Changes of free amino acids and biogenic amines during extended ageing of Italian dry-cured ham

Characterization of dry-cured ham microbiota at 12 months of seasoning obtained from different rearing strategies using 16S rRNA profiling

In this study, we investigated the microbiota of 72 Italian ham samples collected after 12 months of seasoning. The hams were elaborated from pigs fed different rearing methods, including the traditional restricted medium protein diet chosen as control (C group); restrictive low protein diet (LP group); two ad libitum high-protein diet groups (HP9M group: slaughter at 9 months of age; HP170 group: slaughter at 170 kg). A multi-amplicon 16S metabarcoding approach was used, and a total of 2845 Amplicon Sequence Variants were obtained from the 72 ham samples. Main phyla included: Firmicutes (90.8%), Actinobacteria (6.2%), Proteobacteria (2.7%), and Bacteroidota (0.12%). The most common genera were Staphylococcus, Tetragenococcus, and Brevibacterium. Shannon index for α-diversity was found statistically significant, notably for the HP9M group, indicating higher diversity compared to C. PERMANOVA test on β-diversity showed significant differences in rearing methods between HP170 and C, HP170 and LP, and HP9M vs. C. All three rearing methods revealed associations with characteristic communities: the HP9M group had the highest number of associations, many of which were due to spoilage bacteria, whereas the LP group had the highest number of seasoning-favourable genera.

Inoculation fermentation with Lactobacillus fermentum L28 and Staphylococcus epidermidis S24 for improving the protein degradation of air-dried goose

The inoculation fermentation technology was applied to the processing of dried cured goose to investigate the protein degradation. Lactobacillus fermentum (L), Staphylococcus epidermidis (S) and mixed strains (L + S) were individually inoculated into the whole goose before drying. We studied the degradation of protein in the air-dried period of goose. The results showed that compared with natural fermentation, inoculation fermentation significantly increased the content of non-protein nitrogen (14.85 mg/g NPN), proteolysis index (8.98% PI), myofibril fragmentation index (89.35 MFI) and total amount of free amino acids (1332.6 mg/g FAA) of dried cured goose. Electrophoresis revealed that the inoculation fermentation accelerated the degradation of macromolecular proteins and the accumulation of small molecular proteins. The degree of protein degradation in four groups of goose was in an order of L + S group > S group > L group > CK group. It suggested that inoculation fermentation could promote the degradation of myofibrillar proteins.

Effect of Overripening on the Physico-Chemical and Sensory Characteristics of Boneless, Salt-Reduced Iberian Dry-Cured Ham

The aim of this study was to evaluate the effect of extended maturation and temperature increase on the physico-chemical, biochemical, instrumental color and texture, sensory, and acceptability parameters of cured and boneless Iberian hams. Given the limited knowledge in this area, our objective was to develop a ham with enhanced proteolysis, potentially leading to increased bioactive peptide generation and superior sensory characteristics compared to salt-reduced counterparts. To achieve this, a batch of hams cured up to 38% loss at 30 °C and two batches cured up to 42% loss at 30 °C and 36 °C were evaluated. Results showed that the increase in processing time and temperature significantly enhanced (p < 0.05) ham proteolysis and amino acid content without adversely affecting its texture. No significant differences were observed in instrumental texture parameters or sensory attributes as evaluated by consumers. These processing conditions also increased the content of free amino acids, improving the product quality. Overall, these processing modifications resulted in hams with excellent sensory acceptability and enhanced bioactive potential despite the salt reduction.

Volatile compounds, gamma-glutamyl-peptides and free amino acids as biomarkers of long-ripened protected designation of origin Coppa Piacentina

Coppa Piacentina is an Italian protected designation of origin (PDO) dry-cured product obtained from the muscle of pork neck and ripened for at least six months. Metabolomics- and volatilomics-based strategies, combined with a chemical characterization of free amino acids were applied to identify biomarkers of long-ripened Coppa Piacentina PDO. Long ripening induced a significantly increase of total free amino acids, mainly represented by glutamic acid, involved in the umami taste perception. Untargeted metabolomics, performed using UHPLC-HRMS, allowed to identify 32 putative gamma-glutamyl-peptides, known as main contributors to the kokumi taste. Unsupervised and supervised multivariate statistics observed a clear modification of these peptides over the ripening, with gamma-glutamyl-peptides which significantly increased in long-ripened samples. A volatilomics-based strategy, conducted with GCxGC-MS, was then performed, and 93 different compounds were identified, with aldehyde and ketones deriving from the lipid auto-oxidation which increased according to ripening.

Flavor profile of "Dao Ban Xiang" (a traditional dry-cured meat product in Chinese Huizhou cuisine) at different processing stages in winter and summer

"Dao Ban Xiang" is a famous traditional Chinese dry-cured meat product. This study aimed to comparatively analyze the difference in the volatile flavor information of "Dao Ban Xiang" produced in winter and summer. In this study, we determine the physical and chemical properties, free amino acids (FAAs), free fatty acids (FFAs), and volatile compounds in the four processing stages of samples in winter and summer. The content of FAAs decreased significantly during the curing period in winter while increasing steadily in summer. The content of total FFAs increased in both winter and summer, and polyunsaturated fatty acids (PUFAs) decreased significantly in summer. The characteristic compound in winter samples is hexanal, nonanal, and (E)-2-octenal, which may mainly come from the degradation of FAAs, while the characteristic compound in winter samples is hexanal, nonanal, and (E)-2-nonenal, which may mainly be derived from the oxidation of FFAs. This study extends our knowledge on flavor from traditional cured meat products at different processing stages in different seasons and could be useful for the standardization of the traditional and regional meat products.

Discovery of specific antioxidant peptide from Chinese Dahe black pig and hybrid pig dry-cured hams based on peptidomics strategy

The quality of hams obtained from different pig breeds can vary depending on endogenous antioxidant peptides in the hams. The aims of this study were (i) to investigate the specific peptides in Chinese Dahe black pig ham (DWH) and hybrid pig ham (Yorkshire × Landrace × Dahe black ham, YLDWH) and their antioxidant activity, and (ii) to elucidate the relationship between ham quality and antioxidant peptides. iTRAQ quantitative peptidomic method was used to discover specific peptides of DWH and YLDWH. In addition, in vitro assays were performed to evaluate their antioxidant activity. A total of 73 specific peptides were identified from DWH and YLDWH by LC-MS/MS. Forty-four specific peptides in DWH were primarily hydrolysed from myosin and myoglobin by endopeptidases, while 29 specific peptides in YLDWH were primarily hydrolysed from myosin and troponin-T. Six specific peptides that were statistically significantly different based on their fold changes and P-values were selected for the identification of DWH and YLDWH. DWH-derived specific peptide AGAPDERGPGPAAR (AR14), which had high stability and was non-toxic, had the highest DPPH• and ABTS•+ scavenging activity (IC₅₀ = 1.657 mg/mL and 0.173 mg/mL, respectively) and cellular antioxidant capacity. Molecular docking showed that AR14 interacted with Val369, and Val420 of Keap1 via hydrogen bonds. Furthermore, AR14 bound to DPPH and ABTS through hydrogen bonding and hydrophobic interactions. Together, our results demonstrate that the DWH-derived antioxidant peptide AR14 exhibits the free radical scavenging and cellular antioxidant activity and can be used to preserve ham quality and promote human health.

Free-Choice Feeding of Whole Grains Improves Meat Quality and Intestinal Development of Pigeon Squabs Compared with Complete Pelleted Feed

Effects of different feeding strategies on meat quality and intestinal development in pigeon squabs were investigated. 120 pairs of pigeons with two squabs each were assigned to five groups (four free-choice feeding systems and one complete feeding system): T1 (corn, pea, wheat, and pelleted feed), T2 (corn, wheat, and pelleted feed), T3 (corn, pea, and pelleted feed), T4 (corn and pelleted feed), and T5 (complete pelleted feed). Compared with T5, the diet in T4 made the breast meat redder and more yellow (p < 0.05). T2 and T4 resulted in an enhanced total superoxide dismutase activity of meat. Breast muscle in T1 and T2 was determined to have higher contents of nonessential amino acids, glycine, alanine, and glutamic acid (p < 0.05). The contents of the essential amino acids, lysine, threonine, valine, histidine, and arginine were also higher in T1 (p < 0.05). Villus height, surface area, and alkaline phosphatase activity of the duodenum and jejunum in T2 were the highest among the treatments (p < 0.05). In conclusion, free-choice feeding system can improve the meat quality and intestinal development of pigeon squabs, but which combination method of whole grains to use in the production depends on the feeding purpose.

Biogenic amines and volatile N-nitrosamines in Chinese smoked-cured bacon (Larou) from industrial and artisanal origins

This study aimed to compare biogenic amines (BAs), volatile N-nitrosamines (VNAs) and chemical properties of Chinese smoked-cured bacon (Larou) from industrial and artisanal sources. The results indicated that nitrite residues were low in artisanal Larou, whereas the salt content was relatively high in all samples. The family-made Larou accumulated high levels of BAs and probably present a health risk. Additionally, phenylethylamine exceeded 30 mg/kg in 4 out of 5 industrial Larou samples, whereas, 9 VNAs concentrations were low and unlikely to induce adverse health effects on consumers. Principal component analysis revealed that the industrial Larou products had similar safety properties in terms of BAs and VNAs content when compared to the family-made samples. Correlation analysis indicated that BAs and VNAs were significantly correlated with free amino acids, a_w, pH and NaCl, respectively. This study suggests that the quality of Larou needs to be further improved by reducing salt and BAs content.

Changes in the Physical-Chemical Properties and Volatile Flavor Components of Dry-Cured Donkey Leg during Processing

In order to explore the quality variation and flavor formation of dry-cured donkey leg, the changes in physical−chemical composition, lipolytic, free amino acids content and volatile flavor compounds were investigated in this study. Six fresh, trimmed hind legs with average weight of 8.12 ± 0.8 kg were taken from male Dezhou donkeys slaughtered at the age of 24 months with the average live weight of 240 kg. The entire processing time was eight months long including six stages, specifically: cooling, salting, air-drying, fermenting and aging. Samples were collected at 0 d, 10 d, 20 d, 30 d, 65 d, 105 d and 165 d of processing. The results showed that the pH value remained stable in the range of 6.2~6.6. The moisture and water activity significantly decreased (p < 0.05) during processing. The chloride content, ash, total volatile basic nitrogen (TVB-N) and peroxide value (POV) significantly increased (p < 0.05), from 0.45% to 12.39%, from 3% to 17%, from 1.43 mg/kg to 8.98 mg/kg and from 1.39 g/100 g to 5.26 g/100 g, respectively. The thiobarbituric acid (TBARS) value reached its highest value of 0.39 mg MDA/kg at the end of the salting stage and then decreased to 0.34 mg MDA/kg. Eighteen free amino acids and fifteen free fatty acids were detected, and their contents were significantly increased during processing (p < 0.05). Volatile compounds were analyzed using solid-phase microextraction (SPME) and gas chromatography−mass spectrometry (GC−MS). Among 114 volatile compounds detected in dry-cured donkey leg, aldehydes, esters, alkane and alcohols were more abundant in the final products, with relative concentrations of 41.88%, 5.72%, 5.35% and 5.25%, respectively. Processing significantly affected the physical−chemical properties, which could contribute to the formation of flavor substances of dry-cured donkey leg.

Isolation and characterization of a salt-tolerant γ-glutamyl transpeptidase from xerophilic Aspergillus sydowii

Xerophilic Aspergillus molds isolated from halo-alkaliphilic and dry environments are attractive genetic resources for obtaining salt- and osmo-adaptive enzymes. A. sydowii MA0196 secreted the largest amount of γ-glutamyl transpeptidase (GGT) during solid-state fermentation at a low initial water activity (a w = 0.85). Gel filtration analysis revealed that the molecular mass of the purified native enzyme (MA0196 GGT) was 120 kDa. SDS-PAGE analysis showed that MA0196 GGT consists of two subunits with molecular masses of 56.4 and 33 kDa, indicating production from a proenzyme via autoproteolysis. Deglycosylation of the subunits by N-glycosidase F yielded 40.9 and 19.6 kDa species. MA0196 GGT retained transpeptidase and hydrolysis activities and their catalytic efficiency (k cat/K m) under high salt and low water activity. The enzyme displayed broad substrate specificity toward γ-glutamyl acceptors such as amino acids and the imidazole dipeptides, carnosine and anserine. Carnosine and L-glutamine were converted into γ-glutamyl-β-alanyl-L-histidine by MA0196 GGT with a 32.9% yield in the presence of 2% (v/v) dimethyl sulfoxide. Phylogenetic analysis indicated that MA0196 GGT forms a distinct lineage from A. oryzae and A. sojae GGTs. These excellent properties indicate that MA0196 GGT can be used in salted fermentation and for producing bioactive peptides.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03259-3.

The Changes Occurring in Proteins during Processing and Storage of Fermented Meat Products and Their Regulation by Lactic Acid Bacteria

Protein, which is the main component of meat, is degraded and oxidized during meat fermentation. During fermentation, macromolecular proteins are degraded into small peptides and free amino acids, and oxidation leads to amino acid side chain modification, molecular crosslinking polymerization, and peptide chain cleavage. At different metabolic levels, these reactions may affect the protein structure and the color, tenderness, flavor, and edible value of fermented meat products. Lactic acid bacteria are currently a research hotspot for application in the fermented meat industry. Its growth metabolism and derivative metabolites formed during the fermentation of meat products regulate protein degradation and oxidation to a certain extent and improve product quality. Therefore, this paper mainly reviews the changes occurring in proteins in fermented meat products and their effects on the quality of the products. Referring to studies on the effects of lactic acid bacteria on protein degradation and oxidation from all over the world, this review aims to provide a relevant reference for improving the quality of fermented meat products.

Mechanism of biogenic amine synthesis of Enterococcus faecium isolated from Sanchun ham

Sanchuan ham, produced in Yunnan, China, is food with ethnic characteristics favored by consumers. However, it can contain biogenic amines such as tyramine that are harmful to health, and the synthesis mechanism of biogenic amines in Sanchuan ham is not clear. This study focuses on the regulation of biogenic amine synthesis by quorum sensing. We used high‐performance liquid chromatography to detect the content of biogenic amine in different kinds of ham and found that the content of biogenic amine in Sanchuan ham was higher than that in others. Tyramine‐producing strain isolated from Sanchuan ham was identified as Enterococcus faecium. By monitoring the growth and tyramine synthesis of Enterococcus faecium under cultured conditions, the results found that high temperature and low salt increased tyramine production by E. faecium. After seven exogenous amino acids were applied to E. faecium, only tyrosine could promote the production of tyramine in E. faecium, and tyramine could not be synthesized in E. faecium until a certain amount was reached, indicating the presence of microbial quorum sensing signal molecules in the synthesis of tyramine in E. faecium. Untargeted metabolomics analysis of the differential metabolites produced by E. faecium showed that the contents of some peptides, especially alanyl‐leucine, were significantly increased. Further experiments with synthetic alanyl‐leucine illustrated that alanyl‐leucine activated the expression of tyrosine decarboxylase (tyrDC), thereby regulating the synthesis of tyramine by E. faecium. Alanyl‐leucine acted as quorum sensing signal molecules for biogenic amine synthesis by E. faecium, which provided a theoretical basis for reducing biogenic amine accumulation in ham. It is beneficial to control the content of biogenic amines in ham in the future.

Recent developments in off-odor formation mechanism and the potential regulation by starter cultures in dry-cured ham

Foul-smelling odors are main quality defects of dry-cured ham, which are connected with the excessive degradation of the structural proteins and excessive oxidation of lipids caused by the abnormal growth of spoilage microorganisms, threatening the development of dry-cured ham industry. Characterizing the key microorganisms and metabolites resulted in the spoilage of dry-cured ham, and discussing the relationship between spoilage microorganisms and metabolites are the key aspects to deeply understand the formation mechanism of off-odor in dry-cured ham. Until now, there is no detailed discussion or critical review on the role of spoilage microorganisms in developing the off-odor of dry-cured ham, and the regulation of off-odor and spoilage microorganisms by starter cultures has been not discussed. This review shows the recent achievement in the off-odor formation mechanism of dry-cured ham, and outlines the potential regulation of off-odor defects in dry-cured ham by starter cultures. Results from current research show that the abnormal growth of Lactic acid bacteria, Micrococcaceae, Enterobacteriaceae, Yeasts and Molds plays a key role in developing the off-odor defects of dry-cured ham, while the key spoilage microorganisms of different type hams are discrepant. High profile of aldehydes, acids, sulfur compounds and biogenic amines are responsible for off-odor development in spoiled dry-cured ham. Several starter cultures derived from these species of Staphylococcus, Penicillium, Debaryomyces, Pediococcus and Lactobacillus show a great potential to prevent microbiological hazards and improve flavor quality of dry-cured ham, whereas, the ecology, function and compatibility of these starter cultures with the processing parameters of dry-cured ham need to be further evaluated in the future.

Biochemical Properties Affecting the Nutritional Quality, Safety, and Aroma of Dry-Cured Products Manufactured from Meat of Rare Native Pig Breeds

The aim of study was to compare the biochemical properties affecting the nutritional quality, safety, and aroma of dry-cured products manufactured from valuable meat of rare native pig breeds: Pulawska (Pul) and Zlotnicka Spotted (ZS). The count of lactic acid bacteria (4.4 log cfu/g) and the release of palmitic (23.1% and 25.9%), oleic (44.1% and 42.2%), and linoleic acids (8.3% and 7.8%), as well as arginine (30.0 and 44.3 mg/kg), histidine (25.8 and 20.6 mg/kg), and lysine (26.8–22.9 mg/kg), shaped the final pH (5.3 and 5.4) in Pul and ZS products during the 4 week maturing, respectively. Lastly, Pul and ZS meat differed in the proportion of decanoic, lauric, stearic, arachidic, and conjugated linoleic acids. The high content of putrescine (23.7 mg/kg), cadaverine (54.3 mg/kg), and tyramine (57.2 mg/kg), as well as a twofold greater share of histamine (163.2 mg/kg) and tryptamine (9.1 mg/kg), indicated a more advanced decarboxylation of ZS meat. Volatile compounds differentiating Pul and ZS meat were primarily hexanal, 3-hydroxybutan-2-one, phenylacetalaldehyde, 2,3-dimethyl-2-cyclopenten-1-one, 2-cyclopenten-1-one, and 3-methyl- and 2-cyclopenten-1-one. Most marked volatile compounds were obtained as a result of microbial activity (acetic acid, 3-methylbutan-1-ol, ethanol, acetone, and 3-hydroxybutan-2-one), advanced lipid oxidation, and decomposition of secondary oxidation products (hexanal, phenylacetaldehyde, and 2-cyclopenten-1-one).

Effects of different smoking methods on sensory properties, free amino acids and volatile compounds in bacon

BACKGROUND

The aim of this study was to investigate the effects of different smoking methods on sensory properties, free amino acids (FAAs) and volatile compounds (VCs) of bacon. Descriptive analysis was performed using a highly trained panel (n = 9) to evaluate four bacons in sextuplicate. VCs of bacons were analyzed using solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS).

RESULTS

Bacons were significantly different in sensory properties (P < 0.05). Wood smoked bacon (WSB) had a higher smoky and fatty aroma, liquid smoked bacon (LSB) had a higher red color intensity and yellow color intensity, and paper smoked bacon (PSB) had an outstanding texture. Different smoking methods resulted in an increase in total FAAs content, of which paper smoking was significantly higher than the others (P < 0.05). Also, a total of 59 volatile flavor compounds were identified for bacons, aldehydes were the most abundant groups of compounds. Principal component analysis (PCA) can effectively separate the bacons that underwent different smoking methods.

CONCLUSION

The aldehydes and hydrocarbons with high content in PSB improved the overall taste intensity. The color in the sensory attributes was more obvious after LSB processing. The phenols and aromatic hydrocarbons in WSB contributed significantly to the pleasant properties (smoky, fatty). © 2020 Society of Chemical Industry.

Antioxidant activities of peptides derived from mutton ham, Xuanwei ham and Jinhua ham

The aim of the study was to evaluate antioxidant activity of crude peptides with molecular weight less than 3 KDa extracted from Xuanwei ham, Jinhua ham and mutton ham. UPLC-Q-TOF-MS/MS was used for composition analysis of peptides and homologous protein matching. Further, crude peptide (<3 KDa) was purified using G-15 gel filtration chromatography, and the main antioxidant peptide identified. Analysis showed that mutton ham peptide (MHP) has the highest Fe²⁺ chelating ability, whereas Jinhua ham peptide (JHP) had the highest ABTS and DPPH free radical scavenging ability (P < 0.05). A total of 346, 203 and 296 peptides were identified in JHP, Xuanwei ham peptides (XHP) and MHP, respectively. Most of the peptides were derived from myosin, accounting for 21.97% in JHP, 18.72% in XHP, and 21.96% in MHP. Myosin, actin, myoglobin, troponin, tropomyosin and pyruvate kinase proteins were the main source of peptide differences in the three types of dry cured ham.

Fatty Acids and Free Amino Acids Changes during Processing of a Mediterranean Native Pig Breed Dry-Cured Ham

The aim of this work is to analyse the intramuscular fatty acids and the free amino (FAA) acids in Chato murciano dry-cured ham. There are several Mediterranean native pig breeds whose characteristics of derived products have been described, but the impact of lipolysis and proteolysis on Chato murciano dry-cured ham has not yet been studied. Fatty acids and free amino acids were determined in the fresh piece and at 14, 18, 22 and 24 months of manufacturing. Monounsaturated fatty acids are the majority in the neutral lipids and free fatty acid fractions. Lipolysis took place mainly until the 18th month, resulting in a decrease in the levels of fatty acids of neutral lipids (from 95.43% to 83.38%) and polar lipids (from 2.57% to 0.41%), accompanied by a corresponding increase in free fatty acids (from 2% to 16.21%). Neutral lipids hydrolysis provides the main free fatty acids as in other native breeds. Results for FAA showed an increase in concentration during the time preceding the 14th month. From this point onwards, until month 18, total FAA concentration remained stable, and the content decreased at the end of the processing (between months 22 and 24).

Effects of cinnamaldehyde combined with ultrahigh pressure treatment on the flavor of refrigerated Paralichthys olivaceus fillets

The combined effects of cinnamaldehyde (CA) and ultrahigh pressure (UP) treatment on the flavor of olive flounder (Paralichthys olivaceus) fillets during storage at 4 °C for 20 days were investigated. Changes in total viable count, trimethylamine, ATP-related compounds, free amino acids, TCA-soluble peptides, electronic nose (E-nose) analysis and sensory quality were measured. The results indicated that CA and UP treatment, especially CA combined with UP, significantly reduced undesirable flavor compounds including inosine, hypoxanthine, TMA, and bitter amino acids, and accumulated pleasant flavor compounds such as inosine monophosphate and umami-related amino acids. In addition, the combination of CA and UP was shown to be more effective for retarding protein degradation and microbial growth than CA or UP treatment alone. In accordance with the results of E-nose analysis and sensory evaluation, CA combined with UP treatment had great potential for improving the flavor quality of refrigerated flounder fillets and extending their storage life.

The combined effects of cinnamaldehyde (CA) and ultrahigh pressure (UP) treatment on the flavor of olive flounder (Paralichthys olivaceus) fillets during storage at 4 °C for 20 days were investigated.

Hydrolysis and oxidation of protein and lipids in dry-salted grass carp (Ctenopharyngodon idella) as affected by partial substitution of NaCl with KCl and amino acids

To obtain healthier meat products with reduced Na content, the salt substitute containing l-histidine and l-lysine was compared with NaCl in the hydrolysis and oxidation of protein and lipids of dry-salted fish during processing. Compared with NaCl-treated fish (S-F), salt substitute treated fish (SS-F) had a lower Na content, higher moisture content and lower hardness. Sensory analysis showed that salt substitute didn't affect the acceptability of salted fish. The free fatty acids of SS-F treated fish had a slight tendency toward lipolysis at the end of processing. Additionally, the conjugated diene value, lipoxygenase activity and malondialdehyde value were lower in the ventral and dorsal muscles for the SS-F treatment. Meanwhile, the protein carbonyls and thiol groups were significantly decreased as cathepsin B and L activities and FAA content were increased in the ventral and dorsal muscles for the SS-F treatment. l-Histidine and l-lysine accelerated the hydrolysis (inhibit the oxidation) of protein and lipids in dry-salted grass carp, illustrating that l-histidine and l-lysine will be a positive approach to develop healthier meat products.

Quality characteristics of cold-dried beef slices

In this study, salted and pasteurized beef slices were dried to approximately 40% water content at different low temperatures (10, 15 and 20 °C) and air flow rates (1, 2, 3 and 4 m/s) and the quality characteristics of the cold-dried beef slices were investigated. The TBARS values of cold-dried slices increased from 42.01 to 54.54 μmol MDA/kg with the increase in drying temperature and from 27.29 to 67.79 μmol MDA/kg with the increase in air flow rate indicating that low temperature and low air flow rate can help to avoid the lipid oxidation. Low drying temperature was also found to impact on the color of cold-dried slices. Additionally, it was determined that the microbiological quality of cold-dried slices decreased as the temperature increased from 10 to 20 °C and air flow rate increased from 1 to 4 m/s. Finally, the slices dried at 10 °C and 3 m/s had higher sensorial property scores. Consequently, low drying temperature and high air flow rate could enhance the quality of dried beef slices.

Physicochemical and sensory characteristics of dry-cured loin made from pigs fed Allium hookeri added whey powder and sensory trait evaluation using electronic tongue

The aim of this study was to determine the effect of dietary supplementation with Allium hookeri (A. hookeri) added whey powder on the physicochemical characteristics of dry-cured loin (CON, basal diet; AH, addition of 1% A. hookeri; AHW, addition of 0.5% A. hookeri and 4% whey powder) during manufacturing (pre- and post-salting, drying and ripening process) and analyse their sensory characteristics using electronic tongue. Crude fat and weight yield of AH were higher (P &lt; 0.05) than those of CON. The AH inhibited (P &lt; 0.05) lipid oxidation and the reduction of redness during manufacturing. The percentage of some free amino acids (tyrosine, methionine, phenylalanine, isoleucine and leucine) in AHW was higher (P &lt; 0.05) compared with those in CON. Monounsaturated fatty acid composition was the highest (P &lt; 0.05) in AHW. Sensory evaluation by panellists did not show significant differences among the three groups (CON, AH and AHW). However, the richness of AH and AHW was significantly higher compared with that of CON based on electronic tongue analysis. Taken together, these results revealed that AH supplementation with whey powder had higher oxidative stability and enhanced dry-cured loin quality.

The influence of acid whey on the antioxidant peptides generated to reduce oxidation and improve colour stability in uncured roast beef

BACKGROUND

The effect of marinating beef in acid whey on the antioxidant peptides generated, and their influence on lipid oxidation, colour stability, sensory analysis and protein degradation products in uncured roasted beef stored 6 weeks in vacuum conditions (T = 4 °C) were determined. Measurements of pHe, water activity, oxidation-reduction potential, colour, TBARS, the cutting force, texture and amino acid profile, the total content of peptides, and antioxidant activity of isolated peptides were conducted immediately after production and during 42 days of storage.

RESULTS

The non-nitrite control batch (C) was characterized by a lower a* value (6.33-6.70) during the whole storage period compared to the non-nitrite sample with acid whey (W). It also appears that meat with the worst colour stability has the poorest oxidative stability (C = 1.57 mg MDA kg^-1 , W = 0.76 mg MDA kg^-1 ). Activity against reactive forms of oxygen to fraction A and fraction B (P < 0.05) showed an increasing trend with time and it was the largest in sample C and W.

CONCLUSION

The results indicated that bioactive peptides could be generated in uncured roasted beef. The <3.5 kDa peptides have strong antioxidant activity, as a result of which they function as inhibitors of lipid oxidation and colour discoloration during prolonged storage. © 2018 Society of Chemical Industry.

Physicochemical changes of semimembranosus muscle during the processing of dry-cured ham from Celta pig. Effect of crossbreeding with Duroc and Landrace genotypes

Physicochemical characteristics of dry-cured hams from three genetic types, Celta breed (C line), Celta × Duroc (C × D) and Celta × Landrace (C × L) were determined on the semimembranosus muscle during 551 days of aging. Hams were obtained from 60 pigs reared in extensive systems and finished with a commercial feeding. Physicochemical parameters (pH and water activity) and chemical composition, (moisture, intramuscular fat, ash, protein and total chlorides content), colour parameters (L*, a* and b*) and lipid oxidation (thiobarbituric acid reactive substances value) were studied during the whole process after salting, post-salting, drying and bodega stages. Hams from crosses were characterised by higher intramuscular fat (12.78% and 10.48% for C × D and C × L lines, respectively) and moisture (46.86% and 46.63% for C × D and C × L genotypes, respectively), contents respect to Celta pure line that showed values of 5.96% and 35.83% for intramuscular fat and water content, respectively. Concerning colour parameters, hams from Celta line had lower values for all colour traits. The influence of crossbreeding on most physicochemical parameters observed was mainly due to the differences in moisture and intramuscular fat between hams obtained from pure breed and crosses. As a general conclusion, the crossbreeding of Celta pig (especially with the Duroc line) allows to improve the quality of dry-cured hams.

The effects of different processing conditions on biogenic amine formation and some qualitative properties in pastırma

Pastırma, a Turkish dry-cured meat product, was cured at two different temperatures (4 or 10 °C) with two different curing agents (150 mg/kg NaNO₂ or 300 mg/kg KNO₃). The aim of this research was to determine the effects of these factors on biogenic amine content and other qualitative properties (pH, a_w, color, residual nitrite, TBARS, NPN-M, microbiological properties). Residual nitrite was below 10 mg/kg in all samples. Both the curing agent and temperature were found to have a very significant effect on the TBARS value, and the curing agent had a significant effect on the NPN-M content. Curing at 10 °C increased the L* value; the use of nitrate increased the a* value. The use of nitrite had a negative effect on the growth of lactic acid bacteria. Micrococcus/Staphylococcus showed good growth in the presence of nitrate. In all samples, Enterobacteriaceae counts were below detectable levels. Neither temperature nor curing agent had significant effects on the amounts of tryptamine, cadaverine, histamine, tyramine, or spermine. There were very significant effects of temperature on the amount of putrescine and of the curing agent on the amount of spermidine.

Physicochemical and sensory properties of dry-cured ham with dietary processed-sulfur supplementation

The aim of the present study was to explore the changes in physicochemical and sensory properties of dry-cured ham (from pigs that received a dietary supplement of processed sulfur, PS), as a function of the level of dietary PS. The following three groups were tested: (1) commercial basal feed (control, CON); (2) 0.1% of PS in the control diet (T1); and (3) 0.3% of PS in the control diet (T2). Dry-cured ham from T2 pigs had a higher moisture content and lower fat concentration than did that from the control pigs. Dry-cured ham T1 and T2 samples showed excellent lipid oxidation stability during storage and showed positive aroma scores in comparison with CON samples. Nonetheless, the total microbial plate count of dry-cured ham T1 (or T2) samples was significantly lower than that of CON samples, and volatile basic nitrogen of T1 (or T2) samples was higher than that of CON samples (P < 0.05). Concentrations of total free amino acids and sulfur-containing amino acids of ham T1 or T2 samples were significantly (P < 0.05) higher than those of control samples. Concentrations of polyunsaturated fatty acids of ham T1 and T2 samples were significantly higher than that of CON samples, whereas concentration of saturated fatty acids of CON samples was significantly higher. Thus, dry-cured ham from pigs receiving 0.3% PS in the diet showed the lowest fat concentration, increased nutrient quality and extended shelf life.

Effects of Processing Temperature on Color Properties of Dry-Cured Hams Made without Nitrite

Dry cured hams were investigated for their ability to develop red color even at low temperature (3–4 °C) and in the absence of added nitrites; results were compared with those obtained from nitrite-free hams made at conventional warm maturing temperatures. Colorimetric parameters (L*, a*, b*, and hue) and concentration of the main pigments Zn protoporphyrin IX (ZnPP) and heme were measured at three stages of preparation (six, nine, and 12 months), showing that red color was successfully formed at low temperatures, though at a slower rate and less intensively than under warm conditions. Major differences in the pattern of color development were found with the two processing temperatures. While the typical features of an enzyme-dependent mechanism, with a progressive drop in enzyme activity paralleling the synthesis of Zn protoporphyrin IX, were observed at warm temperatures, the same did not occur in cold-made hams, where the enzyme activity was almost unchanged throughout the process. These results, along with data from a descriptive sensory analysis, are supportive of a non-enzymatic mechanism leading to ZnPP (hence the red color) under cold conditions, with an estimated three-month delay compared with nitrite-free hams manufactured in a warm maturing regimen.

Effect of Dietary Processed Sulfur Supplementation on Texture Quality, Color and Mineral Status of Dry-cured Ham

This study was performed to investigate the chemical composition, mineral status, oxidative stability, and texture attributes of dry-cured ham from pigs fed processed sulfur (S, 1 g/kg feed), and from those fed a basal diet (CON), during the period from weaning to slaughter (174 d). Total collagen content and soluble collagen of the S group was significantly higher than that of the control group (p<0.05). The pH of the S group was significantly higher than that of the control group, whereas the S group had a lower expressible drip compared to the control group. The S group also showed the lower lightness compared to the control group (p<0.05). In regard to the mineral status, the S group had significantly lower Fe(2+) and Ca(2+) content than the control group (p<0.05), whereas the proteolysis index of the S group was significantly increased compared to the control group (p<0.05). The feeding of processed sulfur to pigs led to increased oxidative stability, related to lipids and pigments, in the dry-cured ham (p<0.05). Compared to the dry-cured ham from the control group, that from the S group exhibited lower springiness and gumminess; these results suggest that feeding processed sulfur to pigs can improve the quality of the texture and enhance the oxidative stability of dry-cured ham.