Browsing by Subject "bread waste"
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(2020)Wheat bread is one of the most discarded food at the global level. To fulfill the goals of waste reduction and increase the circular economy activities, the re-utilization of bread still fit for food in the food chain is a priority. However, the utilization of wheat bread waste in the food chain is challenging. Lactic acid bacteria (LAB) fermentation has been recently studied as a potential processing method for bread waste slurry and applied as a dough ingredient in bread production. In LAB fermentation, functional and bioactive compounds can be produced. Some LAB strains can produce γ-aminobutyric acid (GABA), a neurotransmitter in animals’ central nervous system with multiple physiological functions. GABA has received much attention due to its numerous beneficial bioactivities. Currently, information on GABA biosynthesis by LAB fermentation in bread substrate is not available. In this thesis, the effects of LAB strain selection and fermentation substrates in waste bread fermentation were studied. Four different fermentation trials using wheat bread as substrate were performed to select the best LAB strain, optimize bread matrix composition, and fermentation parameters for GABA production. Microbial growth, pH, total titratable acidity, organic acids (High Performance Liquid Chromatography ), sugar composition (High-Performance AnionExchange Chromatography and Pulsed Amperiometric Detection), and GABA content were assessed. Among the conditions tested, the addition of wheat bran as a nutrient source improved the GABA production most significantly. Thus, this condition was upscaled for bakery uptake and used in a baking trial to produce value-added bread containing GABA. LAB fermentation of waste bread to produce functional bioactive compounds was proven to be a potential processing method applicable to bakery products. The combination of two food sidestreams, waste wheat bread and wheat bran, can be implemented as a strategy to re-utilize food by-products in the food chain.
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(2020)The literature review deals with the status and the causes of bread waste all over the world. More importantly, the current managements of increasing bread waste. Enzymatic hydrolysis by α-amylase and amyloglucosidase is a potential treatment, which transforms bread waste into syrups for further revaluation with functional compounds. The aim of the experimental work was to determine the influence of enzymatic hydrolysis conditions (hydrolysis time, hydrolysis temperature, enzyme dosage of α-amylase and amyloglucosidase) on glucose content and free amino nitrogen (FAN) content of resulting hydrolysate from bread waste. Furthermore, the effect of lactic acid fermentation on glucose content was studied when bread waste was subjected to simultaneous hydrolysis and fermentation with Pediococcusclaussenii (E-032355T). Glucose content varied greatly under different hydrolysis conditions from nearly 17% to only 5%, while FAN content was barely influenced. pH value had slight changes and no Bacillus cereus bacteria was found. A well fitted model for glucose content was obtained with an excellent power of interpretation, prediction and optimization. Enzyme dosage was the principal factor having a significant effect on hydrolysis efficiency, followed by temperature and time. With optimized hydrolysis conditions (50 mg/kg α-amylase and 2500 mg/kg amyloglucosidase, 30℃, 19 hours), the glucose content 16.31% was achieved, and the result was in accordance with the value 16.39% predicted by the model. Moreover, a 2.2% increase of glucose yield was detected when waste bread was subjected to simultaneous hydrolysis and fermentation compared to the control sample (bread waste was treated only with hydrolysis under the same condition). The well growth of used lactic acid bacteria (LAB) strains Pediococcusclaussenii (E-032355T) resulted in lower pH, which further improved enzymes activities and increased glucose content of the hydrolysate.
Now showing items 1-2 of 2