Evaluating the Potential of the Defatted By-Product of Aurantiochytrium sp. Industrial Cultivation as a Functional Food.

João Reboleira,Narcisa M Bandarra,Rafael Félix,Rogério Mendes,Carina Félix,Marco F L Lemos,Carlos M Silva,Bárbara Teixeira,Maria C Paulo,Marcelo M R De Melo,Joana Coutinho,Jorge A Saraiva

doi:10.3390/foods10123058

Abstract

While Aurantiochytrium sp. is an increasingly popular source of polyunsaturated fatty acids (PUFAs), its extraction generates high amounts of waste, including the spent, defatted residue. The composition and bioactivities of this by-product could prove to be a major part of the sustainable valorisation of this organism within the framework of a circular economy. In this study, the defatted biomass of commercial Aurantiochytrium sp. was nutritionally characterised, and its amino acid profile was detailed. Additionally, the antioxidant and prebiotic potentials of an enzymatically digested sample of defatted Aurantiochytrium sp. were evaluated under a set of miniaturised in vitro assays. The nutritional profile of the spent Aurantiochytrium biomass revealed a protein and dietary-fibre rich product, with values reaching 26.7% and 31.0% for each, respectively. It also held high concentrations of glutamic and aspartic acid, as well as a favourable lysine/arginine ratio of 3.73. The digested samples demonstrated significant Weissela cibaria and Bifidobacterium bifidum growth-enhancing potential. Residual ferric reducing antioxidant power (FRAP) activity was likely attributed to antioxidant amino acids or peptides. The study demonstrated that some of the nutritional and functional potential that reside in the defatted Aurantiochytrium sp. waste encourages additional studies and the development of food supplements employing this resource’s by-products under a biorefinery framework.

Highlights

Aurantiochytrium sp. is a Thraustochytrid that has recently gained attention due to its high production of eicosapentaenoic acid and docosahexaenoic acid
The protein content is within the expected values for cultured Aurantiochytrium sp., with authors such as Sami et al (2013) and Moran et al (2019) reporting this parameter at around 15% [38,39]
Aurantiochytrium sp. biomass, which is a significant part of the industrial waste associated with the production of high added-value polyunsaturated fatty acids (PUFAs) from this source

Summary

Introduction

Aurantiochytrium sp. is a Thraustochytrid that has recently gained attention due to its high production of eicosapentaenoic acid and docosahexaenoic acid. A vast array of strategies and applications have been tested far in an attempt to add value to otherwise discarded microbial waste, with a large focus on the recycling of nutrients as a substrate for other economically feasible fermentations as well as the recovery of bioactive products [3,4,5] Authors such as Medina (2015), Aida (2017), and Deshmukh (2021) have published distinct valorisation strategies applied to defatted microalgal or Thraustochytrid biomass, including the use as functional ingredients in biodegradable films, extraction of protein-rich antioxidant fractions, and direct use as nitrogen and phosphorous-rich additives to biofuel substrates [4,6,7]. The use of spent microalgal biomass has been extended to livestock feed as either a soy or corn replacement as well as a nutritional supplement to traditional mixes [8]

Methods

Results

Conclusion