Biosynthesis of γ-aminobutyric acid by lactic acid bacteria in surplus bread and its use in bread making

Abstract

Aims The aim of this study was to investigate the effectiveness of bread as substrate for γ‐aminobutyric acid (GABA) biosynthesis, establishing a valorization strategy for surplus bread, repurposing it within the food chain. Methods and Results Surplus bread was fermented by lactic acid bacteria (LAB) to produce GABA. Pediococcus pentosaceus F01, Levilactobacillus brevis MRS4, Lactiplantibacillus plantarum H64 and C48 were selected among 33 LAB strains for the ability to synthesize GABA. Four fermentation experiments were set up using surplus bread as such, added of amylolytic and proteolytic enzymes, modifying the pH or mixed with wheat bran. Enzyme‐treated slurries led to the release of glucose (up to 20 mg g−1) and free amino acid, whereas the addition of wheat bran (30% of bread weight) yielded the highest GABA content (circa 800 mg kg−1 of dry weight) and was the most suitable substrate for LAB growth. The selected slurry was ultimately used as an ingredient in bread making causing an increase in free amino acids. Conclusions Besides the high GABA concentration (148 mg kg−1 dough), the experimental bread developed in this study was characterized by good nutritional properties, highlighting the efficacy of tailored bioprocessing technologies as means to mitigate food wastage. Significance and Impact of Study Our results represent a proof of concept of effective strategies to repurpose food industry side streams.

Exploitation of wasted bread as substrate for polyhydroxyalkanoates production through the use of Haloferax mediterranei and seawater

“…The loss of bread occurs through the entire supply chain, from the bakery (for example the crust removed from sandwich bread, that can reach 40% of the entire production) ( Verni et al, 2020 ), to the distribution network and at household level. Nowadays, most of the leftover bread is disposed as waste and only a little amount of bread is reused, mainly as feed ( Verni et al, 2022 ). Different attempts for wasted bread valorization include the production of food ingredients, like glucose syrup ( Kwan et al, 2018 ; Riaukaite et al, 2019 ), or substrate for brewing ( Dlusskaya et al, 2008 ; Brancoli et al, 2020 ) or the production of functional ingredients for the bakery sector ( Immonen et al, 2020 ; Nionelli et al, 2020 ; Verni et al, 2022 ).…”

Reuse of Wasted Bread as Soil Amendment: Bioprocessing, Effects on Alkaline Soil and Escarole (Cichorium endivia) Production

“…The valorization of bakery waste as a food ingredient has been largely investigated recently, and different innovative biotechnological protocols have been proposed aiming at obtaining glucose syrup [ 27 , 28 ] or beer [ 26 , 29 ]. Recently, bioprocessing, e.g., enzymatic treatments and microbial fermentation, have been used to convert bread waste into valuable food ingredients, aiming at the improvement of the technological and sensory characteristics of the biomass, but also to the in situ enrichment of functional compounds such as dextran (with a positive impact on food texture) [ 30 ], antimicrobial compounds [ 31 ], and GABA [ 32 ].…”

“…In particular, the bioprocessed wasted bread harboured a very high population of the starter L. plantarum H64. The strain, previously selected for the ability to biosynthesize GABA in a matrix composed of wasted bread and wheat bran, allowed the repurpose of two of the main by-products of the cereal industry, promoting their application as a bread ingredient [ 32 ]. As expected, because of the starter carbohydrate metabolism, the bioprocessing enabled the production of organic acids which are in line with those previously reported in fermented surplus bread matrices [ 31 , 32 ].…”

“…The strain, previously selected for the ability to biosynthesize GABA in a matrix composed of wasted bread and wheat bran, allowed the repurpose of two of the main by-products of the cereal industry, promoting their application as a bread ingredient [ 32 ]. As expected, because of the starter carbohydrate metabolism, the bioprocessing enabled the production of organic acids which are in line with those previously reported in fermented surplus bread matrices [ 31 , 32 ]. On the contrary, proteolysis was not as pronounced if compared to common flour, which is explained by the fact that the proteases of the original flour, composing the bread dough, are degraded during the baking process.…”

“…Indeed, unlike dairy LAB, most sourdough lactobacilli do not possess a cell-envelope-associated proteinase and depend on cereal-associated proteinase [ 42 ]. Hence, in surplus bread matrices, to ease the release of peptides available during LAB fermentation for their catabolism to amino acids or small bioactive sequences, the use of proteases should be considered, as previously reported [ 31 , 32 ]. Although a decrease in the total free amino acid content was observed in bioprocessed wasted bread, GABA content was 28% higher in bWB compared to WB.…”