Evolution of volatile aldehydes in Iberian ham matured under different processing conditions

To evaluate the influence of the Iberian ham processing conditions in the evolution of volatile aldehydes, 35 hams were processed in two plants following different conditions of relative humidity and temperature. For this, free fatty acids, peroxide values and volatile aldehydes were quantified in the hams. The highest increases in free fatty acids were noted during the drying stage in both processing plants. The drying period also revealed the greatest increase in peroxide values, where the highest values were in those hams processed at higher temperatures. The temperature during post-salting and drying had a marked influence on the formation of volatile aldehydes, being responsible for the differences in volatile compounds of matured hams.     

Impact of pre-selected autochthonous starter cultures on the flavor quality of Iberian dry-fermented "salchichón" sausage with different ripening processes

The purpose of this study was to investigate the impact on flavor quality of 2 autochthonous starter cultures in the manufacture of Iberian dry-fermented "sálchichón." A total of 2 strains of Pediococcus acidilactici (MS200 and MS198) were combined individually with a strain of Staphylococcus vitulus (RS34) to obtain 2 starter cultures: P200S34 and P198S34. The ability of both starter cultures to implant during 2 different manufacturing procedures of "salchichón" was evaluated by 16S rRNA gene sequence analysis. Changes due to starter culture inoculations on volatile compounds were determined by gas chromatography/mass spectrometry, and the impact on flavor quality evaluated by sensorial analysis. The implantation of starter cultures was adequate and did not significantly modify the flavor of the traditional Iberian dry-fermented "salchichón," while modulating the volatile compound profile with respect to that found in sausages with wild microbial populations. The influence of the starter cultures studied was more evident in the shorter sausage processing time. P198S34 was related with the increase in some volatile compounds deriving from lipid degradation. P200S34 contributed to the formation of several volatile compounds arising from lipid degradation, amino acid catabolism, and microbial esterase activity. PRACTICAL APPLICATION: P200S34 and P198S34 are autochthonous starter cultures for specific use in the processing of Iberian dry-fermented sausages. The application of these starters allows obtaining Iberian dry-fermented sausages with sensorial characteristics standardized. It is greatly interesting for processing and marketing industry of these high-quality meat products.     

Influence of pre-cure freezing of Iberian ham on proteolytic changes throughout the ripening process

This work aimed to investigate the effect of pre-cure freezing Iberian hams on proteolysis phenomena throughout the ripening process. Non-protein nitrogen (NPN), peptide nitrogen (PN) and amino acid nitrogen (AN) as well as amino acid and dipeptide evolution followed the same trend in both refrigerated (R) and pre-cure frozen (F) Iberian hams during processing. At the different stages of ripening, there were no differences in the content of NPN and AN while F dry-cured hams had higher levels of PN than R hams at the final step. This seemed to be more related to the salt content (lower in F than in R hams) than to the pre-cure freezing treatment. Most amino acids and dipeptides detected showed higher concentrations in F than in R Iberian hams at the green stage, being rather similar at the intermediate phases. At the final stage, the effects of pre-cure freezing of Iberian hams were not well defined, higher levels of some amino acids and dipeptides were found in R than in F Iberian hams whereas other amino acids were lower in R than in F hams.     

Influence of pre‐cure freezing on the profile of volatile compounds during the processing of Iberian hams

BACKGROUND: This work was designed to study the effect of pre‐cure freezing of raw thighs from Iberian pigs on the profile of volatile compounds during the processing of hams. RESULTS: Generation of volatile compounds during Iberian ham processing was similar in both pre‐cure frozen and refrigerated hams, the main differences being at the final stage. The levels of 2‐methylbutanal, 2‐methyl‐1‐butanol, 2,3‐butanediol and 2‐heptanol were significantly higher in dry‐cured hams that were pre‐cure frozen than in refrigerated ones, whereas the content of most detected esters was statistically lower in pre‐cure frozen than in refrigerated hams. CONCLUSION: The effect of pre‐cure freezing of Iberian ham on the profile of volatile compounds during ripening was not remarkable. Few differences were found in the final product, which would not greatly modify the aroma and flavour features of the dry‐cured hams. Copyright © 2010 Society of Chemical Industry     

Interactions between non-volatile water-soluble molecules and aroma compounds in Camembert cheese

Interactions between selected aroma compounds and non-volatile water-soluble molecules were studied using dynamic headspace-gas chromatography. A model water-soluble extract (MWSE), previously constructed in gustatory and physico-chemical accordance with the crude Camembert cheese WSE, allowed the contribution of non-volatiles to the headspace composition of volatile compounds to be assessed. The presence of the MWSE increased the headspace concentration of 2-heptanone, 1-octen-3-ol and 3-methylbutanol, showing that these three volatile compounds were released by MWSE. Omission tests performed on MWSE allowed for the impact of each MWSE component on aroma compounds release to be determined. The releasing influence of minerals appeared as the main effect observed for the three volatiles, despite some retention phenomena due to other MWSE components also occurring. In the case of 2-undecanone, 2-nonanol, 2,4-dithiapentane and ethylhexanoate, which were not affected by the presence of MWSE, some significant compensatory effects were observed. Whereas amino acids had no significant effect, minerals might cause their release and the presence of peptides can either decrease or increase headspace concentration of aroma compounds. Possible antagonistic effects between MWSE components are discussed.     

Formation and characterisation of melanoidin-like polycondensation products from amino acids and lipid oxidation products

Various coloured water-soluble high molecular weight and water-nonsoluble reaction products were isolated from model reactions of an amino acid (glycine or lysine) and a lipid oxidation product (hexanal, (2E)-hexenal, (2E, 4E)-decadienal) with or without glucose. They were characterised by UV–visible absorbance measurements, elementary analysis, and thermal degradation followed by SPME–GC–MS analysis. The UV–visible absorbance spectra before and after dialysis indicated that the most important contributors to the formation of water-soluble coloured material were constituents of the low molecular fraction. Elementary analysis data indicated that a higher amount of nitrogen was incorporated in the high molecular weight fractions as compared to the water-nonsoluble fractions, except for the water-nonsoluble reaction products from amino acid/(2E, 4E)-decadienal interactions, which showed the lowest C/N ratio found. Volatile carbonyl compounds, furans, aliphatic compounds, pyridines, pyrroles and benzene derivatives were the main groups identified in the thermal degradation profile of each fraction tested. Especially pyridines seem typical indicators of amino acid–lipid oxidation product interactions.     

金针菇和茶树菇中非挥发性成分分析

对金针菇和茶树菇中非挥发性成分进行研究,对2种食用菌非挥发性成分甘露醇、核苷酸、游离氨基酸进行对比分析。结果表明:金针菇中甘露醇含量明显高于茶树菇;茶树菇中呈鲜味的核苷酸及氨基酸含量明显高于金针菇。金针菇和茶树菇在非挥发性成分上存在较大差别,茶树菇中非挥发性成分较金针菇丰富;非挥发性成分的差异是引起金针菇和茶树菇感官差别的主要原因。     

肉的风味物质及其检测技术研究进展

肉品的风味特佂是决定其品质的重要指标之一,肉的风味物质主要是由肉中水溶性小分子化合物和脂肪酸经热诱导后形成非挥发性的滋味物质和挥发性的气味物质构成,具有微量性、多样性和复杂性的特点。风味好坏直接影响肉品质及消费选择。本文主要介绍肉品风味物质的形成途径、影响因素及其检测分析技术,展望肉品风味研究趋势,为肉品风味物质研究提供理论指导依据。     

香菇热风干燥过程中香气形成机理初探

通过感官分析香菇香味形成的非挥发性成分的变化,对香菇热风干燥过程中的香气形成机理进行了研究。香菇热风干燥过程的香气形成可分为2个阶段:即干燥初期和中期的酶的作用产生香味物质以及前驱体,和干燥后期的美拉德反应产生香味物质。     

酱油特征性风味物质研究进展

酱油的风味是决定其品质的关键性因素之一,但风味的形成途径复杂且难以控制。本文通过蛋白质降解、淀粉的糖化、脂肪的水解、菌种微生物的代谢作用角度分析了酱油风味形成途径及其机理,并总结了酱油挥发性和非挥发性风味物质的分离及鉴别技术,如溶剂直接萃取、吹扫捕集、固相微萃、电子鼻和电子舌等,以期为酱油加工技术及挥发性和非挥发性风味物质的检测提供理论依据和指导作用。     

Influence of pre-cure freezing of Iberian hams on lipolytic changes and lipid oxidation

The purpose of this work was to study the influence of pre-cure freezing of Iberian hams on lipolysis and lipid oxidation during the ripening of the product. At the green stage, the levels of fatty acids (FA) in the free fatty acids fraction were higher in pre-cure frozen (F) than in refrigerated (R) hams, whereas in the polar lipid fraction, FA and dimethyl acetals (DMA) values were higher in R than in F Iberian hams. These results point out the existence of lipolysis phenomena during the freezing storage. At the end of post-salting and at the final stage, both R and F hams showed similar FA and DMA profiles. The effect of pre-cure freezing of hams influenced lipolysis evolution throughout the processing. The development of lipid oxidation was similar in R and F hams, but Thiobarbituric acid-reactive substances (TBAR) values were significantly higher in F hams at the initial stage and at the end of post-salting and drying steps. Despite all these differences, at final stage the FA and DMA composition as well as TBAR levels were quite similar in R and F hams.     

Effect of salt content and processing conditions on volatile compounds formation throughout the ripening of Iberian ham

Volatile compounds evolution throughout the ripening of dry-cured Iberian hams with different salt content (6% vs. 3% of salt w/w) and processing temperature conditions (traditional processing vs. modified processing) was studied using solid-phase microextraction coupled to a direct extraction device (SPME-DED). Traditional processing implied an increase in the temperatures (28 °C) during an intermediate period (drying phase) of the processing, while in the modified process temperature was maintained at 19 °C. Enhanced temperatures in the traditional processing did not increase compounds from lipid oxidation such as hexanal, heptanal, octanal or nonanal. Salt level did not show any effect on volatiles during processing except for 2-pentylfuran during the drying stage (day 177). Although none of the volatile compounds monitored showed significant differences in the final sampling, the ratio between hexanal and octanal plus nonanal, that of hexanal and 3-methylbutanal plus 2-methylbutanal and that of hexanal and γ-octalactone were significantly higher in hams processed under modified system, in which the temperature is lower in the drying stage.     

Volatile compounds present in six types of dry-cured ham from south European countries

A study was conducted to compare the volatile fraction of six types of dry-cured hams from south European countries: (1) France: Bayonne and Corsican hams; (2) Spain: Iberian and Serrano hams; (3) Italy: Parma and Light Italian Country hams. The analysis of the volatile compounds was carried out using a dynamic-head space technique coupled to gas chromatography–mass spectrometry. One hundred and nine compounds were identified and analyzed: aldehydes (15), alcohols (14), ketones (17), esters (11), sulphur compounds (5), nitrogenous compounds (10), terpenes (18), n-alkanes (7) and aromatic and cyclic hydrocarbons (12). The possible formation pathways of these compounds are discussed. The results show that there are important differences among the six types of hams depending on the type of raw material and the technology used, the longer-processing time hams (Iberian and Corsican) being richer in volatile compounds.     

大蒜功能成分研究进展

综述近年来大蒜功能成分方面的研究进展。大蒜功能成分主要分为挥发性化合物和非挥发性化合物两大类,挥发性化合物主要包括硫代亚磺酸酯类及其他脂溶性有机硫化物,非挥发性功能物质主要包括水溶性有机硫化物、类固醇皂苷、皂苷配基、类黄酮类、酚类等。同时,介绍大蒜功能成分的生成途径和蒜氨酸酶的作用、大蒜的药理作用和食用大蒜的可能副作用。     

Volatile compounds in Iberian dry-cured loin

The volatile profile of Iberian dry-cured loin from four different Iberian pig lines (Entrepelado, Lampi?o, Retinto and Torbiscal) and two feeding systems (OUT - fed on acorn and grass-vs.-IND - fed on high oleic acid concentrate) was studied using solid phase microextraction (SPME). 133 volatile compounds were identified and assigned to 16 chemical families. Alcohols were the major group, ethanol being the main compound. The high number of esters detected and the levels of ethanol and acetic acid found, points to an important role of microorganism activity in the formation of volatile compounds in Iberian dry-cured loin. Sulphur compounds, coming mostly from garlic, constituted an important group, with 14 compounds. Significant differences were found among loins from pigs reared in different feeding systems but not among Iberian pig lines. Dry-cured loins from OUT pigs showed higher levels of many compounds derived from lipid oxidation, such as octanoic acid (P=0.000), decanoic acid (P=0.018) or hexanal (P=0.014).     

1H核磁共振结合多元统计方法分析糟鸭加工过程中滋味化合物的变化

在鸭肉原料、糟鸭产品和糟制剂的代谢物中共测出34 种物质,包括氨基酸、糖类、有机酸、碱类、醇类、核苷酸及其衍生物,上述化合物是糟鸭中主要的小分子滋味成分。结果显示,糟鸭加工过程中,氨基酸、醇类、碱类、糖类在煮制、盐腌时下降,糟制中上升;甲酸、次黄嘌呤在整个加工过程中上升,而乳酸、肌酸、肌苷酸和肌苷则持续下降。糟鸭中含量最高的滋味物质是乳酸（4.74 mg/g（干糟产品）;3.30 mg/g（湿糟产品））、天冬氨酸（2.06 mg/g（干糟产品）;3.15 mg/g（湿糟产品））、肌酸（2.78 mg/g（干糟产品）;1.30 mg/g（湿糟产品））、葡萄糖（2.12 mg/g（干糟产品）;3.51 mg/g（湿糟产品））。1H核磁共振能较好地用于糟鸭中非挥发性小分子组分分析,湿糟比干糟过程对滋味化合物含量的影响更显著。     

Effect of malting and roasting of chickpea on functional and nutritional qualities of its protein fractions

Chickpea is gaining importance as a sustainable plant-based protein source due to its high protein content and protein bioavailability. Malting and roasting, the traditional processing techniques, can be used to improve the protein quality of chickpea. The effect of two processing techniques on the water-soluble albumin fraction, salt-soluble globulin fraction, alcohol-soluble prolamin fraction, and alkali-soluble glutelin fraction was studied. Globulin content decreased from 45.85% to 37.08%, whereas the albumin fraction was found to increase from 4.16% to 7.08%, after 6 days of germination. It was observed that malting and roasting resulted in significant changes in the protein quality parameters and decrease in anti-nutritional factors. Tannin content reduced by 53.18% and 40.44%, and the trypsin inhibitor activity reduced by 14.91% and 34.59% after malting and roasting, respectively. The protein efficiency ratio, biological value, and nutritional index improved due to malting and roasting. The biological value of raw chickpea protein was found to be 74.97%, and it increased to 81.89% and 79.27% on malting and roasting, respectively, and protein digestibility values were also increased. Microstructural and diffraction patterns of chickpea flours were examined. Amino acid scores for infants and adults were calculated, and sulphur-containing amino acids were found to be the limiting amino acids in chickpea.     

Correlation Between Protein Hydrolysates and Color During Fermentation of Mucor-Type Douchi

The correlations between the color of douchi and different protein hydrolysates from the post-fermentation period were analyzed. The results showed that peptides had the highest correlation with the color change, while free amino acids were second, which indicated that peptides and free amino acids were more involved in the Maillard reaction. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the 7S component may be more involved in the Maillard reaction during the pre-fermentation of douchi, and that 11S subunits may be more involved in the formation of melanin in the initial stage of post-fermentation. The water-soluble extracts of two douchi samples in the most rapid formation stage of melanin were analyzed by reversed phase-high performance liquid chromatography. The results showed that the hydrophilicity of hydrolysates decreased depending on color. Meanwhile, the amino acid analyses demonstrated that the four amino acids with the maximum loss ratios were all hydrophilic in this stage, which indicated a loss in the hydrophilic components due to their involvement in the Maillard reaction.     

Effect of ripening time and rearing system on amino acid-related flavour compounds of Iberian ham

The evolution of free amino acids and amino acid-derived volatile compounds during the ripening of Iberian ham from pigs reared in a Montanera system (outdoor-based, with acorn and pasture available) and a Pienso system (indoor-based, with a high oleic acid concentrate) was studied. Ripening time influenced significantly all the free amino acids detected (p < 0.05) except for threonine and tyrosine. The total free amino acid content increased significantly from day 120 to day 230 (drying stage) and then the concentration remained almost steady. This marked increase in the free amino acid content matched an increase in the amino acid-derived volatile compounds. The volatile compounds also increased after day 230. Conversely, rearing system had a weak effect on the free amino acid content and on the amino acid-derived volatile compounds. Only glutamic acid was significantly influenced (p = 0.027), and a slight effect on proline and aspartic acid was found (p = 0.051 and p = 0.084, respectively), concentrations being larger in Montanera hams than in Pienso ones. With regard to the amino acid derived volatile compounds, only a significant influence of rearing system on acetaldehyde and on the coelution of 2,6-dimethylpyrazine+dihidro-2(3H)furanone was found. The small differences caused by rearing system confirm the great importance of concentrate formulation.     

Proteolysis in biceps femoris during Jinhua ham processing

Sixty experimental Jinhua hams were processed by a traditional method. The nitrogen fractions and free amino acids in biceps femoris were analyzed. Intense proteolysis was found in ham muscle and totally more than 10% of muscle proteins were degraded during the course of Jinhua ham processing. The proteolytic index of Jinhua ham was between 14 and 20. Both insoluble and soluble proteins were degraded to some degree and the later showed more intense degradation. In the soluble fraction, the percentage of non-protein nitrogen (NPN) increased gradually whereas that of protein nitrogen decreased during processing (P<0.05). However, very small amount of peptides larger than 1kDa was accumulated during the whole course of processing, which proved that intense degradation reactions were also happened to them, especially at the post ripening stage when dramatic decrease of nitrogen fraction from all the peptides larger than 1kDa was found. As a result, more than 90% of the NPN products from muscle proteolysis were free amino acids and peptides of MW less than 1kDa that might make important contribution to Jinhua ham taste and provide precursors for the generation of volatile flavor compounds in ham muscle. The pattern of muscle proteolysis coincided with the reported changes of muscle proteolytic enzymes during processing, seemingly indicating that the enzymes could have played important roles in ham muscle proteolysis.