Volatile compounds of Cantonese sausage released at different stages of processing and storage

Evolution of Volatile Compounds and Spoilage Bacteria in Smoked Bacon during Refrigeration Using an E-Nose and GC-MS Combined with Partial Least Squares Regression

The changes in the concentration of volatile organic compounds (VOCs) and biogenic amines (BAs) in smoked bacon during 45-day refrigerated storage is investigated using solid-phase micro-extraction coupled with gas chromatography-mass spectrometry and high-performance liquid chromatography. In total, 56 VOCs and 6 BAs were identified and quantified. The possible pathways leading to their formation are analyzed and considered as the potential signs of microbial activity, especially by specific spoilage microorganisms (SSOs). Leuconostoc and Lactobacillus, which levels increased markedly with the extension of storage time, were recognized as SSOs. An electronic nose (e-nose) was employed to determine the changes in concentration of the odor components per sample present within half an hour. Partial least squares regression was then carried out to analyze the correlation between SSO growth, metabolite concentration, BA accumulation, and e-nose response. The results show that ten VOCs (ethanol, 2-furanmethanol, 1-hexanol, 1-propanol, phenol, 2-methoxyphenol, acetic acid, 3-ethyl-2-cyclopenten-1-one, furfural, and ethyl hexanoate) and three BAs (putrescine, cadaverine, and tyramine) can be associated with the growth of SSOs. Thus, they can be adopted as potential indicators to evaluate and monitor the quality of the bacon and develop appropriate detection methods. E-noses can used to recognize odors and diagnose quality of bacon.

Grading of Chinese Cantonese Sausage Using Hyperspectral Imaging Combined with Chemometric Methods

Fast and accurate grading of Chinese Cantonese sausage is an important concern for customers, organizations, and the industry. Hyperspectral imaging in the spectral range of 874–1734 nm, combined with chemometric methods, was applied to grade Chinese Cantonese sausage. Three grades of intact and sliced Cantonese sausages were studied, including the top, first, and second grades. Support vector machine (SVM) and random forests (RF) techniques were used to build two different models. Second derivative spectra and RF were applied to select optimal wavelengths. The optimal wavelengths were the same for intact and sliced sausages when selected from second derivative spectra, while the optimal wavelengths for intact and sliced sausages selected using RF were quite similar. The SVM and RF models, using full spectra and the optimal wavelengths, obtained acceptable results for intact and sliced sausages. Both models for intact sausages performed better than those for sliced sausages, with a classification accuracy of the calibration and prediction set of over 90%. The overall results indicated that hyperspectral imaging combined with chemometric methods could be used to grade Chinese Cantonese sausages, with intact sausages being better suited for grading. This study will help to develop fast and accurate online grading of Cantonese sausages, as well as other sausages.

Evaluation of lipid oxidation of Chinese-style sausage during processing and storage based on electronic nose

A portable electronic nose was used for extracting flavour fingerprint map of Chinese-style sausage during processing and storage, in parallel with detection of acid value (AV) and peroxide value (POV) for evaluating lipid oxidation. Sausage samples during processing and storage were divided into three and five quality phases, respectively. After comparison of sensors response to lipid oxidation, optimal sensor array was determined. Several classification and regression models were developed to classify samples into their respective quality phase and predict lipid oxidation using full and optimal sensor array. Results indicated classification accuracy for sausage samples were, respectively, above 95% and 82% during the processing and storage. For support vector machine (SVM) and artificial neural networks (ANN) regression models, good performance in predicting AV and POV were obtained, with the coefficients of determination (R²s) >0.914 and 0.814 during processing and storage, respectively. Thus, E-nose demonstrated acceptable feasibility in evaluating the degree of lipid oxidation of Chinese-style sausage during processing and storage.

Identification of aroma volatiles and understanding 2-acetyl-1-pyrroline biosynthetic mechanism in aromatic mung bean (Vigna radiata (L.) Wilczek)

Mung bean having high food value and easily digestible proteins, is one of the socioeconomically important crop of India. Among the varied cultivars, Sona mung is having aroma and hence popularly cultivated in the pockets of Ganga river basin at Bhutnir char village of Malda District in the West Bengal state. In the present study, aroma volatiles with special reference to 2-acetyl-1-pyrroline (2AP) were analyzed using HS-SPME-GCMS from Sona mung bean and compared with non-scented mung bean (PHULE M-9339). 26 volatiles in seeds of Sona mung and 20 in non-scented mung bean were identified, in which 3,7-dimethyl-6-octenal, (2E)-2-decen-1-ol, 2-ethyl-1-dodecanol and 3,5,5-trimethyl-2-cyclohexene-1-one are first time reported. 0.19 ± 0.001 ppm 2AP was recorded in Sona mung seeds whereas it was not detected in non-scented mung bean. PCA analysis indicated that 2AP, octanal, 1 pentanol, decanal, phenylmethanol and 2-nonen-1-ol were the major contributors in the aroma of Sona mung bean. The significantly higher level proline, methylglyoxal and lower level of BADH2 transcript were detected in Sona mung than non-scented mung, suggesting similar 2AP biosynthesis mechanism in Sona mung bean as reported in scented rice, sorghum and soybean.

An Updated Review of Meat Authenticity Methods and Applications

Adulteration of foods is a serious economic problem concerning most foodstuffs, and in particular meat products. Since high-priced meat demand premium prices, producers of meat-based products might be tempted to blend these products with lower cost meat. Moreover, the labeled meat contents may not be met. Both types of adulteration are difficult to detect and lead to deterioration of product quality. For the consumer, it is of outmost importance to guarantee both authenticity and compliance with product labeling. The purpose of this article is to review the state of the art of meat authenticity with analytical and immunochemical methods with the focus on the issue of geographic origin and sensory characteristics. This review is also intended to provide an overview of the various currently applied statistical analyses (multivariate analysis (MAV), such as principal component analysis, discriminant analysis, cluster analysis, etc.) and their effectiveness for meat authenticity.

Relationship between sensory attributes and volatile compounds of polish dry-cured loin

Objective

The aim of this work was to determine the relationship between objective sensory descriptors and volatile flavour compound composition of Polish traditional dry-cured loin.

Methods

The volatile compounds were investigated by using solid phase microextraction (SPME) and gas chromatography–mass spectrometry (GC–MS). For sensory assessment, the quantitative descriptive analysis (QDA) method was used.

Results

A total of 50 volatile compounds were found and assigned to 17 chemical families. Most of the detected volatile compounds derived from smoking, lipid oxidative reactions and seasoning (46.8%, 21.7%, and 18.9%, respectively). The dominant compounds were: aromatic hydrocarbon (toluene); alkanes (hexane, heptane, and 2,2,4-trimethylpentane); aldehyde (hexanal); alcohol (2-furanmethanol); ketone (3-hydroxy-2-butanone); phenol (guaiacol); and terpenes (eucalyptol, cymene, γ-terpinen, and limonene). Correlation analysis showed that some compounds derived from smoking were positively correlated with the intensity of cured meat odour and flavour and negatively with the intensity of dried meat odour and flavour, while terpenes were strongly correlated with odour and flavour of added spices.

Conclusion

The analysed dry-cured loins were characterized by specific and unique sensory profile. Odour and flavour of studied loins was mainly determined by volatile compounds originating from smoking, seasoning and lipid oxidation. Obtained results suggest that smoking process is a crucial stage during Polish traditional dry-cured loins production.

Binding of aroma compounds with myofibrillar proteins modified by a hydroxyl-radical-induced oxidative system

The objective of this study was to investigate the influence of oxidation-induced structural modifications of myofibrillar protein on its binding ability with aroma compounds such as 2-methyl-butanal, methional, 2-pentanone, 2-heptanone, and nonanal. A method using solid-phase microextraction (SPME) combined with gas chromatography/mass spectrometry (GC/MS) was used to determine the corresponding binding ability. The binding with aroma compounds was found to be strongly affected by the oxidation levels of proteins, probably due to the varying modifications in protein structure and surface. Incubation with oxidants around or below 1 mM mainly caused the refolding of protein structure and accelerated the protein aggregation, which reduced the affinity of the aroma compounds, thus decreasing the binding ability. Nevertheless, treatment with oxidants over 2.5 mM would cause protein reaggregation and partial degradation, and thus, the subsequent modification of protein surface properties. The aggregated protein with wrinkled surfaces favored the hydrophobic interactions with aroma compounds, forming the protein-aroma compound complex, thus enhancing the resultant binding ability as evidenced by fluorescence quenching and SPME-GC/MS analysis.

A novel method for beef potentiator preparation and identification of its characteristic aroma compounds

BACKGROUND

Beef potentiator (BP) is the most popular savoury flavour and regarded as the soul of the modern food industry. In this work, BP was prepared by a novel method with Aspergillus oryzae and Aspergillus niger (BPSF). Three other BPs prepared using commercial enzymes (Protamex, Flavourzyme and papain; BPCEs) were used as controls to investigate its aroma characteristics and related compounds.

RESULTS

Sensory evaluation showed that BPSF possessed more favourable and distinctive sauce-like, meat-like, roast and alcoholic attributes when compared with BPCEs. Significantly higher contents (peak areas) and proportions of pyrazines, pyrroles, sulfurous compounds and alcohols in BPSF were responsible for its sensory characteristics, and most of these aroma compounds were derived from microbial metabolism during beef koji preparation and the Maillard reaction.

CONCLUSION

BP prepared by synergistic fermentation with A. oryzae and A. niger is a potential alternative for BP preparation.

Effect of koji fermentation on generation of volatile compounds in soy sauce production

The generation of aroma compounds and the changes in sensory characteristics through the soy sauce koji fermentation were investigated to evaluate the crucial impact of the koji fermentation on soy sauce aroma. The sensory analysis showed a marked increase in ‘musty’ and ‘soy sauce‐like’ odours, whereas the beany attribute decreased significantly during koji fermentation. Aldehydes and alcohols were the major volatile classes present in the koji samples. Gas chromatography–olfactometry was used to identify the aroma‐active compounds in harvested koji, and the results showed that 1‐octen‐3‐ol, 3‐octanol, (E)‐2‐octenal, di‐epi‐α‐cedrene, benzeneacetaldehyde and 3‐(methylthio)‐propanal exhibited the greatest aroma intensities in harvest koji. Moreover, relative contents of (E)‐2‐octenal, benzeneacetaldehyde, 3‐(methylthio)‐propanal and 2‐phenylpropenal were found to be positively related to ‘musty’ and ‘soy sauce‐like’ odours. Results from principal component analysis showed that the growth and sporulation of Aspergillus oryzae had the important impacts on the volatile evolution.

Ion mobility spectrometry for detection of skin volatiles

Volatile organic compounds (VOCs) released by humans through their skin were investigated in near real time using ion mobility spectrometry after gas chromatographic separation with a short multi-capillary column. VOCs typically found in a small nitrogen flow covering the skin are 3-methyl-2-butenal, 6-methylhept-5-en-2-one, sec-butyl acetate, benzaldehyde, octanal, 2-ethylhexanol, nonanal and decanal at volume fractions in the low part per billion-(ppb) range. The technique presented here may contribute to elucidating some physiological processes occurring in the human skin.

Dependence of exhaled breath composition on exogenous factors, smoking habits and exposure to air pollutants

Non-invasive disease monitoring on the basis of volatile breath markers is a very attractive but challenging task. Several hundreds of compounds have been detected in exhaled air using modern analytical techniques (e.g. proton-transfer reaction mass spectrometry, gas chromatography-mass spectrometry) and have even been linked to various diseases. However,the biochemical background for most of compounds detected in breath samples has not been elucidated; therefore, the obtained results should be interpreted with care to avoid false correlations. The major aim of this study was to assess the effects of smoking on the composition of exhaled breath. Additionally, the potential origin of breath volatile organic compounds (VOCs) is discussed focusing on diet, environmental exposure and biological pathways based on other's studies. Profiles of VOCs detected in exhaled breath and inspired air samples of 115 subjects with addition of urine headspace derived from 50 volunteers are presented. Samples were analyzed with GC-MS after preconcentration on multibed sorption tubes in case of breath samples and solid phase micro-extraction (SPME) in the case of urine samples. Altogether 266 compounds were found in exhaled breath of at least 10% of the volunteers. From these, 162 compounds were identified by spectral library match and retention time (based on reference standards). It is shown that the composition of exhaled breath is considerably influenced by exposure to pollution and indoor-air contaminants and particularly by smoking. More than 80 organic compounds were found to be significantly related to smoking, the largest group comprising unsaturated hydrocarbons (29 dienes, 27 alkenes and 3 alkynes). On the basis of the presented results, we suggest that for the future understanding of breath data it will be necessary to carefully investigate the potential biological origin of volatiles, e.g., by means of analysis of tissues, isolated cell lines or other body fluids. In particular, VOCs linked to smoking habit or being the results of human exposure should be considered with care for clinical diagnosis since small changes in their concentration profiles(typically in the ppt(v)–ppb(v) range) revealing that the outbreak of certain disease might be hampered by already high background.

Effect of cooking temperatures on protein hydrolysates and sensory quality in crucian carp (Carassius auratus) soup

Cooking methods have a significant impact on flavour compounds in fish soup. The effects of cooking temperatures (55, 65, 75, 85, 95, and 100 °C) on sensory properties and protein hydrolysates were studied in crucian carp (Carassius auratus) soup. The results showed that the soup prepared at 85 °C had the best sensory quality in color, flavour, amour, and soup pattern. Cooking temperature had significant influence on the hydrolysis of proteins in the soup showed by SDS-PAGE result. The contents of water soluble nitrogen (WSN) and non-protein nitrogen (NPN) increased with the cooking temperature, but the highest contents of total peptides and total free amino acids (FAA) were obtained at the cooking temperature of 85 °C. The highest contents of umami-taste active amino acid and branched-chain amino acids were also observed in the 85 °C sample. In conclusion, a cooking temperature of 85 °C was preferred for more excellent flavor and higher nutritional value of crucian carp soup.