheese flavor during ripening.

What happens to commercial camembert cheese under packaging? Unveiling biochemical changes by untargeted and targeted metabolomic approaches

Camembert cheese undergoes various biochemical changes during ripening, which lead to its unique aroma and typical flavor characteristics. This study aimed to systemically evaluate the primary biochemical events (lipolysis and proteolysis) and secondary metabolites (flavor compounds) of commercial Camembert during 56 days of ripening under packaging conditions. The changes of free fatty acid, free amino acids, soluble nitrogen, proteins/peptides distribution, odorant contribution, and volatile profiles were studied. Results showed that the lipolytic process was prevalent during the initial 14 days, while the proteolysis level continuously increased as the ripening period advanced, causing the index of ripening depth to increase from 4.8% to 13.9%. On day 28, the sample developed odorants with high modified frequency values of 94.3%. With the untargeted metabolomic approaches, two major (γ-butyrolactone and methyl heptenone) and four minor (3-methyl-1-butanol, γ-hexalactone, 2-nonanone, and dodecanoic acid) volatile markers were recognized to discriminate the ripening stages of Camembert cheese.

Key aroma compounds of Canastra cheese: HS-SPME optimization assisted by olfactometry and chemometrics

An analytical method was developed to determine volatile compounds (VC) that contribute to the aroma of cheese from Serra da Canastra (Brazil) and evaluate them in three ripening stages (fresh, short-ripened, and ripened) via headspace solid-phase microextraction (HS-SPME) combined with gas chromatography (GC). Proximate and fatty acid compositions were determined to observe whether there would be changes during ripening. Multivariate designs were applied to optimize the extraction parameters of volatile compounds and assisted by GC olfactometry (GC-O) and chemometrics. The adopted strategy revealed that the best extraction condition requires 10 min of equilibration, 75.2 min of fiber exposure at 40 °C, and 1 g of sample. The data obtained evidenced the alteration of the abundance of volatile compounds, fatty acids, and proximate composition of Canastra cheese during ripening. The fatty acid profile of the samples was mainly composed of palmitic, oleic, and stearic acids. This dairy product is rich in volatile compounds and formed primarily by alcohols (n = 14), acids (n = 13), and esters (n = 11). Olfactometry indicated that the VCs that most affected the aroma of ripened Canastra cheese were acetic acid, isobutyric acid, butanoic acid, and ethyl hexanoate. The method developed effectively discriminated against Canastra cheeses at their different ripening stages.

Characterization of a traditional ripened cheese, Kurdish Kope: Lipolysis, lactate metabolism, the release profile of volatile compounds, and correlations with sensory characteristics

Kope cheese has been characterized based on gross chemical composition, free fatty acids (FFAs), organic acids (OAs), volatile compounds (VCs), and sensory attributes (SAs) during 187 days of the ripening period. C16:0, C18:1cisΔ9, and C14:0 were the most abundant FFAs. Lactic and acetic acids were the most prevalent OAs affecting sensory properties. principal component analysis (PCA) indicated that butanoic acid, butyl hexanoate, and 2,3-butanediol were as key VCs. Protein contents, pH (based on FFA and OA), salt in the moisture (S/M), and water activity (a_w ) (based on VC and SA) were highly correlated with PC2, resulted in two distinct groups. Based on lipolysis and glycolysis studies, early-ripened cheese samples showed lipolysis and lactate metabolism more intensely compared to medium and old-ripened ones. Based on the data of VC and SA, the samples may be classified into three groups: (1) early-ripened cheeses with a salty taste, waxy to cheesy odor, and rubbery texture, (2) medium-ripened cheese with a sweet taste and cheesy odor, and (3) old-ripened cheese with a bitter taste, cheesy to pungent odor, a firm and fragile texture. Textural attributes were highly correlated with proteolysis indices and pH. The results of sensory desirability indicated a significant correlation with pungency, bitterness, and OAs. The cheese samples ripened on the day 127 were selected as the most desirable product. Ripening time had a significant effect on the chemical composition, especially on S/M, pH, and a_w  parameters, which determine the pattern as well as the intensity of biochemical pathways and the final sensory attributes. PRACTICAL APPLICATION: The current study intends to characterize and develop a standardized procedure for producing a traditional cheese called "Kope cheese" by determining the appropriate duration time for the ripening process, determining the main chemical/biochemical compounds that are highly correlated with its unique flavor and texture and distinguishing the key processing factors (such as curd salting, pH values during brining) that have to be altered or controlled carefully during the manufacturing process. The data would help cheese manufacturers determine the optimum time of ripening in order to achieve the best flavor and texture attributes in the final product.

The effects of packaging materials on the fatty acid composition, organic acid content, and texture profiles of Tulum cheese

In this research, Erzincan Tulum cheese was packaged in its original packaging material, the skin bag, small intestine, and appendix to observe the changes in its physical, chemical, and textural properties during storage day. Lactic acid% values increased in all Tulum cheeses throughout storage stage. At the end of the storage period, the highest value was determined in the sample filled in the small intestine (20.10%). All fatty acid values were increased, and the highest increase was identified in oleic acid (C 18:1) (skin bag 2.18%), linoleic acid (18:2) (appendix 0.41%), and palmitic acid (C 16:0) (small intestine 0.34%), respectively. All organic acids increased in stored sample. The highest increase among organic acids was determined to be 4.47% in lactic acid. As a result of the Texture Profile Analyses (TPA), the hardness, and adhesiveness of Tulum cheeses increased during storage periods, whereas the springiness, cohesiveness, and chewiness values decreased. Gumminess value declined in the sample filled into the appendix (with a value of 36.01), whereas it increased in the other two samples. The highest increase in hardness values was 2,520.27 N at given storage time was in the samples filled into appendix while the highest adhesive values of -49.82 were determined in the sample filled into small intestine. PRACTICAL APPLICATION: Tulum cheese is usually produced by filling sheep or goat skin bag. Goat or sheep skin bag are not always available, and the amount of cheese produced in them is excessive. Therefore, cheeses were also filled to small intestine and appendix. At the end of the study, there were no negative effects on cheeses filled with intestine and appendix. The use of small intestine and appendix has helped to develop a product that will be appreciated by the consumers with no adverse effects in the physicochemical and textural properties of cheese.

Cytotoxicity and degradation product identification of thermally treated ceftiofur

Ceftiofur (CEF) is a cephalosporin antibiotic and is a commonly used drug in animal food production. As a heat-labile compound, the residual CEF toxicity after thermal treatment has rarely been reported. This study was to investigate the potential toxicity of thermally treated CEF and determine the toxic components. By cytotoxicity tests and liquid chromatography-mass spectrometry (LC-MS) assays, the cytotoxicity of the thermally treated CEF (TTC) and the components of TTC was identified, respectively. Our results showed that TTC exhibited significantly increased toxicity compared with CEF towards LO2 cells by inducing apoptosis. Through LC-MS assays, we identified that the toxic compound of TTC was CEF-aldehyde (CEF-1). The IC₅₀ value of CEF-1 on LO2 cells treated for 24 h was 573.1 μg mL⁻¹, approximately 5.3 times lower than CEF (3052.0 μg mL⁻¹) and 3.4 times lower than TTC (1967.0 μg mL⁻¹). Moreover, we found that CEF-1 was also present in thermally treated desfuroylceftiofur (DFC), the primary metabolite of CEF, indicating that residual CEF or DFC could produce CEF-1 during the heating process. These findings suggest that CEF-1 is a newly identified toxic compound, and CEF-1 may pose a potential threat to food safety or public health.

Ceftiofur (CEF) is a cephalosporin antibiotic and is a commonly used drug in animal food production. This study investigated the cytotoxicity of thermally treated CEF.

Serra da Estrela cheese's free amino acids profiles by UPLC-DAD-MS/MS and their application for cheese origin assessment

Serra da Estrela cheese is a high-value Portuguese Protected Designation of Origin cheese, produced with raw ewe milk. Thus, information regarding its composition is of utmost relevance for both consumers and certified producers. In this work, the chromatographic profiles of free amino acids in cheeses (45 days of maturation, 6 producers located in 5 municipalities and produced from November 2017 to March 2018) were established by UPLC-DAD-MS/MS. The proposed method allowed detecting 19 free amino acids and cystine with overall limits of detection and quantification lower than 44 μmol/L (1.4 mg/100 g cheese, wet matter) and than 134 μmol/L (4.2 mg/100 g cheese, wet matter), respectively. In all cheeses, 17 free amino acids were quantified including 8 essential amino acids (histidine, leucine-isoleucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine) and 9 non-essential amino acids (arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, proline, serine and tyrosine). The amounts of the free amino acids, essential free amino acids, branched chain free amino acids (leucine, isoleucine and valine) plus the free amino acids ratios (mg/g protein) were further used to identify the producer of Serra da Estrela cheeses. Linear discriminant analysis coupled with the simulated annealing variable selection algorithm was used allowing the correct classification of 96% and 90 ± 8% of the samples, for leave-one-out and repeated K-fold cross-validation procedures, respectively. The satisfactory predictive performance pointed out the possibility of using cheeses' amino acids profiles as origin biomarkers for authenticity control, warranting the correctness identification of the cheese producer/brand, which is quite relevant for ensuring the consumer confidence and satisfaction when purchasing this high-value dairy food.