Avaliação das propriedades funcionais e estruturais de hidrolisados de diferentes colágenos bovinos obtidos por hidrólise enzimática assistida por ultrassom

Abstract

The objective of this study was to evaluate the functional and structural properties of different bovine collagen hydrolysates obtained through ultrasound assisted enzymatic hydrolysis. Six different samples of commercial bovine collagen were used in the hydrolyses: fiber, powder fiber, hydrolysate1, hydrolysate 2, gelatin 1 and gelatin 2 along with three different enzymes: Alcalase®, Flavourzyme® and pepsin. The analyses carried out were: physical-chemical, structural composition (Fourier transform infrared spectroscopy), hydrolysis degree, antioxidant and antimicrobial activity. Significant difference (p<0.05) was found for humidity, ashes, proteins, lipids, pH, hydroxyproline and collagen in the different crude samples. The use of previous or simultaneous ultrasound strengthened the enzymatic hydrolysis of the samples, generating larger number of bands in wave numbers (cm-1). Regarding the use of the enzyme Alcalase®, the enzymatic hydrolysis (16% enzyme) and previous ultrasound, applied to the samples (except for the fiber and powder fiber samples) resulted in lower residual protein content, higher hydrolysis degree and higher antioxidant activity. The hydrolysate 1 sample presented the lowest residual protein content (7.06 mg/mL), while hydrolysate 2 presented the highest hydrolysis degree (10.3%) and the gelatin 1 sample had the highest antioxidant activity (66.2%). When using the enzyme Flavouzyme®, the enzymatic hydrolysis and simultaneous ultrasound led to lower residual protein content and higher hydrolysis degree, and the hydrolysate 1 sample was the one with the highest antioxidant activity (52.2%) in the treatment that used enzyme only. When the enzyme pepsin was employed, the hydrolysate 1 sample presented the lowest residual protein content (4.50 mg/mL), while the Fiber sample had the highest hydrolysis degree value (21.7%) and the gelatin 2 sample showed the highest antioxidant activity value (53.7%). The lowest residual protein content resulted from the higher hydrolysis of the protein structure of the samples, due to the different treatment components. The samples that suffered highest rupture of their peptide bonds presented higher hydrolysis degree. The hydrolysates with the highest hydrolysis degree values not always presented good values of antioxidant activity, since the generation of high functionality peptides is what determines these values. Previous ultrasound worked better than the simultaneous one when the enzyme Alcalase® was used, applying a 16% concentration to the substrate. For the enzyme Flavourzyme®, the use of ultrasound did not result in significant difference in the results obtained. The enzyme Alcalase® provided the highest antioxidant activity values, while the enzyme Flavourzyme® presented the highest hydrolysis degree values, and pepsin showed the lowest residual protein average. The hydrolysates obtained from the treatments with the enzyme pepsin in the hydrolysis presented the highest inhibiting action against the bacteria Salmonella choleraesuis and Staphylococcus aureus in lower-than-10% concentrations. Therefore, enzymes and different ultrasound applications were concluded to provide higher structural rupture of samples and increase in the functionality of different bovine collagen hydrolysates (antioxidant and antimicrobial activities).