Impact of Low-temperature Storage on Volatile Flavor Compounds in Prepared Pork Products

[Objectives]This study was conducted to explore the dynamic changes of volatile flavor compounds in prepared pork during storage at different low-temperature conditions.[Methods]Prepared pork was stored at 4,-4 and-18℃.The volatile flavor compounds of prepared pork were determined by solid-phase microextraction-gas chromatography-mass spectrometry(SPME-GC-MS)at days 0,7,14,21 and 28,and relative odor activity value(OAV),principal component analysis(PCA)and cluster analysis(CA)were combined to analyze changes in volatile flavor compounds of prepared pork during storage.[Results]The total number of volatile flavor compounds gradually decreased with the prolongation of the storage period,and OAV analysis identified 22 key flavor compounds(OAV≥1).The results of PCA and CA showed that 2-methyl-1-butanol,1-octen-3-ol,linalool,cineole,hexanal and nonanal were the main key flavor components,and the degree of flavor degradation was low under both superchilling and freezing conditions.After 28 days of storage,the alcohol content in the chilling group was significantly higher than other two groups,and the overall content of volatile flavor compounds was also significantly higher than other two groups,indicating that the-4℃chilling storage was more favorable for maintaining the overall flavor of prepared pork.[Conclusions]This study provides a theoretical basis for finding a better storage method for prepared meat products.

Effect of inoculating mixed starter cultures of Lactobacillus and Staphylococcus on bacterial communities and volatile flavor in fermented sausages

The objective of this study was to explore the effects of the inoculation of mixed starter cultures of Lactobacillus and Staphylococcus(labeled L-S)on microbial community and flavor in fermented sausages during the ripening process.Culture-dependent(colony count)and culture-independent(high-throughput sequencing)methods were employed to evaluate bacterial communities.Volatile compounds were identified by gas chromatography-mass spectrometry,and the results were analyzed by principal component analysis(PCA).The identified bacteria with high relative abundance included Lactobacillus and Pediococcus,and the relative abundances of Leuconostoc and Weissella in fermented sausages were remarkably decreased at the end of the ripening process.At the end of ripening,2-nonenal,tetradecanal,ethylstearate and terpinyl acetate played substantial roles in the flavor development of the L-S fermented sausages.Sensory evaluation showed a high score in the L-S fermented sausages.Sausages can be inoculated with L-S starter culture to improve the safety and flavor of meat products.

Identification of Volatile Compounds in Codfish(Gadus) by a Combination of Two Extraction Methods Coupled with GC-MS Analysis

Codfish is a kind of abyssal fish species with a great value in food industry. However, the flavor of codfish, especially the unpleasant odor, has caused serious problems in its processing. To accurately identify the volatile compounds in codfish, a combination of solid phase micro-extraction(SPME) method and simultaneous distillation extraction(SDE) method was used to extract the volatiles. Gas chromatography-mass spectrometry(GC-MS) along with Kovats indices(KI) and authentic standard compounds were used to identify the volatiles. The results showed that a total of 86 volatile compounds were identified in codfish, of them 24 were extracted by SDE, 69 compounds by SPME, and 10 compounds by both SDE and SPME. Seventy volatile compounds were found to have specific odors, of them 7 typical compounds contributed significantly to the flavor of codfish. Alcohols(i.e.,(E)-2-penten-1-ol and 2-octanol), esters(i.e., ethyl butyrate and methyl geranate), aldehydes(i.e., 2-dodecenal and pentadecanal) contributed the most to fresh flavor while nitrogen compounds, sulphur compounds, furans, as well as some ketones(i.e., 2-hydroxy-3-pentanone) brought unpleasant odor, such as fishy and earthy odor. It was indicated that the combination of multiple extraction methods and GC-MS analysis can enhance the accuracy of identification, and provide a reference for the further study on flavor of aquatic products.

Effects of Diet on the Volatile Flavor and Nutritional Ingredients of Common Octopus(Octopus vulgaris)

Cephalopods are important economic shellfish that have been developed extensively in the coastal water of various countries. Octopus vulgaris is a large-scaled economic cephalopod that is mainly cultured in South China. This study explored the effect of different diets on the volatile flavor and nutritional ingredients of O. vulgaris. Four diets were tested in four groups: Group A(fish(Scomberomorus niphonius)), Group B(crab(Helice tridens tientsinensis Rathbun)), Group C(clam(Mactra veneriformis)), and Group D(squid(Loligo japonica)). Octopus muscles were sampled after 36 days of feeding, and volatile flavor substances(VFSs), fatty acids(FAs), and amino acids(AAs) were detected. Results showed that the VFSs, FAs, and AAs of octopus in the four groups were obviously different. The sum of volatile ketones and aldehydes was higher in Group B than in the other groups, which could present much more flavors. All groups were abundant in unsaturated FAs, including eicosapentaenoic acid(EPA) and docosahexaenoic acid(DHA). In terms of content and variety, the FAs in Group B were more beneficial to human health than those in the other groups. The content of each AA in Group B was basically higher than those in the other groups and was significantly higher than that in Group D(P < 0.05). Comparing the VFSs, FAs, and AAs in samples fed with four kinds of diets, the results indicate that using crab to feed O. vulgaris can achieve better effects on volatile flavor and nutritional ingredients.

Volatile Flavor Composition in Mutton of Ningxia Tan Sheep

[Objective] To analyze the volatile flavor compounds in mutton of different parts of Ningxia Tan sheep. [Method] The volatile flavor compounds in mutton were identified and quantified using the solid phase micro-extraction （SPME） method combined with GC-MS analysis. [ Re- sult ] The proportion of aldehydes in volatile compounds was the highest in the mutton of most parts of Ningxia Tan sheep, but no 4-methyl acid and 4-methyl nonyl acid was detected in the mutton. [ Conclusion]Aldehydes may be important for the volatile flavor of mutton of Ningxia Tan sheep. The study provides a basis for better development and use of Ningxia Tan sheep.

Antibacterial Effect of Lavender （Lavandula） Flavor （Volatile）

The objective of this study was to test the essential oil-emitted flavor （volatile） of lavender by bacteria killing potency using Escherichia coli, methicillin-resistant Staphylococcus aureus （MRSA）, enterohemorrhagic E. coli O157：H7, Pseudomonas aeruginosa and Candida albicans. Antibacterial activity was assessed by creating of the bacterial growth curve in the liquid medium cultivation and the growth inhibition on the agar plate cultivation. Citronellal, one of compounds in Rosa rugose oil, was used as a positive control for comparison in activity. The results showed that lavender and citronellal flavor （volatile） or oil respectively demonstrated bacteria killing effect in both analytical manners. However, P. aeruginosa resisted bacteria killing potency of lavender （citronellal） oil or oil-emitted flavor. It could be concluded that both lavender oil-emitted flavor and oil showed bacteria killing potency. Lavender oil （or oil-emitted flavor） will be expected to apply for the patient waiting room to disinfect in air along with the mental relaxation of the patient.

Effect of Tremella fuciformis polysaccharide on the stalling and flavor of tteok during storage

The effect of Tremella fuciformis polysaccharide(TFP)on the retrogradation property and aroma profile changes of tteok during storage was investigated.Results indicated that addition of TFP significantly increased the stability to thermal and mechanical shearing of starch,decreased short-term retrogradation,the hardness and the retrogradation enthalpy(ΔH)of tteok during storage,but had no significant effect on the amylopectin chain length of tteok.The possible mechanism for the retarding staling effect of TFP is related to the interaction between TFP and starch chains that interferes with the alignment of starch chains.Electronic nose and g as chromatography-mass spectrum(GC-MS)analysis results showed that the difference in the concentrations of volatile compounds and fatty acids of tteoks at different storage time gradually increased with the advancement of storage period.The addition of TFP to tteok inhibited the development of unpleasant volatile compounds,probably by delaying the oxidation and decomposition of lipids and preserving the antioxidant phenolic compounds in tteok,thus slowing down the flavor deterioration of tteok and contributing to flavor maintainace.Overall,this study could help food manufacturers to choose a high-effective and natural polysaccharide to control the retrogradation rate and flavor loss of tteok.

Chemical composition,sensory properties and application of Sichuan pepper(Zanthoxylum genus)

This review summarized the composition of volatile and nonvolatile compounds,the sensory mechanism and the application of Sichuan pepper(Zanthoxylum genus)as a spice and multifunctional food,such as antibacterial,inhibition of inflammation,and antioxidant among others.The aim is to provide a better understanding and potential future in-depth research and application of Sichuan pepper.

Analysis of volatile flavor compounds in top fermented wheat beer by headspace sampling-gas chromatography

Headspace sampling-gas chromatography(HS-GC)coupled with an internal standard method(ISM)was developed to analyze the volatile flavor compounds in top fermented wheat beer in the laboratory.Eight compounds,i.e.acetaldehyde,N-propanol,ethyl acetate,isobutyl alcohol,isoamyl alcohol,isoamyl acetate,ethyl hexanoate and ethyl octanoate were separated and quantified.This method was validated to ensure the quality of the results:the precision was satisfactory with relative standard deviation(RSD)in the range of 1.51%-4.22%,recoveries for all the analytes ranged from 95.15%to 99.85%,and the limits of detection were in the range of 0.0002-0.024 mg/L.Results of real wheat beer samples analyzed using this method showed that the volatile compound concentrations were in the range of 0.08-99.91 mg/L.Results suggested that this method exhibited good reproducibility,selectivity and high precision,and it can be useful for the analysis of routine beer samples.