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

Abstract

SUMMARY: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. KEYWORDS: Iberian ham; Patter recognitions; Purge and Trap; Ripening; Volatile alcohols; Volatile estersRESUMEN: Estudio de los alcoholes y ésteres volátiles de la grasa subcutánea durante la maduración del jamón ibérico. Una herramienta para predecir el tiempo de curación. Se han evaluado durante el proceso de curación (1022 días), las variaciones en los contenidos de alcoholes y ésteres volátiles de la grasa subcutánea del jamón ibérico mediante la técnica de acoplamiento purga y trampa-cromatografía de gases-espectrometría de masas, utilizando los mismos jamones a lo largo de todo el proceso. Durante el tiempo de curación se muestreó y analizó una vez al mes el tejido adiposo subcutáneo de diez jamones procedente de cinco cerdos ibéricos alimentados con bellotas y pastos. Se han identificado quince alcoholes y cinco ésteres volátiles. Todos los alcoholes descritos en este trabajo han sido identificados previamente por otros autores en el jamón ibérico, excepto el 3-buten-2-ol, el 5-metil-3-hexanol y el 2-isononanol. Un análisis lineal discriminante por pasos (LDA) fue aplicado y se obtuvieron dos funciones discriminantes las variables incluidas en el modelo fueron: formiato de butilo, 1-penten-3-ol, 2-propenoato de metilo, 5-metil-3-hexanol, 1-nonanol, pentanoato de etilo, hexanoato de etilo, 2-isononanol, etanol y 3-buten-2-ol. Obteniéndose una completa separación entre los tres períodos, lo que sugiere que las variables indicadas son poderosos descriptores para distinguir entre las tres etapas de curación.

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

“…Alcohols showed a very regular trend constantly increasing from R0 to S16 when the greatest amount for almost every compound was observed. The great increase of this family from green to seasoned fat of dry-cured ham is in accordance with results reported by Narváez-Rivas et al [ 47 ]. After the 16th month of seasoning, they dropped at lower values.…”

“…Flores et al [ 46 ] proposed that esters could also be formed from the interaction of free fatty acids and alcohols generated by lipid oxidation in intramuscular tissues. In our study twenty esters were observed, which is a quite high number if compared with results reported by several authors [ 38 , 47 ]. It is worth noting that most of the studies on ham employed samples of Biceps femoris or Semimembranosus muscles, in which the fat content was very low compared to our samples.…”

“…These microorganisms were previously found in ham and associated with a significant lipolytic activity [ 35 ]. Esters developed during the ripening process, resulting thus significantly higher in finished products respect to green hams [ 47 ]. Accordingly, in the present study, the highest concentration of these compounds was observed at the end of ripening, in S12 samples ( Figure 1 ).…”

“…Alcohols detected in subcutaneous fat consisted of 12 compounds. Most of them were also observed in fat [ 47 ], whole slice [ 30 ], and lean tissue [ 58 ] of Iberian ham [ 45 ] and Toscano ham [ 11 , 59 ]. Alcohols showed a very regular trend constantly increasing from R0 to S16 when the greatest amount for almost every compound was observed.…”

The extent to which genetics and lean grade affect fatty acid profiles and volatile compounds in organic pork

“…The VC were classified based on their origin (lipolysis, proteolysis and microbial), according to Dainty, Edwards & Hibbard (1985), Roger, Degas & Gripon (1988), Ruiz et al (1999), Meynier et al (1999), Carrapiso et al (2002), Arnoldi (2003), Liu (2003), Machiels et al (2003), Raes et al (2003), Martín et al (2006), Ramírez & Cava (2007), Calkins & Hodgen (2007), Narváez-Rivas, Gallardo & León-Camacho (2012), Fonseca et al (2015), Rivas, Gallardo & Camacho (2016) and Pérez-Santaescolástica et al (2019).…”