RT info:eu-repo/semantics/doctoralThesis
T1 Estudio de los procesos enzimáticos y fermentativos para la reintroducción de pan desechado en la cadena alimentaria
A1 Sigüenza Andrés, Teresa
A2 Universidad de Valladolid. Escuela de Doctorado
K1 Probióticos
K1 Functional beverage
K1 Bebida funcional
K1 Fermentation
K1 Fermentación
K1 Discarded bread
K1 Pan deshechado
K1 Probiotics
K1 Probióticos
K1 3309 Tecnología de Los Alimentos
AB According to the FAO, one-third of food produced for human consumption is lost or wasted annually, leading to significant economic, social, and environmental consequences. Institutions and governments are implementing strategies to reduce food waste to address this issue, aligning with Sustainable Development Goal 12.3 of the United Nations’ 2030 Agenda. The European Commission promotes reducing food waste by reintegrating food by-products into the human food chain, transforming them into valuable compounds.Since bread and bakery products are among the most discarded foods, after fruits and vegetables, this doctoral thesis explores enzymatic and fermentative processes to reintroduce discarded bread into the food supply chain. The research focuses on developing high-value products such as glucose-rich bread hydrolysate and a non-alcoholic, functional fermented beverage.The first phase of the study investigated the enzymatic hydrolysis of bread using α-amylase and glucoamylase, as bread starch, once gelatinized, is an ideal substrate for enzymatic breakdown. The process was optimized by analyzing the effects of pH and temperature to maximize sugar production.A response surface methodology was used to improve liquefaction and saccharification separately, and then both were studied simultaneously. The most efficient approach was simultaneous hydrolysis, achieving higher glucose concentration in less time. The optimal conditions were a pH of 4.51 and a temperature of 64.7°C. These conditions reduced costs, energy consumption, and processing time while increasing the efficiency of food waste utilization. The resulting glucose hydrolysate can serve as a sugar substitute in various food applications.The second phase examined the potential of bread hydrolysate as a substrate for lactic acid bacteria (LAB) and Bifidobacterium fermentation. Three experimental variables were studied: the commercial lactic cultures used, including the LGG starter (Lacticaseibacillus rhamnosus GG) and the mixed BY starter (Bifidobacterium animalis subsp. lactis, Lactobacillus delbrueckii subsp. bulgaricus, and Streptococcus thermophilus), the enzymatic hydrolysis (E or NE), and the desalting (DS or S) of the bread flour and water mixture at 20% (w/v).Several parameters were evaluated, including microbial growth, pH, acidity, carbohydrate concentration, organic acids, volatile compounds, water-holding capacity (WHC), and acidification kinetics. Sensory analysis and shelf-life assessment were also conducted.The combination of enzymatic hydrolysis, salt, and LGG resulted in the most effective fermentation process, ensuring better acidification and product stability. Although LGG performed better in terms of fermentation efficiency, the BY starter produced beverages with higher consumer acceptance, particularly regarding texture and flavor.Desalting had a negative impact on microbial metabolism, resulting in higher pH levels and lower acidification rates, likely due to the reduced availability of essential minerals. Conversely, enzymatic hydrolysis improved fermentation by lowering pH, increasing acidity, and enhancing carbohydrate availability, thereby supporting greater microbial growth. During storage, enzyme-treated samples maintained lower pH and higher acidity levels, whereas untreated samples exhibited slight pH increases.The final fermented beverage contained organic acids, particularly lactic and acetic acids, at levels sufficient to ensure microbiological safety. Volatile compounds such as ethanol, acetic acid, acetoin, and diacetyl were also detected. Acetoin and diacetyl, responsible for yogurt and butter-like aromas, were more prominent in enzyme-treated samples.Additionally, the fermentation process facilitated the production of γ-aminobutyric acid (GABA), a bioactive compound with potential health benefits.The results demonstrate that enzymatic and fermentative processes effectively valorize bread waste, producing a microbiologically safe, nutritionally rich, and sensory-appealing beverage. This research contributes to the fight against food waste while offering an innovative alternative in the food and beverage industry.
YR 2024
FD 2024
LK https://uvadoc.uva.es/handle/10324/76346
UL https://uvadoc.uva.es/handle/10324/76346
LA spa
NO Escuela de Doctorado
DS UVaDOC
RD 19-jul-2025