Effects of yeast fermentation on transforming the volatile compounds of unsalted pork hydrolysate

Abstract

This study investigated the possibility of transforming unsalted pork hydrolysate into a liquid seasoning by studying volatile compound production through yeast fermentation. The yeasts used included a typical soya sauce yeast and three wine yeasts. The yeasts inoculated in the glucose supplementary pork hydrolysate increased by approximately 2.0 log of CFU mL À1 within 24 hours at 30°C without adding salt. Yeast fermentation largely depleted the abundant aldehydes (hexenal) present in unfermented pork hydrolysate to trace levels with the formation of ethanol, corresponding alcohols and carboxylic acids. The wine yeasts showed higher production of fruity esters such as ethyl acetate and isoamyl acetate, whereas the soya sauce yeast produced more ketones such as acetone and 2-heptanone. This study revealed a potential method of producing a value-added meat hydrolysate from pork by-product.

Modulation of aroma compounds in yeast and lactic acid bacterium co‐fermented pork hydrolysates by thermal treatment and addition of aroma precursors (cysteine and xylose)

“…The free amino acids were extracted using the same method as reducing sugars extraction as described in Section 2.5. The identification and quantitative analysis were performed using the same method as described in Li et al ., 2021b. The results are expressed as mg/100 mL.…”

“…The free amino acids were extracted using the same method as reducing sugars extraction as described in Table 1 The amount of xylose and cysteine added to sequentially fermented pork hydrolysates (S) and their respective names in this study Section 2.5. The identification and quantitative analysis were performed using the same method as described in Li et al, 2021b. The results are expressed as mg/100 mL.…”

“…2-Pentylfuran is a common compound derived from linoleic acid oxidation and imparts fruity, green and vegetable aroma (Xu et al, 2011). This volatile is often reported to be naturally present in the raw pork due to mammalian metabolism (Li et al, 2021b), but was degraded during the thermal treatment. In addition, Dhakal et al (2017) and Eric et al (2014) suggested that furan formation was highly linked to higher temperatures and longer time during the heat treatment of foods, while pressure treatment at ambient temperature did not seem to promote its production.…”

“…The detailed procedure of pork hydrolysate fermentation was described in Li et al (2021bLi et al ( , 2021c with some modifications. Briefly, 2% (w/v) of glucose was added to the pork hydrolysate as a carbon source to support the growth of microorganisms, and the mixture was pasteurised at 90 °C for 15 min.…”

“…In this context, the conversion of pork trimmings into flavouring agents could be conducted by co-culturing Lactobacillus fermentum PCC and Pichia kluyveri FrootZen. The effect of these two strains on the volatile formation in pork hydrolysate was investigated in monocultures in our previous studies (Li et al, 2021b(Li et al, , 2021c.…”