Development of a post-processing method to reduce the unique off-flavor of Allomyrina dichotoma: Yeast fermentation

Effect of yeast (Saccharomyces cerevisiae) fermentation on conformational changes in pig liver proteins and their ability to bind to characteristic aldehydes

This study aimed to explore the potential of a fermentation technology to reduce off-flavour perception and its underlying mechanisms. Results revealed that yeast fermentation (YF) significantly ameliorated the off-flavour of pig liver (p < 0.05). Specifically, YF pre-treatment decreased the relative abundance of α-helix and fluorescence intensity while increasing the surface hydrophobicity and SS level and loosening the microstructure of myofibrillar proteins (MPs) in pig liver. Additionally, the appropriate fermentation treatments enhanced the MP-aldehyde binding capacity by 0.25-1.30 times, demonstrating that YF-induced conformational modifications in pig liver proteins made them more prone to interacting with characteristic aldehydes. Moreover, molecular docking results confirmed that hydrophobic interactions are the primary drivers of MP-aldehyde binding. These findings suggest that YF technology holds immense promise for modulating off-flavour perception in liver products by altering protein conformation.

Changes in the characteristic volatile aromatic compounds in tuna cooking liquid during fermentation and deodorization by Lactobacillus plantarum RP26 and Cyberlindnera fabianii JGM9-1

Tuna cooking liquid has unpleasant aroma. In our previous studies, Cyberlindnera fabianii JGM9-1 and Lactobacillus plantarum RP26 demonstrated the ability to degrade this unpleasant aroma. However, the mechanism of microbial deodorization remains unclear. In this study, tuna cooking liquid was fermented using JGM9-1 alone, RP26 alone, and a combination of both strains. Changes in volatile aromatic compounds during fermentation were analyzed using HS-SPME-GC/MS. The unpleasant aroma of tuna cooking liquid were nine characteristic aromatic compounds associated with fishy, stinky, and greasy aromas. Furthermore, we found that the fermentation of microbes removed these unpleasant aromatic compounds and replaced them with pleasant aromatic compounds that contributed to fruity, grassy, and floral aromas. Finally, we screened 21 strong pairwise correlations between the production and consumption of characteristic volatile aromatic compounds by RP26 and JGM9-1, through HCA, VIP, OAV and Spearman's pairwise correlation analysis. These results help to clarify the metabolic mechanisms of microbial deodorization in tuna cooking liquid.

The regulation of key flavor of traditional fermented food by microbial metabolism: A review

The beneficial microorganisms in food are diverse and complex in structure. These beneficial microorganisms can produce different and unique flavors in the process of food fermentation. The unique flavor of these fermented foods is mainly produced by different raw and auxiliary materials, fermentation technology, and the accumulation of flavor substances by dominant microorganisms during fermentation. The succession and metabolic accumulation of microbial flora significantly impacts the distinctive flavor of fermented foods. The investigation of the role of microbial flora changes in the production of flavor substances during fermentation can reveal the potential connection between microbial flora succession and the formation of key flavor compounds. This paper reviewed the evolution of microbial flora structure as food fermented and the key volatile compounds that contribute to flavor in the food system and their potential relationship. Further, it was a certain guiding significance for food industrial production.

Aroma characterization and consumer acceptance of four cookie products enriched with insect (Ruspolia differens) meal

This research aims to advance knowledge on the impact of four processing methods on volatile compounds from insect-based baked products (cookies) to provide insights on consumer acceptance. Samples were exposed to double step enzyme digestive test, volatiles characterized through headspace analysis, while semi-trained panelists were recruited for the sensory test. Blanched and boiled samples of R. differens had considerably higher digestibility (83.42% and 81.61%, respectively) (p < 0.05) than toasted and deep-fried samples. Insect-based cookie products integrated with blanched and boiled R. differens meal expressed higher digestibility (80.41% and 78.73%, respectively) that was comparable to that of commercial cookie products (control cookies-CTRC with 88.22%). Key volatile compounds common between the various cookie products included, nonanal, octanal, methyl-pyrazine, hexanal, tetradecane, 2-pentylfuran, 2-heptanone, 2E-octenal, 2E-heptenal and dodecane. Among the volatile compounds, pleasant aromas observed were 2E,4E-dodecadienal, pentanal, octanal, methyl pyrazine, furfurals, benzaldehyde, and 2-pentyl furan, which were more pronounced in cookies fortified with boiled, toasted and deep-fried R. differens meal. There was a greater resemblance of sensory characteristics between control cookies and those fortified with deep-fried R. differens. These findings underscore the significant influence of aroma compounds on consumer acceptability and preference for insect-based baked food products, which allows for future process-modification of innate aromas of insect-based meals to produce high-valued pleasant consumer driven market products.

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.