การผลิตและสมบัติของส่วนผสมเชิงหน้าที่จากโปรตีนไข่น้ำ (Wolffia Globosa) โดยวิธีการดัดแปรด้วยเอนไซม์

Abstract

Plant-based proteins have received considerable attention by nowadays consumers. Khai-nam (Wolffia Globosa) is a traditional Thai plant that that has long been consumed and recognized as a rich source of nutrients particularly protein content. Moreover, it has a fast growth rate and can tolerate extreme conditions. Therefore, it becomes one of the potential sources of alternative protein. This research aimed to optimize the extraction condition for Khai-nam protein using ultrasonic assisted extraction (UAE). Three independent variables including solid-liquid ratio (X1, 30-40 ml/g), extraction time (X2, 10-30 min), and sonication amplitude (X3, 60-80 %) were studied. The protein extraction yield of each treatment was monitored as a response value. Afterwards, the derived protein concentrate was characterized and hydrolyzed using commercial enzymes including Alcalase and Protamex at degree of hydrolysis of 3, 6 and 9 %. The effect of enzymatic modification on protein properties including protein pattern, change of protein secondary structures, functional properties, antioxidant activities and inhibitory effects on human cancer cells was investigated. The optimal condition consisted of 30:1 liquid-solid ratio (ml of distilled water/ g Khai-nam), extraction time of 25 min and 78% sonication amplitude, achieving 14.13±1.20% protein extraction yield (51.33 ± 0.13%. protein content). According to the amino acid profile, leucine, valine, and phenylalanine were the major amino acids in Khai-nam protein concentrates; moreover, its protein digestibility was about 57.52±1.70 %. The molecular weight of protein hydrolysates prepared by using Protamex and Alcalase at degree of hydrolysis (DH) of 3, 6 and 9% ranged between <10 and 61.5 kDa. The enzymatic hydrolysis caused the secondary structural transformations of proteins from β-sheets and random coils to α-helices and β-turns. In addition, the protein solubility was significantly enhanced as the increased degree of hydrolysis (p<0.05). The foaming activity and foaming stability of protein hydrolysate prepared by Alcalase at 3% of degree of hydrolysis were highest (55.00 ± 0.00 % และ 33.33 ± 1.86 %). On the other hand, emulsifying stability, and oil binding capacity tended to decrease with increasing hydrolysis degree. Interestingly, the protein concentrate showed higher DPPH scavenging activity and FRAP than protein hydrolysates. Protein hydrolysate prepared by Protamex with 6% degree of hydrolysis had the strongest ABTS radical scavenging activity (15.26±0.27 µmol Trolox eq. /g sample); meanwhile hydrolysate with 3% degree of hydrolysis had the highest potential to chelate metal ion (2.09 ± 0.10 µmol EDTA eq. /g. sample). Moreover, protein hydrolysates show a potential on inhibiting human ovarian cancer cell lines (SK -OV-3 and A2790), while it was not toxic to a normal cell line (hepatic stellate). This research can be concluded that the application of ultrasonic-assisted extraction successfully produced the alternative protein from Wolffia Globosa. Moreover, the enzymatic hydrolysis can be used to modify the functional properties and bioactivities of protein for producing a functional ingredient.