Determination of volatile marker compounds in raw ham using headspace-trap gas chromatography

A new HS-SPME-GC-MS analytical method to identify and quantify compounds responsible for changes in the volatile profile in five types of meat products during aerobic storage at 4 °C

Nowadays, it is important to monitor the freshness of meat during storage to protect consumers' health. Volatile organic compounds (VOCs) are responsible for odour and taste of food, and they give an indication about meat quality and freshness. This study had the aim to seek and select potential new markers of meat spoilage through a semi-quantitative analysis in five types of meat (beef, raw and baked ham, pork sausage and chicken) and then to develop a new quantitative analytical method to detect and quantify potential markers on five types of meat simultaneously. Firstly, a new headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) method was developed to evaluate the volatile profile of five types of meat, preserved at 4 °C for 5 days. Among the 40 compounds identified, 15 were chosen and selected as potential shelf-life markers on the basis of their presence in most of meat samples or/and for their constant increasing/decreasing trend within the sample. Afterwards, a quantitative HS-SPME-GC-MS analytical method was developed to confirm which VOCs can be considered markers of shelf-life for these meat products, stored at 4 °C for 12 days. Some of the compounds analyzed attracted attention as they can be considered markers of shelf-life for at least 4 types of meat: 1-butanol, 3-methylbutanol, 1-hexanol, 2-nonanone, nonanal, 1-octen-3-ol and linalool. In conclusion, in this study a new quantitative HS-SPME-GC-MS analytical method to quantity 15 VOCs in five types of meat was developed and it was demonstrated that some of the compounds quantified can be considered markers of shelf-life for some of the meat products analyzed.

Recent advances and challenges in the interaction between myofibrillar proteins and flavor substances

Myofibrillar proteins are an important component of proteins. Flavor characteristics are the key attributes of food quality. The ability of proteins to bind flavor is one of their most fundamental functional properties. The dynamic balance of release and retention of volatile flavor compounds in protein-containing systems largely affects the sensory quality and consumer acceptability of foods. At present, research on flavor mainly focuses on the formation mechanism of flavor components, while there are few reports on the release and perception of flavor components. This review introduces the composition and structure of myofibrillar proteins, the classification of flavor substances, the physical binding and chemical adsorption of myofibrillar proteins and volatile flavor substances, as well as clarifies the regulation law of flavor substances from the viewpoint of endogenous flavor characteristics and exogenous environment factors, to provide a theoretical reference for the flavor regulation of meat products.

The Characterization of the Key Aroma Compounds in Non-Smoked Bacon by Instrumental and Sensory Methods

The aroma profiles in non-smoked bacon were investigated via GC-O-MS, GC × GC-TOFMS, and GC-IMS. GC-O-MS is advantageous for detecting aldehydes. GC × GC-TOFMS is more sensitive to hydrocarbons and alcohols, while GC-IMS detects a balanced range of categories. Only 9 of the 239 detected volatiles were identifiable by all three methods. Therefore, the combination of all three methods proved to be the most effective way to comprehensively analyze the aroma profiles of bacon. Recombination and omission tests were performed using aroma compounds with a flavor dilution (FD) factor greater than 27; five volatiles were identified as key aroma compounds in non-smoked bacon, including hexanal, (E,E)-2,4-decadienal, 1-octen-3-ol, dihydro-5-pentyl-2(3H)-furanone, and 3-methyl-butanoic acid. Among these, hexanal and 1-octen-3-ol exhibited relatively high FD factors and odor activity values (OAVs), so they were confirmed as the primary contributors. Meanwhile, seven volatiles contributed to the unique aroma of non-smoked bacon in different regions. The difference in the aroma of bacon in different regions is mainly due to the content of various volatiles rather than the type. A comprehensive analysis of the aroma in non-smoked bacon can reveal theoretical information for improving the process and quality control of the product.

GC × GC-ToF-MS combined with multivariate statistical methods to explore the effects of L. paracasei fermentation on bread flavor characteristics

GC × GC-ToF-MS is increasingly used to analyze complex food flavors due to its high resolution and sensitivity, but few studies have used the method to identify aroma components of bread. For the first time, this study combines GC × GC-ToF-MS and multivariate statistical methods to explore the effects of L. paracasei fermentation on bread flavor characteristics. A total of 1534 volatile organic compounds were identified, of which 447 were obtained by metabolome normalization. Based on the variable importance for the projection and p values, 82 different compounds were screened in L. paracasei bread compared with yeast bread, and the total relative content was 1.52 times higher than that of yeast bread. 2-Furancarboxaldehyde, 5-methyl-, pentanoic acid, 2-hydroxy-4-methyl-, ethyl ester, pyrazine, 2,5-dimethyl- and γ-terpinene are aroma-presenting substances specific to L. paracasei bread that could be potential identification compounds. This study provides a new techno-theoretical approach for the characterization and discrimination of LAB bread flavors.

Optimization and validation of an HS-SPME/GC-MS method for determining volatile organic compounds in dry-cured ham

The formation of volatile organic compounds (VOCs) in dry-cured ham is a result of different biochemical and enzymatic processes. Moreover, accurately quantifying these VOCs is challenging since ham is a complex matrix, which contains compounds from various chemical families and a wide range of volatilities of different molecular masses. In this study, we systematically optimized and validated an analytical method for quantifying VOCs in dry-cured ham using headspace solid phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). Optimal SPME conditions were determined through both an experimental procedure (one-factor-at-a-time) and response surface methodology (RSM), revealing that a 60-min equilibration at 70°C, a 60-min extraction at the same temperature, and a 4-min desorption time at 250°C provided the most favorable results. To enhance quantitation, twelve multiple internal standards (ISTDs) were employed to address and improve the quantitation of the 12 VOCs. Method validation covered aspects of linearity, limits of detection (LOD: 0.03-1.13 mg kg-1), limits of quantitation (LOQ: 0.09-3.41 mg kg-1), and working ranges (0.01-19.1 mg kg-1). The practical application of this optimized method was demonstrated by analyzing dry-cured ham samples (n = 4), sourced from the Slovenian market. The initial statistical evaluation indicates that different types of dry-cured hams can be differentiated (with an 83.1% of accuracy) according to their aromatic profile. However, a larger sample size would be required to provide a more comprehensive assessment.

Study of Pansalt® or Laminaria Ochroleuca seaweed powder as potential NaCl replacers in dry-cured foal "cecina"

This study aimed to evaluate the effect of the total or partial replacement of NaCl by a commercial low-salt mixture Pansalt® (T1) or Kombu (L. ochroleuca) seaweed powder (T2), respectively, on the quality properties of dry-cured foal "cecina". Salt reformulation unaffected fat percentages, decreased (P < 0.001) moisture and ash contents, while protein amounts increased (P < 0.001) in the T2 batch. Considering the physicochemical variables, any significant differences were observed among batches, except for a*, water activity, and springiness values. T1 and T2 samples presented a significant (P < 0.001) sodium decrease of 39% and 48%, respectively, as well as, potassium and magnesium increase (P < 0.001). In addition, the seaweed improved (P < 0.001) calcium, iron, phosphorus, and zinc contents. All batches showed similar lipid profiles and the nutritional indices were in line with the health recommendations. NaCl replacement increased the proteolysis, causing the increment (P < 0.001) of the free amino acids total contents, especially in T2 samples. Changes were also detected in the aromatic profile of our samples, where lipid-derived compounds predominated in the CON batches, while substances originating from carbohydrate fermentation and amino acid breakdown were prevalent in reformulated samples, particularly in T2. In addition, the salting treatments did not affect the sensory profile, except for saltiness (T2). Hence, data indicated that the employ of these potential NaCl alternatives, in particular T2 formulation, represents a favorable approach to achieving equine "cecinas" with an enhanced mineral and healthier profile, without altering most of the sensorial properties.

Evaluation of Autochthonous Coagulase-Negative Staphylococci as Starter Cultures for the Production of Pastırma

The aim of the study was to investigate the effects of Staphylococcus xylosus 39, S. equorum 53, or S. vitulinus 75, previously isolated from pastırma, on the quality characteristics of pastırma, a Turkish dry-cured meat product, and to evaluate their potential use as starter cultures. The pastırma production was carried out with a traditional method. The control pastırma groups were manufactured without adding any starter culture. At the end of production, the groups were subjected to microbiological and physico-chemical analyses. The pH was above 5.5, and the aw value was below 0.90 in all groups. The strains used exhibited good adaptation to the pastırma. The S. equorum 53 decreased the thiobarbituric acid reactive substances (TBARS) value in pastırma, while the S. xylosus 39 increased the redness (a*) color value. The autochthonous strains caused a decrease in the palmitic acid (C16:0). However, they had no significant effect on the stearic acid (C18:0) and the oleic acid (C18:1n-9c). A total of 41 volatile compounds were identified in the groups. S. vitulinus 75 increased both benzaldehyde and 2-methyl-3-phenylpropanal levels. In addition, the principal component analysis (PCA) of volatile compounds provided a good separation, and PC1 separated S. xylosus 39 from other groups.

Comparing the aromatic profile of seven unheated edible insect species

Insects and insect-based products have gained increasing interest as human food because of their many technological, nutritional and environmental advantages, but they are still rejected by many Western consumers. Analytical knowledge of flavour compounds could contribute to enhancing product attractiveness to consumers. Therefore, the goal of this study was to examine the volatile compound profiles of 7 unheated insects: Zophobas morio (ZM), Tenebrio molitor (TM), Locusta migratoria (LM), Galleria mellonella (GM), Blaptica dubia (BD), Alphitobius diaperinus (ALD) and Acheta domesticus (ACD). A total of 67 compounds were identified. Carboxylic acids were predominant in ALD, BD, GM, TM and ZM, while ketones were the major family in ACD and linear hydrocarbons in LM. ZM contained the highest number of unpleasant odour compounds, including indole, also present in BD and GM, which is characterised by a low detection threshold.

Antibacterial and Antiproliferative Activities of Azadirachta indica Leaf Extract and Its Effect on Oil-in-Water Food Emulsion Stability

The present study aims to identify and quantify the phenolic compounds of Azadirachta indica leaf extract using HPLC-MS and to evaluate the antioxidant, antibacterial (against different Gram-positive and negative bacteria) and in vitro anti-proliferative activities of this extract (against breast, human liver and cervix adenocarcinoma-derived cells). The application of this extract as a natural antioxidant for food preservation was also tested on oil-in-water food emulsions for the first time in the present work in order to determine the use of Azadirachta indica leaves as a natural additive to preserve the food against lipid oxidation and rancidity. The results obtained revealed that 50%-aqueous ethanol leaf extract showed the best extraction yield (25.14%), which was characterized by a high content in phenolic compounds and strong antioxidant activity. Moreover, this leaf extract inhibited the growth of the bacterial strains tested (Staphylococcus aureus, Escherichia coli, Salmonella paratyphi and Micrococcus luteus) and showed better anti-proliferative activity against breast and cervix adenocarcinoma-derived cells than human liver cancer cells after 48 h of treatment. Additionally, Azadirachta indica leaf extract showed almost similar effects as gallic acid solutions (0.25% and 0.5%) in preserving the oxidation of oil-in-water food emulsions and prevented the formation of secondary oxidation products (malondialdehyde) as well. The results obtained suggested that extracts of Azadirachta indica leaves are a potential source of antioxidant and antibacterial compounds and pointed to the potential of these natural extracts as therapeutic agents.

Physicochemical properties of a new structural lipid from the enzymatical incorporation of flaxseed oil into mutton tallow

This study evaluated the physio-chemical properties of a structural lipid (SL) obtained by the enzymatical incorporation of flaxseed oil into mutton tallow (MT). By measuring the melting point, colour, safety, fatty acids, apparent viscosity, shear stress and volatile compounds of the samples, the results showed that compared to MT, SL exhibited lower L∗(lightness) value, melting point, apparent viscosity and shear stress (p < 0.05). Noteworthy, the Saturated fatty acids (SFA)content of MT was reduced from 61.46% to 25.49% (p < 0.05), although SL was found to be more prone to oxidation during storage. The clearest discrepancy in volatile compounds was the increase of heterocyclic compounds in SL. In summary, improving the edible properties of animal fats by adding vegetable oils is an effective solution, and SL may have a great potential to be developed into a high-quality product with improved nutritional composition of animal fat.

Studies on Flavor Compounds and Free Amino Acid Dynamic Characteristics of Fermented Pork Loin Ham with a Complex Starter

Staphylococcus simulans and Lactobacillus plantarum screened from Guizhou specialty food were used to prepare fermented pork loin ham. The sensory qualities and flavor profiles of fermented pork loin hams from 0 to 42 days were investigated in order to reveal the dynamics of fermented pork loin ham. The results show that total free amino acids (TFAA) content reached the highest value on the 35th day, and the umami amino acids, including aspartic acid (ASP), glutamic acid (GLU), glycine (GLY), and alanine (ALA), were the main amino acids in all periods. Notably, the RV coefficient (0.875) indicates that free amino acids (FAA) are highly correlated with the sensory score of the E-tongue. In terms of the volatile compounds identified, the esters content gradually increased between 7 and 42 days, and ethyl octanoate was the most abundant compound during all periods. These esters imparted a characteristic aroma component to the fermented pork loin ham. The most important finding was that the increase in the content of esters represented by octanoic acid-ethyl ester might be related to the increase in the content of FAA with the increase in fermentation time. Both the E-nose and E-tongue showed good discrimination ability for fermented tenderloin ham with different fermentation times, which was crucial in cases with large clusters. In addition, the multiple factor analysis (MFA) indicated that the E-nose aroma value might be the key factor in distinguishing fermented pork loin ham with different fermentation times.

Fatty Acid Composition and Volatile Profile of longissimus thoracis&nbsp;et&nbsp;lumborum Muscle from Burguete and Jaca Navarra Foals Fattened with Different Finishing Diets

The present study evaluated the effect of breed, Jaca Navarra (JN) vs. Burguete (BU), and finishing diet, conventional concentrate—diet 1 (D1) vs. silage and organic feed—diet 2 (D2), on the fatty acid composition and volatile profile of longissimus thoracis et lumborum muscle from forty-six foals. For this, foals were reared under a semi-extensive system and slaughtered at about 21 months of age. The outcomes showed that breed and finishing regime had a significant (p < 0.05) effect on the lipid and volatile profile of foal meat. In particular, JN foals reported higher polyunsaturated fatty acid contents and better nutritional indices in line with the health guidelines; whereas, BU and D1 groups generated higher amounts of total volatile compounds. However, it was the diet to occupy a central role in this study. Indeed, diet 2, due to its “ingredients” and composition, not only ameliorated the lipid profile of foal meat, but also reduced the generation of volatile compounds associated with lipid oxidation and minimized off-flavors. Thus, this diet could give an added value to the aromatic perception of meat and improve its sensorial acceptability.

Microwave-Assisted Extraction Coupled with Mass Spectrometry for Determining Five Volatile Compounds from Soy Sauces

As a popular fermented condiment in oriental countries, soy sauce plays a more and more important role in modern food culture due to its unique smell and delicious taste. With the help of microwave extraction and gas chromatography-tandem mass spectrometry, the sample preparation method is aimed to determine the content of cyclohexane, benzene, toluene, chlorobenzene, and styrene in soy sauce. The method was validated by examining the linearity, accuracy, specificity, precision, the limit of detection, and quantitation. Meanwhile, three key factors have an impact on the efficiency and accuracy of the method including extracting solvent, temperature, and time which were optimized. The result shows that the recoveries of spiked analytes ranged from 80.86% to 105.71%, the relative standard deviation of intraday and interday precision was no more than 12.1% and 12.5%, and the limit of detection and quantitation were 0.25-1.00 ng/mL and 0.50-2.00 ng/mL, respectively. The results also indicated that the proposed method was a simple, reliable, and sensitive approach for the determination trace amount of five harmful volatile organic compounds from soy sauce.

Effect of storage temperature on volatile marker compounds in cured loins fermented with Staphylococcus carnosus by brine injection

In this study, the influence of low (5 °C), intermediate (15 °C) and high (25 °C) storage temperatures on the profile of volatile compounds of North European cured loins fermented with Staphylococcus carnosus strains was investigated. In this context, proteolytic activity, bacterial growth, key volatile compounds and sensory attributes were studied. In conclusion, storage temperature significantly affected the volatile marker compounds. A multiple regression indicated significant effects of seven volatile compounds (acetophenone, benzaldehyde, butanone, 3-methylbutanal, 1-octen-3-ol, nonanal and pentanone) on the overall odor (R2 = 95.9%) and overall flavor (R2 = 81.1%). The sum of the marker volatiles aldehydes, ketones and alcohol increased with rising temperatures and the highest amounts of the odor active 3-methylbutanal up to 155 and 166 ng/g meat were detected in high temperature-stored loins. Moreover, the addition of S. carnosus strain LTH 3838 showed maximum effect at 5 °C-storage temperature in comparison to the control.

Effect of Neem (Azadirachta indica L.) on Lipid Oxidation in Raw Chilled Beef Patties

The aim of this study was to determine the total polyphenol content, radical scavenging and antimicrobial activities of Azadirachta indica (A. indica) and to evaluate their effect on shelf-life stability of raw beef patties during refrigerated storage at 4 ± 1 °C. During 11 days of storage, the antioxidant effect of A. indica on ground beef meat was investigated by the determination of lipid oxidation, pH, anti-radical activity, color, hexanal content, and microbial growth. The results obtained showed that fresh A. indica leaves and synthetic conservative behaved in the same way and retarded the lipid oxidation of chilled beef patties while increasing their pH (5.40 and 5.45, respectively). It can also be said that A. indica limited the loss of color, reduced the metmyoglobin formation (36.70%) and had a significant effect on bacterial growth and hexanal content. In addition, the results obtained through anti-radical and antimicrobial properties showed proportional values of total polyphenol content and radical scavenging activity of leaf extracts as they showed their antimicrobial effect against some bacteria such as Staphylococcus aureus and Micrococcus luteus, among others. These results support the involvement of A. indica in the food industry as a natural antioxidant that could replace synthetic ones.

Volatile profile of fermented sausages with commercial probiotic strains and fructooligosaccharides

The effect of the partial substitution of pork back fat by fructooligosaccharides (FOS) and the probiotic strains Lactobacillus paracasei and Lactobacillus rhmanosus on the generation of volatile organic compounds in fermented sausages was investigated. The results obtained showed that these factors significantly affected the total content of organic volatile compounds (7484, 8114, 8372 and 10,737 AU × 10⁴/g for FOS.GG, CON, FOS.BGP1 and FOS samples, respectively). A total of 59 volatile components, mainly hydrocarbons, ketones and esters were isolated. The reduction of fat content by including FOS in the formulation results in positive effects and a greater stability of the volatile profile of the fermented sausages, increasing ester compounds and reducing the undesirable notes of hexanal (probiotic samples showed values < 2 AU × 10⁴/g). Moreover, there was a symbiotic effect when the aforementioned prebiotic fiber was combined with probiotic Lactobacillus strains.

Analysis of volatile profiles of green Hawai'ian coffee beans damaged by the coffee berry borer (Hypothenemus hampei)

BACKGROUND

The coffee berry borer (CBB), Hypothenemus hampei, is the most destructive insect pest of coffee globally, causing significant losses in yield and leading to 'off' flavors in damaged beans. Automated headspace sampling (AHS) and gas chromatography-mass spectrometry (GC-MS) were used to investigate changes in the volatile profiles of CBB-damaged green coffee beans. Green coffee from three coffee farms on the island of Hawai'i were sorted into three levels of CBB damage: non-damaged, slightly damaged (1-2 pinholes/bean), and heavily damaged (> 2 pinholes/bean).

RESULTS

Distinct differences were found between green coffee bean samples based on the amounts of eight prominent volatiles. The amount of CBB damage was particularly correlated with the amount of both hexanal and 2-pentylfuran. Principal component analysis showed clustering of non-damaged green beans, which did not overlap with the slightly or heavily damaged clusters. Good separation was also found between a mixture of 50% slightly damaged and non-damaged coffee. However, 20% slightly damaged and non-damaged coffee clusters showed strong overlap.

CONCLUSION

Understanding the effects of CBB damage on coffee flavor profiles is critical to quality control for this valuable agricultural product. The results of this study show that the volatile profiles of green coffee beans vary with CBB damage. With specific volatile profiles for CBB-damaged coffee identified, coffee samples can be tested in the lab, or potentially on the farm or in coffee mills, to identify high levels of CBB damage that may lead to off flavors and a reduction in product quality and value. © 2018 Society of Chemical Industry.

Volatile changes in Hawaiian noni fruit, Morinda citrifolia L., during ripening and fermentation

BACKGROUND

Noni fruit (Morinda citrifolia L., Rubiaceae) has been used in traditional medicine throughout the tropics and subtropics and is now attracting interest in western medicine. Fermented noni juice is of particular interest for its promising antitumor activity. The present study collected and analyzed volatiles released at nine time intervals by noni fruit during ripening and fermentation using headspace autosampling coupled to gas chromatography-mass spectrometry.

RESULTS

Twenty-three noni volatiles were identified and relatively quantified. In addition to volatiles previously identified in noni, four novel volatile 3-methyl-2/3-butenyl esters were identified via the synthesis of reference compounds. Principle component analysis (PCA) and canonical discriminant analysis (CDA) were used to facilitate multidimensional pattern recognition. PCA showed that ripening noni fruit cluster into three groups, pre-ripe, fully ripe (translucent) and fermented, based on released volatiles. CDA could 83.8% correctly classify noni samples when all ripeness stages were analyzed and 100% when samples were classified into the three PCA groupings.

CONCLUSION

The results of the present study confirm the identities of 3-methyl-2/3-butenyl esters, both novel and previously identified, through the synthesis of reference compounds. These esters constitute a large percentage of the volatiles released by fully ripe and fermented noni and likely produced from the decomposition of noniosides, a group of unique glucosides present in the fruit. © 2017 Society of Chemical Industry.

Kinetics of volatile marker compounds during ripening of cured loins inoculated with Staphylococcus carnosus

BACKGROUND

The current study was designed to investigate the influence of ripening time (12 weeks, 15 °C) on the volatile compounds and sensory acceptance for North European cured loins inoculated with a proteolytic Staphylococcus carnosus starter culture.

RESULTS

The results demonstrated that the trend of volatile compounds, sensory acceptance and proteolytic activity increased during a ripening of 7 to 9 weeks. A further ripening led to a plateau phase for sensory attributes and aroma-relevant volatile compounds such as benzaldehyde, nonanone and acetophenone. The inoculation of the proteolytic S. carnosus LTH 3838 significantly increased aroma-relevant volatile compounds (3-methylbutanal, benzaldehyde, acetophenone, 1-octen-3-ol) and sensory acceptance up to a score 3.5 and 3.6 for the overall odour and taste by week 9. In addition, compounds such as nonanal, hexanal, 2-pentanone and nonanone, which originate from lipid oxidation, were significantly limited by S. carnosus LTH 3838.

CONCLUSION

A ripening time of 7 to 9 weeks seems to be an optimal period for the production of aroma intensive smoked North European cured loins. © 2016 Society of Chemical Industry.