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.

During the aging process, cells can enter cellular senescence, a state in which cells leave the cell cycle but remain viable. This mechanism is thought to protect tissues from propagation of damaged cells and the number of senescent cells has been shown to increase with age. The speed of aging determines the lifespan of a species and it varies significantly in different species. To assess the progress of cellular senescence during lifetime, we performed a comparative longitudinal study using histochemical detection of the senescence-associated beta-galactosidase as senescence marker to map the staining patterns in organs of the long-lived zebrafish and the short-lived turquoise killifish using light- and electron microscopy. We compared age stages corresponding to human stages of newborn, childhood, adolescence, adult and old age. We found tissue-specific but conserved signal patterns with respect to organ distribution. However, we found dramatic differences in the onset of tissue staining. The stained zebrafish organs show little to no signal at newborn age followed by a gradual increase in signal intensity, whereas the organs of the short-lived killifish show an early onset of staining already at newborn stage, which remains conspicuous at all age stages. The most prominent signal was found in liver, intestine, kidney and heart, with the latter showing the most prominent interspecies divergence in onset of staining and in staining intensity. In addition, we found staining predominantly in epithelial cells, some of which are post-mitotic, such as the intestinal epithelial lining. We hypothesize that the association of the strong and early-onset signal pattern in the short-lived killifish is consistent with a protective mechanism in a fast growing species. Furthermore, we believe that staining in post-mitotic cells may play a role in maintaining tissue integrity, suggesting different roles for cellular senescence during life.

The process of aging is associated with a decline in cell, tissue, and organ function, leading to a range of health problems. Increasing evidence indicates that dietary restriction can counteract age‐dependent effects and improve health and longevity in whole organisms, but less is known about the influence of aging and the impact of nutrition on individual organs of an organism. In this study, we examined the intestine of the very short‐lived aging model system, the African turquoise killifish ( Nothobranchius furzeri ), throughout its lifetime. We investigated the effects of age and nutrition on the preservation of gut tissue at stages corresponding to human neonatal, adolescent, adult, and old age, and integrated morphological measurements, histology, and transcriptomics. The intestinal mucosa is characterized by folds and intervening interfold regions, where intestinal stem cells localize. The stem cells occur in clusters, and the cycle time of stem cells increases with age. We also observed a reduction in intestinal length and volume with age. Age‐dependent transcriptomic profiling revealed significant changes in the expression of peripheral circadian clock genes and stem cell niche markers. Notably, the majority of these genes maintained their adult gene expression levels in old age following intermittent fasting during adulthood. Therefore, our results demonstrate that the decline in structural intestinal tissue homeostasis is associated with a decline in stem cell activity that can be counteracted by intermittent fasting. Since the intestinal mucosa of killifish is similar to that of mammals, the results of this study can be translated to general gut biology.