Effect of lactic acid bacterial fermentation on amino acids and volatile compounds of pork trimming hydrolysate

Abstract

The objective of this research was to improve the volatile flavour profile of a pork trimming hydrolysate by lactic acid bacteria (LAB) fermentation. Five probiotic strains and one dairy strain were used. The dominant aliphatic aldehydes (80.90%) in the unfermented hydrolysate were greatly reduced to <15% by converting into respective carboxylic acids and alcohols after fermentation. Strain GG was the only LAB that produced a significant level of succinic acid (1.62 mg mL À1) and ketones (14.92%) (mainly diacetyl and acetoin) in the hydrolysate. Strains 299V and GG showed moderate proteolytic activities as their amino acid content reduced to 126.05 and 219.14 mg per 10 mL compared to the control (316.45 mg per 10 mL) after fermentation, respectively. However, little amino acid-derived volatiles were found in all fermented samples. These findings indicate that LAB fermentation modulates the flavour compounds of pork hydrolysates, which has the potential to be developed to novel flavouring materials.

Effect of co‐fermentation and sequential fermentation of Candida versatilis and Lactococcus lactis subsp. cremoris on unsalted pork hydrolysates components

“…Cremoris and C. versatilis showed proteolytic activities by producing more amino acids than utilising them. These results are in line with the study of Li et al (2021b), as L. lactis is a widely used as dairy lactococcal starters and demonstrated promising proteolytic activity. Although single C. versatilisinoculated samples showed an increase in the total amino acids content, this increase was not significant (Table 1).…”

“…cremoris DSM20069 were purchased from DSMZ (Braunschweig, Germany). The activation of the yeast and LAB strains was performed as described in Li et al (2021aLi et al ( , 2021b. In brief, the yeast was activated in yeast-malt broth (Oxoid, Basingstoke, UK) at 30 °C for 48 h, whilst the LAB strain was activated in MRS (De Man, Rogosa and Sharpe) broth (Oxoid) at 37 °C for 24 h. The activated cultures were preserved in 30% sterile glycerol (Merck, Darmstadt, Germany) and stored at À80 °C.…”

“…The proximate composition of the pork material before and after hydrolysis was described in Li et al (2021c). The commercial protease used, and the hydrolysis conditions were described in Li et al (2021b). Briefly, Flavourzyme Ò 500 MG (Novozymes, Copenhagen, Denmark) and pork trimmings at a ratio of 6.58:100 (enzyme/substrate by weight) were added to a blue-cap Duran Ò bottle with cap-sealed to hydrolyse the raw pork at 50 AE 1.0 °C for 6 h. At the end of hydrolysis, the bottles were heated at 85 °C for 15 min to deactivate the enzyme activities and to pasteurise the pork hydrolysates.…”

“…These compounds gave the fermented pork hydrolysates overall fruity, floral, sweet and 'soy sauce-like' notes. Besides, Li et al (2021b) reported L. lactis subsp. cremoris DSM20069, a LAB that is commonly applied in cheese fermentation, showed good proteolytic activity by producing more free amino acids in the hydrolysates, as well as producing acids, alcohols and ketones, which converted the unfermented pork hydrolysates to a potential meat-based flavouring.…”

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

“…The moisture of the raw meat was around 75%, with fat, protein and ash contents of about 2.25%, 21.5% and 1% (wet weight basis), respectively. The detailed preparation procedure of the pork hydrolysate used in this study was described in Li et al, (2020).…”