Evolution of volatile hydrocarbons from subcutaneous fat during ripening of Iberian dry-cured ham. A tool to differentiate between ripening periods of the process

UPLC-MS-MS-based lipidomics for the evaluation of changes in lipids during dry-cured mutton ham processing

Six key stages in the processing of dry-cured muton ham were selected, and changes in the main lipid metabolites as well as the major pathways involved were identified using a lipidic metabolomics approach based on UPLC-MS-MS. In total, 581 lipid metabolites from 22 subclasses were identified, including 521 significantly differential lipids (p < 0.05, VIP > 1). Glycerolipids (GL) were the most abundant lipids, followed by glycerophospholipids (GP), fatty acyls (FA), and sphingolipids (SL). PCA and OPLS-DA of metabolites showed that the quality of mutton ham changed the most during the P3 fermenting stage, including TG(18:1/18:2/18:3), PE(20:5/18:1), and TG(16:1/18:1/18:4) that were significantly downregulated, and CE(20:3), FFA(24:6), LPC(20:3/0:0), and FFA(18:4) that were significantly upregulated. Moreover, glycerophospholipid metabolism and sphingolipid metabolism were the key metabolic pathways involved in the processing of dry-cured mutton ham. Our results provide a basis for quality control and product improvement of dry-cured mutton ham.

Characterization of Subcutaneous Fat of Toscano Dry-Cured Ham and Identification of Processing Stage By Multivariate Analysis Approach Based on Volatile Profile

During ham processing the action of endogenous proteolytic and lipolytic enzymes leads to the development of volatile compounds (VOCs) responsible of typical aromas. Protected Designation of Origin (PDO) of Toscano ham requires at least 12 months of ripening but extended seasoning might improve flavor and economic value. This study aimed at assessing the evolution of color, fatty acids, and VOCs profile in subcutaneous fat, and, among VOCs, at identifying possible markers characterizing different seasoning length. For this purpose, a reduced pool of VOCs was selected by 3 multivariate statistical techniques (stepwise discriminant analysis, canonical discriminant analysis and discriminant analysis) to classify hams according to ripening (<12 months) or seasoning (≥12 months) periods and also to seasoning length (S12, S14, S16, or S18 months). The main VOCs chemical families steadily increased along ripening. Aldehydes and hydrocarbons reached their peaks at S16, acids and ketones remained constant from R6 to S16, whereas esters started decreasing after 12 months of seasoning. Stepwise analysis selected 5 compounds able to discriminate between ripening and seasoning periods, with 1,1-diethoxyhexane and dodecanoic acid being the most powerful descriptors for ripening and seasoning period, respectively. Instead, 12 compounds were needed to correctly classify hams within seasoning. Among them, undecanoic acid methyl ester, formic acid ethyl ester, 2,4,4-trimethylhexane, and 6-methoxy-2-hexanone had a central role in differentiating the seasoning length.

Influence of dietary inclusion of tannin extracts from mimosa, chestnut and tara on volatile compounds and flavour in lamb meat

Tannins are compounds able to form complexes with proteins limiting their ruminal degradation and thus the synthesis of some odour-active compounds may be inhibited. Tannins are broadly divided in condensed tannins (CT) and hydrolysable tannins (HT). The study aimed to assess the influence of dietary inclusion of three commercial tannin extracts, namely mimosa (Acacia mearnsii; CT), chestnut (Castanea sativa; HT) or tara (Caesalpinia spinosa; HT) on volatile profile and flavour of meat and kidney fat from lambs. Comisana male lambs were divided into four groups (n = 9 each) and fed for 75 days with a concentrate-based diet (CON) or CON supplemented with 4% of one of the tannin extracts. Tannins reduced "pastoral" odour in perirenal fat of lambs the meat of which was characterized by a very low perception of this attribute. It may be assumed that p-cresol and 8-methylnonanoic acid mostly contributed to "pastoral" odour expression in the diet without condensed or hydrolysable tannins.

Differentiation between Ripening Stages of Iberian Dry-Cured Ham According to the Free Amino Acids Content

In this paper, the differentiation of three ripening stages, postsalting, drying, and cellar, of Iberian dry-cured ham has been carried out according to their free amino acids contents. Eighteen L-amino acids, alanine, 2-aminobutanoic acid, aspartic acid, cysteine, glutamine, glycine, histidine, hydroxyproline, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tyrosine, and valine have been determined by gas chromatography with derivatization with N,O-bis(trimethylsilyl)-trifluoroacetamide. Gas chromatography-mass spectrometry was used to confirm the presence of the eighteen amino acids in the ham samples, and gas chromatography using a DB-17HT column and flame ionization detector was used for quantitative determination. Extraction with a mixture methanol-acetonitrile has been carried out, achieving recoveries in the range 52-164%. Methimazole was used as internal standard. Limits of detection ranged between 7.0 and 611.7 mg·kg-1. Free amino acids have been used as chemical descriptors to differentiate between the ripening stages. Principal component analysis and linear discriminant analysis have been used as chemometric techniques, achieving complete differentiation between the ripening stages. Alanine, tyrosine, glutamine, proline, 2-aminobutanoic acid, cysteine, and valine were the most differentiating amino acids.

Sensory properties and metabolomic profiles of dry-cured ham during the ripening process

Dry-cured ham with a long ripening period is a valuable product worldwide. Ripening time is a key determinant of the endogenous metabolites that characterize the flavor and taste of ham products. While various studies have analyzed the relationship between ripening duration and sensory characteristics, no studies have evaluated ham products produced in Japan. Here, we conducted time-course metabolomic profiling, taste sensor-based analyses, and sensory evaluations by non-trained consumers during ripening. Capillary electrophoresis-mass spectrometry was used to quantify non-volatile metabolites, such as amino acids, organic acids, and nucleotides. In an analysis of eight time-points during 680 days of ripening, the highest score for the after-taste of umami was observed on day 540, despite subtle changes in the scores for other properties. The concentrations of aspartic acid and glutamic acid relative to those of total amino acids were the highest at this point. This approach can contribute to the understanding of the relationship between the metabolite profile and ripening duration.

Investigation of low molecular weight peptides (<1 kDa) in chicken meat and their contribution to meat flavor formation

BACKGROUND

Low molecular weight peptides (LMWPs) (<1 kDa) generated in meat during chilled conditioning can act as flavor precursors in the Maillard reaction with a potential contribution to key volatile organic compound (VOC) formation upon heating. Liquid chromatography/quadrupole time-of-flight mass spectrometry (LC/QTOF-MS) successfully detected 44 LMWPs in chicken breast and thigh muscles stored at 4 °C for up to 6 days. Carnosine (350 mg per 100 g), glutathione (GSH, 20 mg per 100 g) (concentrations based on reported values in the literature) and cysteine glycine (Cys Gly, 5 mg per 100 g) (concentration based on results from LC/QTOF-MS) were used in model systems containing ribose (25 mg per 100 g). The three model systems were heated at 180 °C for 2 h at pH 6.3. VOCs were measured by simultaneous distillation solvent extraction/gas chromatography/mass spectrometry.

RESULTS

Of 33 VOCs detected, 26 were significantly different (P ≤ 0.05) between the three peptides. The majority of nitrogen-containing volatiles, pyrazines and pyridines, dominated the carnosine mixture, while sulfur-containing VOCs dominated the GSH and Cys Gly peptide mixtures.

CONCLUSION

Known key aroma compounds such as thiazole (meaty), 2-methyl-3-furanthiol (beef and meat), 2-furfurylthiol (roasted), dihydro-2-methyl-3(2H)-thiophenone (meaty), 2-acetylthiazole (meaty and roasted) and pyrazine (meaty) were detected under conditions specific to aged and thermally treated chicken, suggesting a potential contribution to the overall sensory quality of cooked meat. © 2018 Society of Chemical Industry.

Study of volatile alcohols and esters from the subcutaneous fat during ripening of Iberian dry-cured ham. A tool for predicting the dry-curing time

Variations in the amounts of volatile alcohols and esters from subcutaneous fat have been assessed during the dry-curing process (1022 days) of Iberian ham according to a purge and trap-gas chromatography-mass spectroscopy method, using the same hams throughout the process. During processing time, the subcutaneous adipose tissues of ten hams obtained from five Iberian pigs fed on acorns and pasture were sampled and analyzed once per month. Fifteen alcohols and five esters have been identified. All volatile alcohols detected in this work have been previously identified by other authors on Iberian ham, except 3-buten-2-ol, 5-methyl-3-hexanol and 2-isononanol. A linear discriminant analysis (LDA) was applied and the two discriminant functions were obtained using backward stepwise analysis retaining the following variables: butyl ester formic acid, 1-penten-3-ol, methyl ester 2-propenoic acid, 5-methyl-3-hexanol, 1-nonanol, ethyl ester pentanoic acid, ethyl ester hexanoic acid, 2-isononanol, ethanol and 3-buten-2-ol. A complete separation among the three periods was obtained, suggesting that the retained variables are powerful descriptors to distinguish samples from these three dry-curing stages.