Combined Remediation and Protein Production Using Microalgae Growth on Waste Bakery Products

Abstract

A new concept of bakery industry waste use as a nutrient source for the production of proteins by microalgae growth has been developed. The proposed ideas provide an innovative approach to establish a system to valorise bakery industry waste, more specifically, the so-called waste ´biscuits flour´, and to produce rich protein algal biomass, which could potentially be applied in feed industry. Biscuits flour was used as carbon and nutrients source in mixotrophic growth of Chlorella sorokiniana, pure culture, and a mixed culture of microalgae taken from a natural environment. The feasibility of utilizing bakery waste, raw and hydrolysate, for algal biomass production was investigated and compared with the growth of the microalgae in WARIS-H medium and in natural water. Although better biomass growth is achieved with hydrolysed flour, highest concentration of proteins were obtained for C. sorokiniana and the mixed culture, 34.63 and 24.06% respectively, when the waste flour is not hydrolised at the beginning of the assay. These figures contrast with the lower protein content in both cultures, 3.63 and 8.94%, respectively, when WARIS-H medium and natural water are used as nutrient sources. These good preliminary results, together with a situation in which the supply of raw materials for livestock and farmed fish is beginning to become critical, give rich-protein microalgae production increasing relevance as a source of feed.