Tailoring the Health-Promoting Potential of Protein Hydrolysate Derived from Fish Wastes and Flavonoids from Yellow Onion Skins: From Binding Mechanisms to Microencapsulated Functional Ingredients.

Leontina Grigore-Gurgu,Oana Crăciunescu,Carmen Alina Bolea,Brîndușa Alina Petre,Gabriela Elena Bahrim,Andreea Iosăgeanu,Anca Oancea,Nicoleta Stănciuc,Iuliana Aprodu

doi:10.3390/biom10101416

Abstract

This study focuses on combining different bioprocessing tools in order to develop an in-depth engineering approach for enhancing the biological properties of two valuable food by-products, namely fish waste and yellow onion skins, in a single new bioactive formulation. Bone tissue from phytophagous carp (Hypophthalmichthys molitrix) was used to obtain bioactive peptides through papain-assisted hydrolysis. The peptides with molecular weight lower than 3 kDa were characterized through MALDI-ToF/ToF mass spectrometry and bioinformatics tools. As a prerequisite for microencapsulation, the ability of these peptides to bind the flavonoids extracted from yellow onion skins was further tested through fluorescence quenching measurements. The results obtained demonstrate a considerable binding potency with a binding value of 106 and also the presence of one single or one class of binding site during the interaction process of flavonoids with peptides, in which the main forces involved are hydrogen bonds and van der Waals interactions. In the freeze-drying microencapsulation process, an efficiency for total flavonoids of 88.68 ± 2.37% was obtained, considering the total flavonoids and total polyphenols from the powder of 75.72 ± 2.58 quercetin equivalents/g dry weight (DW) and 97.32 ± 2.80 gallic acid equivalents/g DW, respectively. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test on the L929 cell line cultivated in the presence of different concentrations of microencapsulated samples (0.05–1.5 mg/mL) proved no sign of cytotoxicity, the cell viability being over 80% for all the samples.

Highlights

The fish trade accounts for approximately 140 million tons of fish production, including aquaculture, out of which 110 million is for human consumption
The collagen type I α1 hydrolysis resulted in a total of peptides with molecular weights ranging from 360.45 to 21392.42 Da, whereas the hydrolysis of collagen type I α2 generated a mixture of peptides with molecular weights ranging from 561.59 to 8637.33 Da
A bidirectional approach was taken for bioprospecting targeted applications of two different food by-products, namely fish waste and yellow onion skins, for efficient formulations in order to increase the health-promoting properties

Summary

Introduction

The fish trade accounts for approximately 140 million tons of fish production, including aquaculture, out of which 110 million is for human consumption. The interest in producing fish hydrolysates has increased due to the value-added potential of the resulting peptides that can be used as functional ingredients for commercial food products [2]. The reuse of onion by-products in high-value functional and healthy ingredients may offer the opportunity to valorize these low-cost food by-products in economically interesting perspectives, exploiting their potential applications in functional foods, supplements, cosmetics, and nutraceutical products. This comes in a context in which consumers increasingly refuse synthetic food supplements, expressing their preferences for ingredients from natural sources with beneficial effects on health [7,8]. Quercetin is of great interest due to its antimicrobial and antioxidant activity, which are strongly related with a role in cancer prevention, inflammatory disorders, cardiovascular diseases [12], anti-inflammatory activity, antihistamine effect, allergy medication, anticancer and antivirus activities, and reducing blood pressure in hypertensive subjects [7]

Objectives

Methods

Results

Conclusion