Volatile Compounds of Raw Beef from 5 Local Spanish Cattle Breeds Stored Under Modified Atmosphere

Towards Reducing Food Wastage: Analysis of Degradation Products Formed during Meat Spoilage under Different Conditions

Foodstuffs, particularly perishable ones such as meat, are frequently discarded once the best-before date has been reached, despite the possibility of their continued suitability for human consumption. The implementation of intelligent packaging has the potential to contribute to a reduction in food wastage by enabling the monitoring of meat freshness during storage time independently of the best-before date. The process of meat spoilage is associated with the formation of specific degradation products, some of which can be potentially utilized as spoilage indicators in intelligent packaging. The aim of the review is to identify degradation products whose concentration correlates with meat shelf life and to evaluate their potential use as spoilage indicators in intelligent packaging. To this end, a comprehensive literature research was conducted to identify the factors influencing meat spoilage and the eight key degradation products (carboxylic acids, biogenic amines, total volatile basic nitrogen, aldehydes, alcohols, ketones, sulfur compounds, and esters) associated with this process. These degradation products were analyzed for their correlation with meat shelf life at different temperatures, atmospheres, and meat types and for their applicability in intelligent packaging. The review provides an overview of these degradation products, comparing their potential to indicate spoilage across different meat types and storage conditions. The findings suggest that while no single degradation product universally indicates spoilage across all meat types and conditions, compounds like carboxylic acids, biogenic amines, and volatile basic nitrogen warrant further investigation. The review elucidates the intricacies inherent in identifying a singular spoilage indicator but underscores the potential of combining specific degradation products to expand the scope of applications in intelligent packaging. Further research (e.g., storage tests in which the concentrations of these substances are specifically examined or research on which indicator substance responds to these degradation products) is recommended to explore these combinations with a view to broadening their applicability.

Contribution of mono- and co-culture of Pseudomonas paralactis, Acinetobacter MN21 and Stenotrophomonas maltophilia to the spoilage of chill-stored lamb

Exploring the contribution of common microorganisms to spoilage is of great significance in inhibiting spoilage in lamb. This work investigated the extent of protein degradation and profile changes of free amino acids (FAAs), free fatty acids (FFAs) and volatile organic compounds (VOCs) in lamb caused by single- and co-culture of the common aerobic spoilage bacteria, P. paralactis, Ac. MN21 and S. maltophilia. Meanwhile, some key VOCs produced by the three bacteria during lamb spoilage were also screened by orthogonal partial least square discriminant analysis and difference value in VOCs content between inoculated groups and sterile group. Lamb inoculated with P. paralactis had the higher total viable counts, pH, total volatile base nitrogen and TCA-soluble peptides than those with the other two bacteria. Some FAAs and FFAs could be uniquely degraded by P. paralactis but not Ac. MN21 and S. maltophilia, such as Arg, Glu, C15:0, C18:0 and C18:1n9t. Co-culture of the three bacteria significantly promoted the overall spoilage, including bacterial growth, proteolysis and lipolysis. Key VOCs produced by P. paralactis were 2, 3-octanedione, those by Ac. MN21 were 1-octanol, octanal, hexanoic acid, 1-pentanol and hexanoic acid methyl ester, and that by S. maltophilia were hexanoic acid. The production of extensive key-VOCs was significantly and negatively correlated with C20:0, C23:0 and C18:ln9t degradation. This study can provide a basis for inhibiting common spoilage bacteria and promoting high-quality processing of fresh lamb.

The Effect of Kosher Determinants of Beef on Its Color, Texture Profile and Sensory Evaluation

Traditional ritual slaughter is an underlying practice in religious Jewish communities and it translates into eating in accordance with core beliefs. This paper aims to comprehensively analyze factors determining the kosher status of beef (sex, slaughter method, and muscle type) and assess their impact on selected quality properties, such as color or texture profile. Sensory evaluation was also performed. The muscles were obtained from 80 carcasses (50% of heifers and 50% of young bulls). The experimental results indicate that each studied kosherness determinant influenced beef quality properties. The process of koshering caused the darkening of beef and lowered the share of color parameters red (a*) and yellow (b*). The influence of the type of slaughter on the values of adhesiveness, gumminess, and chewiness of beef was confirmed; higher values were mostly obtained in the muscles of cattle from kosher slaughter. As to sensory evaluation, the study showed that in the case of muscle type, the sex and slaughter method positively influenced only some of the properties.

Influence of Lactobacillus helveticus ZF22 and TR1-1-3 strains on the aromatic flavor of fermented sausages

In this study, five strains isolated from traditional Inner Mongolian air-dried meat products were used, two Lactobacillus helveticus strains, ZF22 and TR1-1-3, with potent antibacterial activity, acid, salt, and nitrite tolerance, were selected for this study. Lactic acid bacteria (LAB) (Lactobacillus helveticus ZF22 and TR1-1-3) were inoculated into fermented sausages at 10⁷ CFU/g and their volatiles were studied during fermentation and storage. Clustering heat map and principal component analysis (PCA) were used to identify differentiating flavor components in uninoculated and inoculated sausages. The results showed that 72 volatile flavor substances were identified during the fermentation of the fermented sausages and that inoculation with Lactobacillus helveticus ZF22 and TR1-1-3 increased the proportion of acids, ketones and alkanes. Moreover, the clustering heat map demonstrated that esters such as ethyl isobutyrate, ethyl acetate, and ethyl valerate were more abundant in TR1-1-3 and ZF22 than ZR. The PCA analysis showed that the volatile compounds of the three fermented sausages were distributed in separate quadrants, suggesting that the volatile compound compositions of the three fermented sausages differed significantly. Our findings suggest that inoculating fermented sausages with Lactobacillus helveticus TR1-1-3 and ZF22 can improve flavor by enhancing the type and amount of flavor compounds.

Formation and Analysis of Volatile and Odor Compounds in Meat-A Review

The volatile composition and odor of meat and meat products is based on the precursors present in the raw meat. These are influenced by various pre-slaughter factors (species, breed, sex, age, feed, muscle type). Furthermore, post-mortem conditions (chiller aging, cooking conditions, curing, fermentation, etc.) determine the development of meat volatile organic compounds (VOCs). In this review, the main reactions leading to the development of meat VOCs such as the Maillard reaction; Strecker degradation; lipid oxidation; and thiamine, carbohydrate, and nucleotide degradation are described. The important pre-slaughter factors and post-mortem conditions influencing meat VOCs are discussed. Finally, the pros, cons, and future perspectives of the most commonly used sample preparation techniques (solid-phase microextraction, stir bar sorptive extraction, dynamic headspace extraction) and analytical methods (gas chromatography mass spectrometry and olfactometry, as well as electronic noses) for the analysis of meat VOCs are discussed, and the continued importance of sensorial analysis is pinpointed.

Improving the Aromatic Profile of Plant-Based Meat Alternatives: Effect of Myoglobin Addition on Volatiles

Market demand for palatable plant-based meat alternatives is on the rise. One of the challenges is formulating products with sensorial characteristics similar to conventional meat. In this study, the effect of myoglobin on the aromatic profile of plant-based meat alternatives was assessed. Plant-based burgers were made with soy-textured protein, supplemented with three levels of myoglobin (0, 0.5 and 1.0%, the latter two mimicking endogenous myoglobin levels in meat), and grilled for 12 min at 250 °C. To evaluate the aromatic profile of the compounds, raw and grilled samples were subjected to headspace solid-phase microextraction (HS-SPME) followed by gas chromatography-mass spectrometry (GC-MS). Principal component analysis (PCA) analysis was then performed to visualize the interaction between grilling and myoglobin addition, and the effect exerted on the resulting aromatic profile. Myoglobin significantly affected several classes of volatile compounds, either by itself or in conjunction with grilling. A notable increase in aldehydes and a decrease in hydrocarbons were noted after adding myoglobin. As expected, an increase in pyrazines was observed after grilling. The results suggest myoglobin positively influences the aromatic profile of plant-based meat alternatives, contributing to a profile closer to the one of conventional meat.

Fatty Acid Composition and Volatile Profile of longissimus thoracis et 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.

Effect of ageing time on the volatile compounds from cooked horse meat

Volatile compounds from cooked and aged (0, 7, 14, 21 days) Hispano-Bretón horse meat (loin) were analyzed by solid-phase microextraction coupled to gas chromatography-mass spectrometry. A total of 77 volatile compounds were found, from which aldehydes were the predominant family. Most of the identified compounds had their origin in the degradation of lipids, with a negligible contribution of Maillard derived products. Odour impact ratios were calculated and used as indicators of the contribution of each compound to the total aroma and aldehydes were, in general, the major contributors to cooked horse meat aroma. Results revealed that ageing affected 15 of the volatile compounds detected. From them, hexadecanal and 2- and 3-methylbutanal significantly increased during ageing, presumably affecting the cooked meat odour as these have considerable odorant impact. Under the present study conditions, periods longer than 14 days would be necessary for significant changes in the volatile profile of cooked horse meat.

Odor Emissions from Raw Meat of Freshly Slaughtered Cattle during Inspection

Raw meat of Freshly Slaughtered Cattle (FSC) is characterized by a very weak odor defined as slightly sweet, which could interfere in off-odor assessment during post-mortem inspection by an official veterinarian. Despite this, no information is reported in the literature on the volatiles which are emitted by FSC meat. Thus, this research aimed to study the volatile profile of raw cattle meat at different times within 24 h of slaughtering. Volatiles were analyzed and quantified using HS-SPME-GC-MS. γ-Butyrolactone, acetoin, and to a lesser extent, acid acetic were found to be the odor-active compounds of raw meat from freshly slaughtered cattle. Quantitative differences were observed up to 24 h; since the lowest levels of the odor-active compounds were reached between two and three hours from slaughtering, this period could be the most suitable for the post-mortem inspection process.

Detection of Volatiles from Raw Beef Meat from Different Packaging Systems Using Solid-Phase Microextraction GC-Accurate Mass Spectrometry

The volatile profile of raw beef contains vital information related to meat quality and freshness. This qualitative study examines the effect of packaging system on the formation and release of volatile organic compounds (VOCs) from raw beef over time, relative to the packaging best before date (BBD). The three packaging systems investigated were modified atmospheric packaging, vacuum packaging, and cling-wrapped packaging. Porterhouse steak samples with the same BBD were analysed from 3 days before to 3 days after the BBD. VOCs were detected via preconcentration using solid-phase microextraction combined with gas chromatography–accurate mass quadrupole time-of-flight mass spectrometry. In total, 35 different VOCs were tentatively identified. Interestingly, there was no clear relationship of the VOCs detected between the three packaging systems, with only carbon disulphide and acetoin, both known volatiles of beef, detected in all three. This is the first study to investigate the effects of commercial packaging systems on VOC formation; it provides an understanding of the relationship of VOCs to the BBD that is essential for the development of on-pack freshness and quality sensors.

Influence of the Production System (Intensive vs. Extensive) at Farm Level on Proximate Composition and Volatile Compounds of Portuguese Lamb Meat

Today’s society demands healthy meat with a special emphasis on integrated animal husbandry combined with the concern for animal welfare. In this sense, the raising of lambs in an extensive system has been one of the most common practices, which results in meats with high nutritional value. However, both the production system and the diet play a fundamental role in the chemical composition of the meat, which has a direct impact on the content of volatile compounds. Thus, the aim of this study was to determine the effect of two production systems (intensive and extensive) on the chemical composition and volatile profile of lamb meat. Twenty-eight lambs of the Bordaleira-de-Entre-Douro-e-Minho (BEDM) sheep breed were raised for meat production under the intensive or extensive system and were fed with concentrate and pasture, respectively. All animals were carried out in the muscle longissimus thoracis et lumborum. Results evidenced that all the composition parameters were affected by the production system. Extensively-reared lambs produced meat with the highest fat and protein contents, while these animals had the lowest percentages of moisture and ash. Similarly, the total content of volatile compounds was affected (p < 0.05) by the production system and were higher in the meat of lambs reared extensively. Furthermore, the content of total acids, alcohols, aldehydes, esters, ethers, furans and sulfur compounds as well as most of the individual compounds were also affected (p < 0.05) by the production system, whereas total hydrocarbons and ketones were not affected (p > 0.05). As a general conclusion, the production system had very high influence not only in proximate composition but also in the volatile compounds.

Volatile Compounds, Odour and Flavour Attributes of Lamb Meat from the Navarra Breed as Affected by Ageing

This study aimed to assess the influence of ageing on the volatile compounds, as well as odour and flavour attributes of lamb meat from the Navarra breed. Twenty-one male lambs were fed a commercial concentrate diet after weaning and were harvested at 101 ± 6.5 days of age. From the Longissimus thoracis, 26 volatile compounds were identified, with hexanal, 2-propanone, and nonanal the most abundant (57.17% relative percentage abundance, RPA). The effect of ageing (1 vs. 4 d) was observed (p < 0.05) in six compounds: 1,4-dimethylbenzene decreased with ageing, while tridecane, 3-methylbutanal, 2-heptanone, 3-octanone, and 1-octen-3-ol increased. In general, ageing was linked to a decrease in livery and bloody flavour, bloody odour and ethanal, and an increase in pentane, hexanal, and heptanal, which are usually associated with fresh green grass and fat descriptors. Consequently, ageing lamb from the Navarra breed for four days might have a positive effect on meat sensory odour and flavour quality.

Composition of Volatile Compounds in Heat-Treated Meat from Polish Native Sheep Breeds Using HS-SPME-GC/MS – Chemometric Classification Based on Breed and Age

In order to characterize the volatile compounds composition of lamb meat, 3 groups of baked leg muscle samples from two Polish native sheep breeds: Świniarka aged 9 months (S9), Wrzosówka aged 9 months (W9), and Wrzosówka aged 7 months (W7), were analyzed by HS-SPME-GC/MS, followed by multivariate statistics comprising the F-ratio method for variables pre-selection, and PCA-LDA analysis. Ninety seven volatile compounds were determined, out of which 74 were identified. The largest classes of volatile compounds were aldehydes and furans followed by alcohols, hydrocarbons, ketones, and sulfur and nitrogen compounds. Statistically significant differences between the S9, W9, and W7 groups were observed for 11 volatiles, i.e.: pentanal; hexanal; 1,3-octadiene; benzaldehyde; 3-ethyl-2-methyl-1,3-hexadiene; 3-octen-2-one; 2-octenal; 2-hexylfuran; tetradecanal; pentadecanal; hexadecanal. The HS-SPME-GC/MS method coupled with chemometrics, based on the relative intensity spectral data of these volatiles, proved to be an effective tool for the discrimination of lambs according to breed and age. The classification accuracy value for the S9, W9, and W7 groups was 100%.

Effects of microbial fermentation on the flavor of cured duck legs

In this study, fermentation with Lactobacillus plantarum and Saccharomyces cerevisiae was applied to improve the flavor of cured duck leg meat. Odor and taste evaluations, lipid oxidation, volatile flavor substances, and protein degradation were determined to investigate the effects of microbial fermentation on flavor improvement. The results showed that the utilization of L. plantarum represented the most significant effect on lipid peroxidation inhibition (the lowest value of thiobarbituric acid reactive substances and the highest content of polyunsaturated fatty acids) and also enhanced the generation of volatile flavor substances than nonfermented duck meat. Microbial fermentation accelerated protein degradation in duck meat. S. cerevisiae could produce glutamate to promote the umami taste flavor of cured duck leg meat, and L. plantarum significantly improved the sweet taste by releasing alanine. Meanwhile, mixed fermentation with the two microbial species resulted in the combination of both of their advantages. These findings not only indicate the potential application of microbial fermentation in characteristic duck meat but also indicate that fermentation improves sensory properties of duck products significantly.

Spoilage Potential of Pseudomonas (P. fragi, P. putida) and LAB (Leuconostoc mesenteroides, Lactobacillus sakei) Strains and Their Volatilome Profile During Storage of Sterile Pork Meat Using GC/MS and Data Analytics

The aim of the present study was to investigate the evolution of the volatile compounds of aerobically stored sterile pork meat as a consequence of the metabolic activities of inoculated specific spoilage microorganisms. Thus, Pseudomonas fragi, Pseudomonas putida, Lactobacillus sakei and Leuconostoc mesenteroides were inoculated in monocultures, dual cultures and a cocktail culture of all strains on sterile pork meat stored aerobically at 4 and 10 °C. Microbiological and sensory analyses, as well as pH measurements, were performed, along with headspace solid-phase microextraction gas chromatography/mass spectroscopy (headspace SPME-GC/MS) analysis. Data analytics were used to correlate the volatile compounds with the spoilage potential of each stain using multivariate data analysis. The results for the sensory discrimination showed that the volatiles that dominated in spoiled samples consisted mostly of alcohols, ketones and two esters (butyl acetate and ethyl acetate), while at fresh samples, dimethyl sulfide, furans, acetoin and ethyl lactate were detected. On the other hand, 2-butanone, diacetyl and acetaldehyde were among the volatile compounds that were mainly correlated with the inoculated meat during storage. In addition, P. fragi was positively correlated with a higher number of volatiles compared to the other strains, strengthening the hypothesis that volatile compound production is strain-dependent.

Characterization of the Volatiles and Quality of Hybrid Grouper and Their Relationship to Changes of Microbial Community During Storage at 4 °C

To investigate the effects of spoilage bacteria on aquatic product quality and volatile organic compounds (VOCs) in hybrid grouper (Epinephelus fuscoguttatus ♀×Epinephelus lanceolatus ♂), the physical conditions were evaluated, the chemical changes including color, total volatile base nitrogen (TVB-N), VOCs, and free amino acids (FFAs) were determined, and biological profiles were made through microbial community (total viable counts (TVC), 16S rRNA gene amplification sequencing, and next-generation sequencing (NGS) technology on hybrid grouper, which were stored at 4 °C for 10 days. The results showed that the whiteness and TVB-N of grouper increased throughout the storage period. The contents of glycine, alanine, and total free amino acid decreased with the microbial activity towards the end of the study period. At the end of storage, the TVC reached 9.0 log10 (CFU/g). Seventy eight strains of bacteria were isolated from the hybrid grouper, most of which were shown to be Pseudomonas spp., after 16S rRNA sequencing. The results of the NGS test showed that the diversity of dominant bacteria decreased with time; Pseudomonas azotoformans was the dominant spoilage bacteria at the end of storage. The VOCs of fish and bacteria in the grouper's spoilage process were presented in headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS). Twenty eight compounds were identified in hybrid grouper, among which alcohol and aldehyde were used to characterize freshness, both of which were not only related to the overall flavor of the grouper, but were also affected by microbial activity. However, due to the complexity of microbial communities in aquatic products, the correlation between community changes and VOCs needs further research. This study provides insights into the correlation between VOCs and specific spoilage organisms (SSOs) through the analysis of the microbial community and VOCs.

Carbon Chain Length of Lipid Oxidation Products Influence Lactate Dehydrogenase and NADH-Dependent Metmyoglobin Reductase Activity

The biochemical basis of lower metmyoglobin reducing activity (MRA) in high-oxygen modified atmospheric packaged (HiOx-MAP) beef than those in vacuum and polyvinyl chloride (PVC) packaging is not clear. To explore this, the effects of lipid oxidation products with varying carbon chain length on lactate dehydrogenase (LDH) and NADH-dependent metmyoglobin reductase activity were evaluated. Surface color, MRA, and lipid oxidation of beef longissimus lumborum steaks (n = 10) were measured during 6-day display. Further, two enzymes, LDH and NADH-dependent metmyoglobin reductase (n = 5), critical for MRA were incubated with or without (control) lipid oxidation products of varying carbon chain length: malondialdehyde (3-carbon), hexenal (6-carbon), and 4-hydroxynonenal (9-carbon). Steaks in HiOx-MAP had greater (P < 0.05) redness than vacuum and PVC, but had lower (P < 0.05) MRA and greater (P < 0.05) lipid oxidation on day 6. LDH and NADH-dependent metmyoglobin reductase activities were differentially influenced by lipid oxidation products (P < 0.05). The results indicate that the difference in reactivity of various lipid oxidation products on LDH (HNE > MDA = hexenal) and NADH-dependent metmyoglobin reductase (HNE = MDA > hexenal) activity could be responsible for lower MRA in HiOx-MAP.

Effects of freezing and thawing on microbiological and physical-chemical properties of dry-aged beef

This study evaluated the effects of freezing, prior to and after dry aging, on the microbiological and physical-chemical quality of beef. Strip loins (n = 24) from 12 carcasses were assigned to four treatments: non-frozen dry aging (Dry); dry aging, steak fabrication, freezing and slow thawing (Dry + ST); freezing, fast thawing (FT; 20 °C/15 h) and dry aging (FT + Dry); freezing, slow thawing (ST; 4 °C/48 h) and dry aging (ST + Dry). Freezing conditions were - 20 °C/28 days and dry aging conditions were 2 °C/70% relative humidity, for 28 days. Freezing prior to dry aging did not affect the microbial counts compared to Dry. However, FT + Dry and ST + Dry increased (16%) total process loss (P < .05) compared to Dry and Dry+ST. Moreover, freezing changed volatile compounds profile. Thus, freezing prior to dry aging was not a feasible process due to increased process loss, while freezing after dry aging was considered a viable alternative to preserve the steaks without compromising beef physical-chemical traits.

Volatile flavor compounds vary by beef product type and degree of doneness

This study aimed to determine how quality grade and degree of doneness (DOD) influence the development of volatile compounds among beef whole muscle and ground patties. Volatile compounds were quantified via head space solid phase microextraction from samples tempered in refrigerated temperatures (3 to 5 °C), room temperature (24 to 26 °C), or cooked on an electric clamshell-style grill to an endpoint temperature of 55, 60, 71, or 77 °C. Collected samples were subsequently determined by gas chromatography mass spectrometry. Prominent compounds known to be the result of the Maillard reaction or lipid degradation were retained for comparison. Four Strecker aldehydes, 4 pyrazines, and one ester had a 3-way interaction between quality grade, DOD, and product type (each P < 0.001). Pyrazine concentrations did not differ (P > 0.05) in ground patties and was comparably greater (P < 0.05) in steaks; in Prime and Low Choice steaks, pyrazine concentration increased (P < 0.05) as DOD increased. A 2-way interaction between quality grade and product type was observed for acetaldehyde, dimethyl disulfide, 1-penten-3-ol, butanoic acid, hexanal, octanal, nonanal, and 2-heptanone. Among which, octanal and nonanal were greater (P < 0.05) in Prime steaks compared with ground patties. Another 2-way interaction, quality grade and DOD, was observed in 2 ketones, an alcohol, 2 esters, and 2 aldehydes. For example, 2,3-butanedione was greater (P < 0.05) in concentration in Prime 4 °C samples compared with Low Choice and Standard. The final 2-way interaction of DOD and product type was observed in 3 ketones, 2 sulfur compounds, 2 esters, 5 aldehydes, 2 carboxylic acids, and a ketone. For example, 2-heptanone was greater (P < 0.05) in concentration in ground patties compared to steaks in all degrees of doneness except 4 °C. Overall, these results indicate that the volatile flavor profile of beef is greatly influenced by product type and DOD. Generally, consumers select beef based on product type and determine their cookery approach. Therefore, consumers may greatly influence final beef flavor profile.

Volatile Profile of Raw Lamb Meat Stored at 4 ± 1 °C: The Potential of Specific Aldehyde Ratios as Indicators of Lamb Meat Quality

The objectives of the present study were: (a) to evaluate the aroma evolution of raw lamb packaged in multi-layer coating film and stored at 4 ± 1 °C, with respect to storage time and (b) to investigate whether specific aldehyde ratios could serve as markers of lamb meat freshness and degree of oxidation. Volatile compounds were determined using headspace solid phase microextraction coupled to gas chromatography/mass spectrometry. Results showed that the most dominant volatiles were 2,2,4,6,6-pentamethyl-heptane, hexanal, 1-octen-3-ol, 1-hexanol, carbon disulfide and p-cymene. Volatile compound content was increased during storage time. However, statistically significant differences were recorded only for hexanal, heptanal, and nonanal (p < 0.05). Additionally, the evolution of aldehydes during storage recorded a positive Pearson’s correlation (r) (p < 0.05), whereas hexanal to nonanal, heptanal to nonanal, octanal to nonanal ratios, along with the sum of aldehydes to nonanal ratio, were positively correlated (r = 0.83–1.00) with the degree of oxidation (mg malonic dialdehyde per kg of lamb meat). A perfect Pearson’s correlation (r = 1) was obtained for the ratio hexanal to nonanal. Therefore, this ratio is proposed as an indicator of lamb meat freshness and overall quality.

Ageing and retail display time in raw beef odour according to the degree of lipid oxidation

This study aims to assess the changes in beef aroma over time when steaks from pre-aged knuckles are stored in retail display under high oxygen conditions for 15 or 22days in vacuum conditions. Odorous volatile compounds were analysed by solid-phase microextraction/gas chromatography-mass spectrometry. Results were grouped as low, medium and high oxidative groups according to thiobarbituric acid reactive substances values after 9days of display. The intensity of off-odours in the raw meat increased with ageing and display time and oxidative groups. Based on correlations between the variables and regressions of the compounds through display, eight compounds were proposed as odour shelf-life markers. Among them, five were most sensitive and precise in all oxidative groups: 1-hexanol in meat aged for 15days, ethyl- octanoate and 2-pentylfuran in meat aged for 22days, and pentanoic and hexanoic acids in the two studied ageing times.

Implementation of multivariate techniques for the selection of volatile compounds as indicators of sensory quality of raw beef

This study was performed in order to select volatile compounds to predict the off-odour and overall assessment of raw beef's freshness Maronesa breed, using multivariate analysis. M. longissimus dorsi packed in vacuum and MAP (70 % O2/20 % CO2/10 % N2) stored at 4 ºC were examined for off-odour perception as well as the overall assessment of freshness at 10 and 21 days post mortem. The results achieved in this study demonstrated that the selected volatile compounds could be considered as volatile indicators of beef spoilage, enclosing information for discrimination of Maronesa beef samples in sensory classes of odour corresponding to unspoiled and spoiled levels. Fifty-four volatile compounds were detected. A significant increase of aldehydes, ketones and alcohols were observed during storage in MAP. 2 and 3-methylbutanal, 2 and 3-methylbutanol, 1-pentanol, 1-hexanol, 2,3-octanedione, 3,5-octanedione, octanal and nonanal were suggested as indicators of beef spoilage. 3-methylpentane was considered as a marker in the first stages of spoilage in beef, decreasing during storage. Data were examined using PCR and PLSR models for different optimal subsets of volatile compounds. The simplicity and usefulness of the technique in using 0/1 data in preserving high levels of accuracy was also prevalent. The powerful analytical methodologies for reducing variables and the choice of optimal subsets could be advantageous in both basic research and the routine quality control of chilled beef.

Natural neo acids and neo alkanes: their analogs and derivatives

This review presents more than 260 naturally occurring (as well as 47 synthesized) neo fatty (carboxylic) acids, neo alkanes, and their analogs and derivatives, isolated and identified from plants, algae, fungi, marine invertebrates, and microorganisms, that demonstrate different biological activities. These natural metabolites are good prospects for future chemical preparations as antioxidants, and also as anticancer, antimicrobial, and antibacterial agents. Described also are some synthetic bioactive compounds containing a tertiary butyl group(s) that have shown high anticancer, antifungal, and other activities. Applications of some neo fatty (carboxylic) acid derivatives in cosmetic, agronomic, and pharmaceutical industries also are considered. This is the first review to consider naturally occurring neo fatty (carboxylic) acids, neo alkanes, and other metabolites containing a tertiary butyl group(s) [or tert-butyl unit(s)].