Two-stage selective enzymatic hydrolysis generates protein hydrolysates rich in Asn-Pro and Ala-His for enhancing taste attributes of soy sauce

• Published in: Food chemistry 2021-05, Vol.345, p.128803-128803, Article 128803
• Main Authors: Zhao, Yaqi, Zhao, Xuan, Sun-Waterhouse, Dongxiao, Ivan Neil Waterhouse, Geoffrey, Zhao, Mouming, Zhang, Jiahui, Wang, Fang, Su, Guowan
• Format: Article
• Language: English
• Subjects: Aminopeptidases - metabolism; Dipeptides - analysis; Peptide Hydrolases - metabolism; Plant Proteins - chemistry; Protein Hydrolysates - chemistry; Selective enzymatic hydrolysis; Soy Foods - analysis; Soy sauce; Taste; Taste-active peptide; Umami peptide; Umami-enhancing property
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2020.128803

•Some peptides in soy sauce elicit and enhance the umami taste of soy sauce.•Natural soy sauce has 10 umami-active peptides including Asn-Pro and Ala-His.•Asn-Pro and Ala-His exhibited significant umami taste and umami-enhancing property.•Two-stage selective enzymatic hydrolysis of non-soy sauce protein preparation was preferred.•The enzymatic hydrolysate rich in Asn-Pro or Ala-His enhanced soy sauce’s umami. This study demonstrated the contribution of peptides to umami soy sauce taste. Asn-Pro and Ala-His with remarkable umami taste and umami-enhancing capacity were found in original soy sauce, possessing umami thresholds of 175 and 160 mg/L and umami-enhancing thresholds of 10 and 13 mg/L, respectively. Firstly, an industrially viable two-stage hydrolysis at 55 °C (a 12-h hydrolysis with the neutral protease, then a 12-h hydrolysis with the aminopeptidase) was established to produce protein hydrolysates rich in umami-tasting and umami-enhancing peptides (e.g. Asn-Pro and Ala-His) from non-soy sauce protein preparations (soy protein isolate, rice proteins, wheat proteins, peanut proteins or pea proteins). The soy protein isolate hydrolysate produced via the two-stage hydrolysis had Asn-Pro and Ala-His contents 3.32 and 1.15 times higher than those produced via the one-stage hydrolysis using the neutral protease only. Adding the hydrolysate to original soy sauce at 5% w/v significantly increased umami and reduced bitterness.