Changes in proteins during the ripening of Spanish dried beef ‘Cecina’

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.

Purification and Chemical Characterization of a Potent Acaricide and a Closely Related Inactive Metabolite Produced by Eurotium rubrum C47

Mites are arthropods and some of them infest dry meat cured products and produce allergic reactions. Some mites, such as Tyrolichus casei, Tyrophagus putrescentiae, or Tyrophagus longior feed on filamentous fungi that grow during the meat curing process. Removal of mite infestation of meat products is extremely difficult and there are no adequate miticidal compounds. The filamentous fungus Eurotium rubrum growing on the surface of ham is able to exert a biocontrol of the population of mites due to the production of miticidal compound(s). We have purified two compounds by silica gel chromatography, gel filtration, semipreparative and analytical HPLC and determined their miticidal activity against T. casei using a mite feeding assay. Mass spectrometry and NMR analysis showed that these two compounds are prenylated salicilyl aldehydes with a C-7 alkyl chain differing in a double bond in the C-7 alkyl chain. Structures correspond to those of flavoglaucin and aspergin. Pure flavoglaucin has a miticidal activity resulting in more than 90% mite mortality whereas aspergin does not affect the mites. Both compounds were formed simultaneously by E. rubrum C47 cultures in different media suggesting that they are synthesized by the same pathway. Production of both compounds was higher in solid culture media and the products were associated with abundant formation of cleistothecia. In liquid cultures both compounds remained mainly cell-associated and only about 10% of the total compounds was released to the culture broth. This miticidal compound may be used to combat efficiently mite infestation in different habitats. These results, will promote further advances on the utilization of flavoglaucin in food preservation and in human health since this compound has antitumor activity.

Biological control of mites by xerophile Eurotium species isolated from the surface of dry cured ham and dry beef cecina

Some meat dry products, including dry cured ham and dry beef cecina, are cured in cellars at moderately cold temperature allowing the growth of a lawn of fungi on their surface. During the curing process, frequently these products became contaminated with fungivore mites of the Acaridae family that feed on fungal mycelium and spores.

AIMS

The aim of this article is to study the possible biological control of mites by fungi that form part of the normal microbiota of these meat products.

METHODS AND RESULTS

Some yellow/orange pigmented fungi growing on the ham surface decreased the proliferation of mites; therefore, we isolated from ham and cecina xerophilic yellow/orange coloured fungal strains that were identified as members of the genus Eurotium (recently reclassified as Aspergillus section Aspergillus). Using molecular genetic tools, we have identified 158 strains as Eurotium rubrum (Aspergillus ruber), Eurotium repens (Aspergillus pseudoglaucus) and Eurotium chevalieri (Aspergillus chevalieri). Two strains, E. rubrum C47 and E. rubrum C49, showed strong miticidal activity. The toxic compound(s) are associated with the formation of cleistothecia. In synchronized mite development experiments, we observed that all stages of the mite lifecycle were inhibited by the E. rubrum C47 strain. In addition, we searched for miticidal activity in 13 culture collection Eurotium strains isolated from different habitats, and found that only one, Eurotium cristatum NRRL 4222 (Aspergillus cristatus) has a strong miticidal activity.

CONCLUSIONS

These fungal strains have proliferated on the surface of ham and cecina for decades, and possibly have acquired miticidal activity as a resistance mechanism against fungivores.

SIGNIFICANCE AND IMPACT OF THE STUDY

Biological control of infecting mites by favouring growth of E. rubrun C47, in place of the normal mixed population of Aspergillus and Penicillium, is an attractive approach to control mite infestations.

Identification of small peptides arising from hydrolysis of meat proteins in dry fermented sausages

In this study, proteolysis and low molecular weight (LMW) peptides (<3kDa) from commercial Argentinean fermented sausages were characterized by applying a peptidomic approach. Protein profiles and peptides obtained by Tricine-SDS-PAGE and RP-HPLC-MS, respectively, allowed distinguishing two different types of fermented sausages, although no specific biomarkers relating to commercial brands or quality were recognized. From electrophoresis, α-actin, myoglobin, creatine kinase M-type and L-lactate dehydrogenase were degraded at different intensities. In addition, a partial characterization of fermented sausage peptidome through the identification of 36 peptides, in the range of 1000-2100 Da, arising from sarcoplasmic (28) and myofibrillar (8) proteins was achieved. These peptides had been originated from α-actin, myoglobin, and creatine kinase M-type, but also from the hydrolysis of other proteins not previously reported. Although muscle enzymes exerted a major role on peptidogenesis, microbial contribution cannot be excluded as it was postulated herein. This work represents a first peptidomic approach for fermented sausages, thereby providing a baseline to define key peptides acting as potential biomarkers.

Shelf life study of hurdle treated ready-to-eat spiced buffalo meat product stored at 30 ± 3 °C for 7 weeks under vacuum and aerobic packaging

Shelf stable ready to eat spiced pickle type buffalo meat product was prepared after desorbing in infusion solution (glycerol 3.5%, sodium chloride 5.0%, honey2.0%, mango powder 2.2%, spices 1.0%, sodium nitrite 0.015%, phosphate 0.2%, Sorbic acid 0.2%.and acetic acid 1%), pressure cooking of meat in infusion solution for 20 min followed by frying for 2 min in mustard oil and mixing with prefried condiments and spices. The physico-chemical properties i.e. pH, water activity, proximate composition, FFA, Soluble hydroxyproline, TBA values, nitrite content, protein solubility, shear force value, haempigments, microbiological and sensory quality of the product remained good and hygienically safe and almost comparable in aerobic PET jars and multilayered nylon barrier pouches stored at 30 ± 3 °C for 7 weeks .It can be suggested that storage of such product may be conveniently done even in food grade PET jars without going for vacuum packaging which is a bit costly.

Changes on physico-chemical, textural, lipolysis and volatile compounds during the manufacture of dry-cured foal "cecina"

The changes in the physico-chemical and textural properties, lipolysis and volatile compounds during the manufacture of dry-cured foal "cecina" were studied. The pH increased during the last stages of processing but gradually declined over the curing period. TBARS values, hardness and chewiness increased with processing time from 0.14, 2.74 and 0.83 to 3.49 mg malonaldehyde/kg, 20.33 kg and 5.05 kg∗mm, respectively. Ripening time also affected the colour parameters: lightness (L*), redness (a*) and yellowness (b*) (P<0.001). The total average content of free fatty acid (FFA) increased significantly from 433.7 mg/100 g of fat in the raw pieces to 2655.5 mg/100 g of fat at the end of the drying-ripening stage. The main FFA at the end of the manufacturing process was palmitic acid (C16:0), followed by oleic (C18:1cis9), stearic (C18:0) and linoleic (C18:2n-6). A total of fifty five volatile compounds were identified during the manufacture of dry-cured foal "cecina", including esters, aldehydes, aliphatic hydrocarbons, branched hydrocarbons, alcohols, aromatic hydrocarbons, furans, ketones. Aldehydes reached their maximum level at the end of the post-salting stage. In the final product, esters became the dominant chemical compounds.

Proteolytic activity of beef luncheon fungi as affected by incorporation of some food preservatives

Screening of thirty-one fungal isolates (representing 16 genera, 28 species and 3 varieties) collected from beef luncheon meat for their abilities to produce protease enzyme revealed that eleven isolates (35.48%) exhibited high protease production. However, fifteen isolates (48.39%) had moderate ability and 5 isolates (16.13%) were low producers. Aspergillus flavus, Gibberella fujikuroi and Penicillium chrysogenum were the most active producers of protease. The incorporation of five chemical substances used as food preservatives (disodium phosphate, sodium benzoate, citric acid, potassium sorbate and sodium citrate) individually in the culture medium for protease production exhibited depressive effect on protease production as well as on mycelial growth of Aspergillus flavus, Gibberella fujikuroi and Penicillium chrysogenum , except in few cases the mycelial growth of A. flavus and G. fujikuroi was increased by the lowest concentration (100 ppm) of sodium benzoate, citric acid and disodium phosphate.

The Anatomical Origin of Raw Meat Affects the Sensory and Chemical Characteristics of a Dry-Cured Beef Product: Cecina de León

This study presents the chemical composition and physicochemical and sensory properties of Spanish Cecina de León manufactured from three anatomical retail cuts (knuckle or babilla, topside or tapa, and silverside or contra). The silverside samples presented significantly ( p<0.05) more fat, and in consequence, less protein, carbohydrate, and ash content than the knuckle and the topside. The fatty acid profiles showed the knuckle samples as having less oleic acid and less monounsaturated fatty acids ( p<0.05) and showed its ratio of polyunsaturated and saturated fatty acids as falling below dietary recommendations (>0.4). On the other hand, the knuckle and the silverside showed more balanced ω6/ω3ratio (3.5). No differences ( p>0.05) were found between any of the sensorial parameters, except the textural ones: hardness, pastiness, and chewiness being higher in the silverside. Intermuscular fat was also higher ( p<0.05) in this cecina.

Proteolytic and lipolytic modifications during the manufacture of dry-cured lacón, a Spanish traditional meat product: Effect of some additives

The extractability of sarcoplasmic and myofibrillar proteins, the myofibrillar proteins and their degradation products, classical nitrogen fractions, free amino acids, acidity of the fat, and free fatty acids were determined throughout the manufacturing process of dry-cured lacón, a traditional dry-salted and ripened meat product made in the northwest of Spain from the foreleg of the pig, following a similar technological process to that of dry-cured ham. The effect of the use of additives (glucose, sodium nitrite, sodium nitrate, sodium ascorbate and sodium citrate) on the proteolytic and lipolytic changes was also studied. Throughout the manufacture, approximately 87% of the sarcoplasmic proteins and 91% of the myofibrillar proteins became insoluble. There was a significant (p<0.05) decrease of the myosin heavy chain, actin, and myosin light chains 1, 2 and 3, and also a significant (p<0.05) increase in the components generated as a result of the degradation of these myofibrillar proteins. The content of the different nitrogen fractions and of the free amino acids indicated that protein degradation during the manufacture of dry-cured lacón is only moderate. Data on the acidity of fat and of free fatty acids also indicated that lipolysis in dry-cured lacón is lower than in hams. The use of additives did not significantly influence the protein and lipid degradation, which occur throughout the manufacturing process.

Effect of protease EPg222 obtained from Penicillium chrysogenum isolated from dry-cured ham in pieces of pork loins

The fungal protease EPg222 obtained from Penicillium chrysogenum Pg222 isolated from dry-cured ham, was assayed for proteolytic activity in a meat model system based on sterile pieces of pork loins for 32 days. Treated samples showed a significative reduction of total high ionic strength-soluble proteins during the incubation period, as compared with a control incubated without enzyme, both on the surface and in the depth. SDS-PAGE analysis of this protein fraction showed higher hydrolysis of the main myofibrillar proteins H-meromyosin, actin, and tropomyosin in treated samples. Non-protein and amino acidic nitrogen were detected in higher amounts in enzyme-added than in control pieces of loins, both on the surface and in the depth. Thus, addition of enzyme EPg222 to whole pieces of meat results in an increase of protein hydrolysis. The effect of this enzyme could be of great interest for stimulating proteolysis in whole dry-cured meat pieces.

Evaluation of proteolytic activity of micro-organisms isolated from dry cured ham

In order to determine the possible contribution of micro-organisms to the ripening of meat products, 48 cocci, 18 moulds and 20 yeasts isolated from dry-cured Iberian ham were evaluated for proteolytic activity. Two specific methods were used: the ability to hydrolyse myosin in broth and, for those strains showing high activities, hydrolysis on both myofibrillar and sarcoplasmic proteins on pork slices. Moulds and cocci showed the highest proteolytic activity for myosin in broth. Both myofibrillar and sarcoplasmic proteins were recovered at lower rates from inoculated than from sterile incubated pork. The deepest changes in myofibrillar and sarcoplasmic proteins were originated by one strain each of Penicillium chrysogenum and Staphylococcus xylosus, respectively. Only small changes were observed in the concentrations of free amino acids from inoculated pork slices, except for the samples with P. chrysogenum, where there were increases in all free amino acids. Thus, P. chrysogenum makes a significant contribution to proteolysis during the ripening of dry-cured meat products.