Effect of intensifying high-temperature ripening on lipolysis and lipid oxidation of Jinhua ham

The orthogonal experiment for fermenting-ripening process was carried out to effectively shorten the process time of Jinhua ham by intensifying high-temperature ripening. Lipolysis and lipid oxidation in the ham were affected by the process time, temperature and salt content during processing. Intensifying high-temperature ripening could accelerate the lipolysis and lipid oxidation. Both saturated and unsaturated free fatty acids (FFAs) were steadily increased with temperature rising (p < 0.01). The daily-increment of total FFAs in the muscle of modern process products was significantly higher than that in the traditional ones (p < 0.01) and kept at a high level through high-temperature ripening. TBARS in ripened hams was remarkably lower than that in traditional products (p < 0.01). These results explained that longtime high-temperature (35-37 °C) ripening could effectively promote lipolysis, decrease TBARS value and accelerate the development of flavor in Jinhua ham.     

Biochemical changes during processing of traditional Jinhua ham

Jinhua ham is the most famous traditional meat product of China and one of the most famed dry-cured hams in the world. Its processing consists of six stages: green ham preparation, salting, washing and sun-drying and shaping, ripening, and post-ripening. Intense proteolysis and lipolysis occur during processing period. As a result, the content of free amino acids in final ham products is 14-16 times that of green ham, and 191 volatile compounds have been identified during processing, which make a major contribution to the flavor of Jinhua ham.     

Pig sire type and sex effects on carcass traits,meat quality and physicochemical and sensory characteristics of Serrano dry‐cured ham

This study demonstrates that improvements in animal line selection by breeding enterprises exert a strong effect on carcass traits, meat quality and sensory characteristics of Serrano dry‐cured ham. A total of 461 pigs from the offspring of a Duroc (DU) × Landrace (LD) sow mated with two DU boars and a DU × Large White (LW) boar from three breeding enterprises were evaluated. The two DU terminal sires were significantly different (P < 0.05) in carcass conformation, backfat thickness, ham and loin yields, raw ham traits, myoglobin concentration and total pigments formed during the curing process; in addition, the two lines provided different percentages of hams (54 vs 91%) with sufficient subcutaneous fat and weight to manufacture dry‐cured Serrano hams using a slow ripening process (11 months). The DU × LW sire had the best carcass and ham traits from an economic standpoint and obtained highest scores for sensory characteristics of Serrano ham evaluated by a trained panel test; furthermore, this line provided 84% of total hams suitable for manufacturing Serrano hams by a slow process. When the sex effect was analysed, carcass and ham traits of females were more favourable, but females presented a higher incidence of pale, soft and exudative (PSE) meat and a lower percentage of hams with sufficient subcutaneous fat and weight to produce Serrano hams using a slow ripening process (61% for females and 91% for castrates). On the other hand, castrates provided Serrano hams cured by a slow procedure with better organoleptic characteristics than females. Right and left hams were similar. Copyright © 2005 Society of Chemical Industry     

Proteolysis and Flavor Characteristics of Serrano Ham Processed under Different Ripening Temperature Conditions

Physicochemical, proteolysis and sensory characteristics of Serrano hams processed under low, medium and high ripening temperature conditions (RTC), with respective average temperatures of 9.3, 14.3, and 19.1 °C, were determined throughout a 15‐mo period. In addition, quantitative relationships among variables were calculated. Medium and high RTC hams showed lower moisture contents and lower levels of low‐ and high‐ionic‐strength soluble proteins than low RTC hams. At 15 mo, aldolase was the most abundant low‐ionic‐strength soluble protein and actin the most abundant high‐ionic‐strength soluble protein in all hams while creatine kinase was no longer detected and H‐meromyosin was detected only in low and medium RTC hams. Levels of all the molecular‐weight peptide fractions increased during ripening, with higher factors of increase for the fractions of lower molecular weight. Total free amino acids were at significantly higher concentrations in medium and high RTC hams than in low RTC hams from month 7 onwards. The correlations of flavor preference and flavor intensity with ripening time, thermal integral, total free amino acids and most individual free amino acids were highly significant, while raw‐meat taste was negatively correlated with all those variables. From month 5 to month 9 of ripening, development of a high quality flavor evolved more rapidly in medium RTC hams, flavor intensity increased at a faster rate in high RTC hams and raw‐meat taste declined more rapidly in medium and high RTC hams. Medium and high RTC may be applied to accelerate the ripening process of Serrano ham without impairing flavor preference.     

肌肉非蛋白氮和游离氨基酸在金华火腿加工过程中的变化

以60只浙江兰溪当地杂交猪后腿为原料,按传统工艺加工金华火腿,分析了股二头肌中非蛋白氮(Non-proteinnitrogen,NPN)和游离氨基酸(Freeaminoacids,FAA)浓度随加工时间而变化的规律。结果表明,肌肉中的NPN和FAA含量都随金华火腿加工进程逐渐升高;NPN在后熟期和晒腿期间升高速度最快,而FAA在成熟过程中升高最快,成品火腿的蛋白质降解指数在14～20之间;成品火腿中的FAA占NPN的70%以上,其中以Arg、Glu、Leu、Lys、Ala和Val等含量较高。FAA总含量比腌制前提高13.8倍,火腿中大部分FAA浓度为腌制前的10～20倍,其中增加比例较大的FAA有Lys、Asp、Ser、Tyr和Ile等。火腿中大部分游离氨基酸的浓度多倍于其感觉阈值,因此可能对火腿风味的形成有重要贡献。     

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.     

Proteolysis,Texture, and Sensory Characteristics of Serrano Hams from Duroc and Large White Pigs during Dry‐Curing

Proteolysis, texture, physicochemical, and sensory characteristics of Serrano hams from Duroc and Large White pigs at 5, 7, 9, 12, and 15 m of curing (3 hams per breed per curing time) were investigated. Higher concentrations of some sarcoplasmic and myofibrillar proteins, peptides with molecular mass in the ranges 3700 to 12000 Da, 700 to 2000 Da, and below 450 Da, and total free amino acids were recorded for Large White hams, while hydrophobic peptides were at higher levels in Duroc hams. A 40 kDa peak in the low‐ionic‐strength soluble protein fraction and 2 peaks of 40 and 45 kDa in the high‐ionic‐strength soluble protein fraction found only in Duroc hams could be of use in discriminating products from different breeds. Physicochemical and textural characteristics of both types of hams evolved similarly during curing and differences in organoleptic traits between breeds were negligible. Flavor intensity and flavor quality of hams were strongly correlated to curing time, with r² values over 0.95 for flavor intensity and over 0.90 for flavor quality, and to the concentration of total free amino acids, with r² values over 0.90 for both flavor intensity and flavor quality. The sensory evaluation scores of Duroc hams, at least as high as those of Large White hams, make the production of high‐quality Serrano ham from pure breed Duroc pigs feasible. Practical Application: Duroc breed crosses are advantageous in the production of dry‐cured hams, resulting in higher marbling, enhanced flavor and lower processing losses, but the characteristics of pure breed Duroc hams have not been investigated. The similar evolution of the compositional, proteolytic, textural, and sensory characteristics of Serrano hams from Duroc and Large White pigs during dry‐curing recorded in the present work makes the production of high‐quality dry‐cured hams from pure breed Duroc pigs feasible. Three protein peaks found only in Duroc hams can be of use to discriminate products from different breeds.     

采用同时蒸馏提取法分析不同加工时期金华火腿香味成分

腌制时间对金华火腿的风味与质量十分重要 ,文中采用同时蒸馏提取法比较了成熟火腿(发酵 1a)和生火腿 (未经发酵 )中的风味成分 ,分别得到了 77种和 62种化合物。结果显示 ,成熟火腿中的醛醇类物质 (3 4种 )尤其是烯醛和烯醇的种类和数量明显多于生火腿 (1 5种 )。同时 ,文中还讨论分析了各类组分及它们的风味贡献。     

基于智能感官与人工感官评价的中国三大干腌火腿风味特性分析

以我国三大干腌火腿金华火腿、宣威火腿和如皋火腿三个不同年份或等级的火腿为研究对象,分别采用人工感官评价和电子鼻、电子舌智能感官技术分别对香气与滋味进行研究。人工感官评价结果显示,肉香味、腌制味和油脂香是三大火腿的特征香气,如皋和金华火腿中2年/优级和3年陈/特级的干腌火腿较于1级/1年陈具有更加浓郁的肉香,而1年陈/1级火腿的酸味更为明显。电子鼻和电子舌数据的主成分分析(Principal component analysis,PCA)结果表明,不同干腌火腿样品均能实现良好区分。1年陈/1级与2年/优级、3年陈/特级干腌火腿气味轮廓相差较远,金华火腿与宣威2、3年陈的火腿香气和滋味轮廓均比较接近。采用软独立建模分类法(Soft independent modeling class analogy,SIMCA)构建了干腌火腿的判别模型,以三个产地最优干腌火腿为标准样品的等级鉴别模型能够实现对其他年份干腌火腿的有效判别。说明不同年份的火腿风味变化呈现一定规律,可利用智能感官技术对火腿进行快速有效的等级鉴别。     

Changes in the volatile flavour components of Jinhua ham during the traditional ageing process

Changes in volatile flavour compounds of Jinhua ham were studied during the traditional ageing process of sun‐drying, loft‐ageing and post‐ageing. About seventy‐eight volatile compounds were tentatively identified, including aldehydes (ten to fifteen), carboxylic acids (eight to ten), alcohols (thirteen to fourteen), ketones (eight), esters (eight to ten), aromatic hydrocarbons (five), sulphur‐containing compounds (two to three) and pyrazines (zero to four) which were the main components. The percentage content of aldehydes and ketones reduced over time as the temperature rose with each stage of the process, whereas alcohols, carboxylic acids, esters, pyrazines and sulphur‐containing compounds increased gradually. Jinhua ham's high‐temperature maturating process (40 days at 30–37 °C) made the percentage content of carboxylic acids arising from Maillard reactions markedly increase (from sun‐dried ham 8.45% to fully aged ham 19.23%). This was the most obvious difference between Jinhua ham and the Mediterranean dry‐cured hams, and was the main factor leading to the unique flavour of Jinhua ham.     

Contribution of a selected fungal population to the volatile compounds on dry-cured ham

Dry-cured ham is obtained after several months of ripening. Different fungi strive on the surface, including toxigenic molds. Proteolysis and lipolysis by the endogenous and microbial enzymes seem to play a decisive role in the generation of flavor precursors in dry-cured meat products. In addition, fungi show a positive impact on the volatile compounds of ripened pork loins. However, the contribution of the fungal population to flavor formation in dry-cured ham remains unclear. One selected strain each of Penicillium chrysogenum and Debaryomyces hansenii was inoculated as starter cultures on dry-cured ham. Volatile compounds extracted by solid phase micro-extraction technique were analyzed by gas chromatography/mass spectrometry. A trained panel evaluated flavor and texture of fully ripened hams. The wild fungal population on non-inoculated control hams correlates with higher levels of short chain aliphatic carboxylic acids and their esters, branched carbonyls, branched alcohols, and some sulfur compounds, particularly at the outer muscle. Conversely, P. chrysogenum and D. hansenii seem to be responsible for higher levels of long chain aliphatic and branched hydrocarbons, furanones, long chain carboxylic acids and their esters. The very limited impact of P. chrysogenum on pyrazines in inoculated hams can be due to the activity of the yeast. Lower levels for some of the more volatile linear carbonyls at the ham surface suggest an anti-oxidant effect by micro-organisms. The differences in volatile compounds did not show a neat impact on flavor in the sensorial analysis. Nonetheless, inoculated hams got a better overall acceptability, which has to be attributed to their improved texture. The lower toughness of inoculated hams is a direct consequence of an early settling of a highly proteolytic mold. Thus, the use of selected fungi as starter cultures may be useful to obtain high-quality and safe dry-cured ham.     

金华火腿中挥发性风味物质形成过程及变化规律研究

以60只杂交猪后腿为原料,按照传统工艺加工金华火腿,采用固相微萃取(SPME)技术和气谱-质谱联用仪(GC-MS)分离、鉴定技术,研究了金华火腿股二头肌中挥发性风味化合物的形成变化规律。从6个不同加工时期的样品中共鉴定出191种物质,包括43种烃、31种醛、24种酮、21种酯、19种醇、17种羧酸、16种杂环化合物、5种内酯、5种含氯化合物、4种含硫化合物、2种酚、2种酸酐、1种酰胺和1种醚。其中醛类、醇类、烃类、酮类、酸类和酯类化合物含量较高,但各类风味物质的化合物种类和含量的变化规律各不相同。随着加工进行,肌肉中的挥发性化合物种类逐渐增多,但化合物总含量以晒腿结束和成熟中期最高。研究结果表明,与国外干腌火腿相比,金华火腿成品中羧酸、支链化合物、芳香族化合物及杂环化合物种类和含量较多,可能是金华火腿的风味特征。     

Effects of phosphine and methyl bromide fumigation on the volatile flavor profile and sensory quality of dry cured ham

In separate experiments, randomized complete block designs with three replications were utilized to evaluate the effects of phosphine (PH₃) (0, 200 and 1000 ppm for 48 h) and methyl bromide (MB) (0, 4, 8, 16, and 32 mg/L for 48 h) fumigation concentration on the volatile flavor compound concentrations in dry cured ham. Minimal differences existed (P > 0.05) in the presence and concentration of aroma active compounds in both PH₃ and MB fumigated hams but sulfur and oxidation compounds were more prevalent (P < 0.05) in the fumigated treatments when compared to the control. As phosphine fumigation concentration increased, the residual concentration of phosphine also increased in the hams (P < 0.05), but all samples contained levels that are lower than the legal limit of phosphine allowed in stored food products (0.01 ppm) in the United States. A triangle test (n = 56) indicated that consumers could not discriminate (P > 0.75) between the control hams and those that were fumigated with PH₃. Minimal aroma/flavor differences existed among MB, PH3 and control hams, and dry cured ham that was fumigated with PH₃ was safe for consumption based on residual phosphine concentrations in the meat tissue.     

不同地域典型干腌火腿肌原纤维蛋白的氧化特性及体外消化性对比

为比较几种典型干腌火腿的可消化吸收性,以巴马火腿、金华火腿、宣威火腿、帕尔玛火腿为原料,研究4 种干腌火腿的肌原纤维蛋白表面疏水性、巯基和二硫键含量、超微结构、蛋白降解程度、消化前后粒径及体外消化率。结果表明：金华火腿肌原纤维蛋白的表面疏水性显著高于巴马、宣威、帕尔玛火腿（P＜0.05）。微观结构分析显示金华火腿肌原纤维蛋白交联和聚集程度最低,肌原纤维排布更为伸展;帕尔玛火腿聚集程度最大,呈现明显聚集状。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳谱图显示金华火腿肌原纤维蛋白在体外消化过程中大幅降解,促进了肌原纤维蛋白粒径的降低。体外模拟消化结果表明,经胃蛋白酶、胰蛋白酶及α-凝乳蛋白酶作用后,金华火腿肌原纤维蛋白水解速率最高（P＜0.05）;帕尔玛火腿肌原纤维蛋白水解速率最低（P＜0.05）。这表明疏水基团的暴露和蛋白结构的伸展为消化酶提供了更多的识别位点,促进了金华火腿中肌原纤维蛋白的水解。综上,肌原纤维蛋白的氧化程度显著影响蛋白的体外消化率。     

Compositional and degradative changes during the manufacture of dry‐cured ‘lacón’

The gross and mineral composition, the main physicochemical parameters, the protein extractability and the proteolytic (nitrogen fractions and free amino acids) and lipolytic (acidity index and free fatty acids) changes were studied throughout the manufacturing process of five batches of dry‐cured ‘lacón’, a traditional Spanish meat product made from the fore‐ham of the pig following a similar technological process to that of dry‐cured ham. The main compositional characteristics of this product are the high NaCl content and the low moisture content at the end of the curing process. The pH remained fairly stable (around 6) throughout the whole process and a fall in a_w was observed, reaching very low (0.767 ± 0.052) final average values. It was noted that 76% of the sarcoplasmic and 83% of the myofibrillar proteins became insoluble during the manufacturing process. The values of the different nitrogen fractions increased in a significant manner during manufacture, reaching low final values that indicate that ‘lacón’ undergoes a low level of proteolysis in comparison with other products manufactured by similar technologies. The high NaCl content and the intense dehydration suffered during the manufacturing process appear to be the principal causes of this reduced protein degradation. In accordance with the limited increase in the α‐amino acidic nitrogen during ripening, the total free amino acid content increased slightly but significantly from average values of 4371 mg kg^?1 dry matter in fresh pieces to average values of 13 020 mg kg^?1 dry matter in pieces at the end of the ripening process. The profile of free amino acids in the final product was similar to that observed by other authors in dry‐cured ham. The acidity of the fat increased by a factor of five. The final average values (49.9 g oleic acid kg^?1) were lower than those determined in dry‐cured ham, which indicates that ‘lacón’ undergoes less lipolysis during the ripening process than dry‐cured ham. C18 : 1, C18 : 2 and C16 were the most intensively released fatty acids during curing. The profile of free fatty acids in the end product was in agreement with that observed by other authors in dry‐cured ham. Copyright © 2003 Society of Chemical Industry     

Changes in the composition and sensory properties of Croatian cheese in a lamb skin sack (Sir iz mišine) during ripening

Croatian traditional cheese, which ripens in a lamb skin sack, was studied to determine compositional, biochemical and sensory changes over 60 days of ripening. The ripening time had a significant effect on the chemical, biochemical and sensory parameters, particularly on the medium‐ and long‐chain free fatty acids (P < 0.05) and total FFAs (P < 0.001). At the end of ripening palmitic, oleic and stearic acids were the predominant FFAs. Cheese ripened for more than 45 days was less acceptable to consumers as a consequence of extensive proteolysis and lipolysis. Therefore, ripening for more than 45 days, which is commonly practised by cheesemakers, is not recommended.     

Sulfuryl fluoride fumigation effects on the safety,volatile composition,and sensory quality of dry cured ham

A randomized complete block design with three replications was utilized to evaluate the effects (P < 0.05) of various fumigation concentrations of sulfuryl fluoride (SF) (0, 12, 24, 36 and 72 mg/L) on the fluoride, sulfuryl fluoride, and volatile flavor compound concentrations in dry cured ham. Fluoride and SF concentrations increased (P < 0.05) in dry cured hams as SF fumigation concentration increased, but all samples contained fluoride and SF concentrations below the legal limits of 20 and 0.01 ppm, respectively. Minimal differences existed (P > 0.05) in the presence and concentration of aroma active compounds, but oxidation compounds were slightly more prevalent (P < 0.05) in the 72 mg/ml treatment when compared to the control. A triangle test (n = 54) indicated that consumers could not discern (P > 0.75) between hams that were fumigated with SF at 0 and 36 mg/ml. This study revealed that there were minimal aroma/flavor differences among the ham treatments between 0 and 36 mg/ml, and that dry cured ham that was fumigated with SF was safe and met legal requirements for consumption.     

Changes of alanyl aminopeptidase activity and free amino acid contents in biceps femoris during processing of Jinhua ham

Sixty experimental Jinhua hams were processed by a traditional method. The potential alanyl aminopeptidase (AAP) activity in biceps femoris was determined. The effects of temperature, salt content, sodium nitrate content and pH on muscle AAP were evaluated using response surface methodology. Porcine muscle was found to possess very strong potential AAP activity that decreased gradually during processing from 201,635 U g⁻¹ before salting to 6147 U g⁻¹ after aging. Temperature, pH and salt content had significant exponential effects on AAP activity (P < 0.001). Both temperature and salt content interacted with pH in their effects on AAP activity (P < 0.01). However, 0–50 mg L⁻¹ sodium nitrate had no detectable effect on AAP activity (P > 0.05). The regression model showed muscle AAP maintaining its activity all through Jinhua ham processing, indicating that muscle AAP may generate free amino acids during the processing and storage of Jinhua ham. The concentrations of free amino acids increased significantly (P < 0.05) during Jinhua ham processing, except for arginine and cystine. The concentrations of most free amino acids were 5–20 times higher in the final product than in hams before salting. Final concentrations exceeded thresholds for sensory detection, thus implicating an important role of free amino acids in the determination of Jinhua ham flavor.     

基于R-型聚类分析的金华火腿主导风味的识别

为了弄清金华火腿的主导风味成分,随机取5条不同等级金华火腿的股二头肌为样品,利用固相微萃取(SPME)和气质联用(GC/MS)系统进行风味成分研究。结果发现,四级火腿中共检测到116种成分,在1-4级火腿中分别检出84,84,83和92种成分。经过设定类群数目进行R-型聚类分析,最终得到13种主导风味成分,分别为:丁酸、已醛、丁酸乙酯、乙酸、戊醛、2-甲基丁醛、3-甲基丁醛、丙酮、3-甲基丁酸、2,3-丁二醇、2-甲基丙酸、苯酚和丙酸。     

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