Bread waste - A potential feedstock for sustainable circular biorefineries

Postbiotics in the Bakery Products: Applications and Nutritional Values

In recent years, the consumption of postbiotics has gained significant attention due to their potential health benefits. However, their application in the bakery industry remains underutilized. This review focuses on recent advances in the use of postbiotics, specifically the metabolites of lactic acid bacteria, in bakery products. We provide a concise overview of the multifaceted benefits of postbiotics, including their role as natural antioxidants, antimicrobials, and preservatives, and their potential to enhance product quality, extend shelf-life, and contribute to consumer welfare. This review combines information from various sources to provide a comprehensive update on recent advances in the role of postbiotics in bakery products, subsequently discussing the concept of sourdough as a leavening agent and its role in improving the nutritional profile of bakery products. We highlighted the positive effects of postbiotics on bakery items, such as improved texture, flavor, and shelf life, as well as their potential to contribute to overall health through their antioxidant properties and their impact on gut health. Overall, this review emphasizes the promising potential of postbiotics to revolutionize the bakery industry and promote healthier and more sustainable food options. The integration of postbiotics into bakery products represents a promising frontier and offers innovative possibilities to increase product quality, reduce food waste, and improve consumer health. Further research into refining techniques to incorporate postbiotics into bakery products is essential for advancing the health benefits and eco-friendly nature of these vital food items.

Understanding the Utilization of Wasted Bread as a Brewing Adjunct for Producing a Sustainable Wheat Craft Beer

Wasted bread (WB) has been studied as an alternative ingredient for increasing the sustainable footprint in the beer production chain. There are gaps in the literature on the impact of WB on beer manufacturing. Thus, the objective was to evaluate the addition of WB as a replacement for wheat flakes in a craft beer. Three formulations with different concentrations of WB were produced and monitored for glucose and maltose concentrations in the mash; the beer was analyzed for ethanol, glycerol, acetic acid, lactic acid, pH, acidity, turbidity, color, and volatile compounds. Sensory analysis was performed by a trained panel. In the initial stages of mashing, a higher concentration of sugars was found in the wort with WB added, while, at the end stages, this was higher in the control wort. The addition of WB resulted in beers with a lower turbidity, darker color, and lower concentrations of ethanol, glycerol, and acetic acid. Among the volatile compounds, D-limonene, ethyl dodecanoate, heptanol, acetaldehyde, and ethyl acetate should be further explored as markers for the presence of WB. Higher intensities of banana odor and flavors were observed by the trained panel when there was a greater substitution of wheat flakes. WB is a low-cost and effective ingredient for beer production, although more work is needed for its large-scale use.

Synthetic biology approaches and bioseparations in syngas fermentation

Fossil fuel use drives greenhouse gas emissions and climate change, highlighting the need for alternatives like biomass-derived syngas. Syngas, mainly H2 and CO, is produced via biomass gasification and offers a solution to environmental challenges. Syngas fermentation through the Wood-Ljungdahl pathway yields valuable chemicals under mild conditions. However, challenges in scaling up persist due to issues like unpredictable syngas composition and microbial fermentation contamination. This review covers advancements in genetic tools and metabolic engineering to expand product range, highlighting crucial enabling technologies that expedite strain development for acetogens and other non-model organisms. This review paper provides an in-depth exploration of syngas fermentation, covering microorganisms, gas composition effects, separation techniques, techno economic analysis, and commercialization efforts.

Successful combination of lactic acid bacteria and yeast fermentation and enzymatic treatment to re-cycle industrial bread by-products for bread making

Bread industry generates significant amounts of by-products which are discarded every day with relevant economic and environmental repercussions, despite they still contain high concentrations of potentially exploitable nutrients. Aiming to develop new sustainable solutions, this study explored the synergistic application of enzymatic treatment and sourdough fermentation to re-cycle industrial bread by-products for new sourdough bread making. Lactiplantibacillus plantarum SD69.B2 and Saccharomyces cerevisiae SD69.E3 were used as starters, while α-amylase, amyloglucosidase and protease were assessed for their ability to hydrolyze starch and proteins, providing more available carbon and nitrogen sources for the microorganisms. The bread waste-based sourdoughs made by combining protease and L. plantarum SD69.B2 alone or in combination with S. cerevisiae SD69.E3 were selected based on acidification and growth kinetics, and their biochemical, amino acid, and peptide profiles were also characterized demonstrating promising properties. Therefore, they were used, at different percentages, for bread making. Although a slightly acidic pH and a low leavening power, due to the denatured proteins and gelatinized starch in the bread by-products, the texture and sensory analyses of new breads revealed better textural attributes, smell, acidic taste, and overall acceptability compared to the control. The possible reasons behind such features were discussed. The overall results demonstrated that the approach proposed in this study was effective to valorize bread by-products, and it represents a starting point to develop strategies responding to the current perspective of circular economy in food industry.

From waste management to circular economy: Leveraging thermophiles for sustainable growth and global resource optimization

Waste of any origin is one of the most serious global and man-made concerns of our day. It causes climate change, environmental degradation, and human health problems. Proper waste management practices, including waste reduction, safe handling, and appropriate treatment, are essential to mitigate these consequences. It is thus essential to implement effective waste management strategies that reduce waste at the source, promote recycling and reuse, and safely dispose of waste. Transitioning to a circular economy with policies involving governments, industries, and individuals is essential for sustainable growth and waste management. The review focuses on diverse kinds of environmental waste sources around the world, such as residential, industrial, commercial, municipal services, electronic wastes, wastewater sewerage, and agricultural wastes, and their challenges in efficiently valorizing them into useful products. It highlights the need for rational waste management, circularity, and sustainable growth, and the potential of a circular economy to address these challenges. The article has explored the role of thermophilic microbes in the bioremediation of waste. Thermophiles known for their thermostability and thermostable enzymes, have emerged to have diverse applications in biotechnology and various industrial processes. Several approaches have been explored to unlock the potential of thermophiles in achieving the objective of establishing a zero-carbon sustainable bio-economy and minimizing waste generation. Various thermophiles have demonstrated substantial potential in addressing different waste challenges. The review findings affirm that thermophilic microbes have emerged as pivotal and indispensable candidates for harnessing and valorizing a range of environmental wastes into valuable products, thereby fostering the bio-circular economy.

Life cycle assessment of fermentative production of lactic acid from bread waste based on process modelling using pinch technology

Bread waste (BW), a rich source of fermentable carbohydrates, has the potential to be a sustainable feedstock for the production of lactic acid (LA). In our previous work, the LA concentration of 155.4 g/L was achieved from BW via enzymatic hydrolysis, which was followed by a techno-economic analysis of the bioprocess. This work evaluates the relative environmental performance of two scenarios - neutral and low pH fermentation processes for polymer-grade LA production from BW using a cradle-to-gate life cycle assessment (LCA). The LCA was based on an industrial-scale biorefinery process handling 100 metric tons BW per day modelled using Aspen Plus. The LCA results depicted that wastewater from anaerobic digestion (AD) (42.3-51 %) and cooling water utility (34.6-39.5 %), majorly from esterification, were the critical environmental hotspots for LA production. Low pH fermentation yielded the best results compared to neutral pH fermentation, with 11.4-11.5 % reduction in the overall environmental footprint. Moreover, process integration by pinch technology, which enhanced thermal efficiency and heat recovery within the process, led to a further reduction in the impacts by 7.2-7.34 %. Scenario and sensitivity analyses depicted that substituting ultrapure water with completely softened water and sustainable management of AD wastewater could further improve the environmental performance of the processes.

High Production of Maltooligosaccharides in the Starch Liquefaction Process: A Study on the Hyperthermophilic Mechanism of α-Amylase

The efficient production of high-value-added bioproducts from starchy substances requires α-amylases with hyperthermophilic properties for industrial starch liquefaction. In this study, two hyperthermophilic α-amylases with significant differences in thermostability, PfAmy and TeAmy, were comparatively studied through structural analysis, domain swapping, and site-directed mutagenesis, finding that three residues, His152, Cys166, and His168, located in domain B were the main contributors to hyperthermostability. The effects of these three residues were strongly synergistic, causing the optimum temperature for the mutant K152H/A166C/E168H of TeAmy to shift to 95-100 °C and stabilize at 90 °C without Ca²⁺. Compared to PfAmy and TeAmy, the mutant K152H/A166C/E168H, respectively, exhibited 1.7- and 2.5-times higher starch hydrolysis activity at 105 °C and pH 5.5 (10411 ± 70 U/mg) and released 1.1- and 1.7-times more maltooligosaccharides from 1% starch. This work has interpreted the hyperthermophilic mechanism of α-amylase and thereby providing a potential candidate for the efficient industrial conversion of starch to bioproducts.