Water distribution and key aroma compounds in the process of beef roasting

Comparative analysis of the nutritional composition and volatile compounds in male and female adults, nymphs, and molts of Eupolyphaga sinensis Walker

ABSTRAC

Female adult Eupolyphaga sinensis Walker (FAESW) has traditionally been a food source in Southeast Asian countries such as China and India, due to its rich nutritional content. However, the nutritional value of male adults (MAESW) and its molts (MESW) has hardly been reported. Therefore, this study aims to explore the potential application of MAESW and MESW in food by investigating and comparing their nutritional composition (i.e., protein, amino acids, fatty acids, and essential elements) with traditional sources of nutrition. The protein content of MAESW and MESW was 66.10 ± 0.49% and 59.86 ± 6.07%, respectively, and the highest energy content (462.26 ± 1.28 kcal/100 g) was observed for MAESW. Eight essential amino acids were determined, of which the males and MESW were found to have higher contents than those of FAESW (p < 0.05). Oleic and linoleic acid contents were higher in the adults than nymphs. Moreover, MESW was predominant in calcium (6770.84 mg/kg), whereas MAESW was rich in iron (556.12 mg/kg). Likened to chicken, the protein, amino acid, fatty acid, and mineral contents of ESW were higher. The volatiles of ESW were related to hexaldehyde, benzaldehyde, acetic acid, and butyric acid. This study provides a better understanding of the chemical composition of ESWs during their growth cycle and helps optimize information on edible insects, promoting their use as a potential food source for humans.

PRACTICAL APPLICATION

As a kind of edible insect, the utilization of adult male Eupolyphaga sinensis Walker (ESW) and its molt is very low at present. Therefore, this study examined the nutrients and volatile substances of ESW (at different growth stages) and molt, which provided a theoretical basis for the subsequent development and utilization of ESW.

Insights into the Flavor Profile of Yak Jerky from Different Muscles Based on Electronic Nose, Electronic Tongue, Gas Chromatography-Mass Spectrometry and Gas Chromatography-Ion Mobility Spectrometry

It is well known that different muscles of yak exhibit distinctive characteristics, such as muscle fibers and metabolomic profiles. We hypothesized that different muscles could alter the flavor profile of yak jerky. Therefore, the objective of this study was to investigate the differences in flavor profiles of yak jerky produced by longissimus thoracis (LT), triceps brachii (TB) and biceps femoris (BF) through electronic nose (E-nose), electronic tongue (E-tongue), gas chromatography-mass spectrometry (GC-MS) and gas chromatography-ion mobility spectrometry (GC-IMS). The results indicated that different muscles played an important role on the flavor profile of yak jerky. And E-nose and E-tongue could effectively discriminate between yak jerky produced by LT, TB and BF from aroma and taste points of view, respectively. In particular, the LT group exhibited significantly higher response values for ANS (sweetness) and NMS (umami) compared to the BF and TB groups. A total of 65 and 47 volatile compounds were characterized in yak jerky by GC-MS and GC-IMS, respectively. A principal component analysis (PCA) model and robust principal component analysis (rPCA) model could effectively discriminate between the aroma profiles of the LT, TB and BF groups. Ten molecules could be considered potential markers for yak jerky produced by different muscles, filtered based on the criteria of relative odor activity values (ROAV) > 1, p < 0.05, and VIP > 1, namely 1-octen-3-ol, eucalyptol, isovaleraldehyde, 3-carene, D-limonene, γ-terpinene, hexanal-D, hexanal-M, 3-hydroxy-2-butanone-M and ethyl formate. Sensory evaluation demonstrated that the yak jerky produced by LT exhibited superior quality in comparison to that produced by BF and TB, mainly pertaining to lower levels of tenderness and higher color, taste and aroma levels. This study could help to understand the specific contribution of different muscles to the aroma profile of yak jerky and provide a scientific basis for improving the quality of yak jerky.

Evaluation of key aroma compounds and protein secondary structure in the roasted Tan mutton during the traditional charcoal process

The traditional charcoal technique was used to determine the changes in the key aroma compounds of Tan mutton during the roasting process. The results showed that the samples at the different roasting time were distinguished using GC-MS in combination with PLS-DA. A total of 26 volatile compounds were identified, among which 14 compounds, including (E)-2-octenal, 1-heptanol, hexanal, 1-hexanol, heptanal, 1-octen-3-ol, 1-pentanol, (E)-2-nonenal, octanal, 2-undecenal, nonanal, pentanal, 2-pentylfuran and 2-methypyrazine, were confirmed as key aroma compounds through the odor activity values (OAV) and aroma recombination experiments. The OAV and contribution rate of the 14 key aroma compounds were maintained at high levels, and nonanal had the highest OAV (322.34) and contribution rate (27.74%) in the samples after roasting for 10 min. The content of α-helix significantly decreased (P < 0.05), while the β-sheet content significantly increased (P < 0.05) during the roasting process. The content of random coils significantly increased in the samples roasted for 0-8 min (P < 0.05), and then no obvious change was observed. At the same time, β-turn content had no obvious change. Correlation analysis showed that the 14 key aroma compounds were all positively correlated with the content of α-helix and negatively correlated with the contents of β-sheet and random coil, and also positively correlated with the content of β-turn, except hexanal and 2-methypyrazine. The results are helpful to promoting the industrialization of roasted Tan mutton.