Development of processes for the production of postbiotic functional foods

Several techniques were developed in order to enhance the content of bioactive compounds or promote their production in food products. Lactic acid fermentation is one of the most important food processing technologies used to produce functional probiotic foods. A novel category of fermented functional foods is gaining increasing interest and is represented by postbiotic products, consisting of inactivated microorganisms and molecules (enzymes, peptides, organic acids) produced in the final or intermediate stage of the metabolic process of these probiotic bacteria. Although postbiotics do not contain live microorganisms, they show a beneficial health effect through similar mechanisms that are characteristic of probiotics, minimizing the risks associated with their intake. For this reason, they could be considered a safer alternative to clinical application for immune-deficient patients or infants. This research, in collaboration with Kraft Heinz Company, consisted of the development of processes for the production of wet and dried functional foods with a postbiotic effect, intended for categories of people with high pathological vulnerability, such as children, elderly people and pregnant women. The purpose of this project was to investigate the effect of fermentation process, carried out using Lactobacillus paracasei CBA L74, patented by Kraft Heinz, heat treatments and drying processes on the postbiotic properties of the semi-finished products obtained, choosing as raw materials milk, rice flour and leguminous (beans) suspensions. The processes were examined and optimized at laboratory scale and then implemented at pilot scale with a successful and efficient scaling up, except for beans that had been an unexplored food matrix to be fermented until then and required a further optimization of protocols at laboratory scale before performing the trials on the pilot plant. At lab scale, rice and milk fermentation were carried out with and without pH control and in both cases an improvement in the terms of kinetic performance of the process was observed when pH control was implemented. The fermentation process was characterized in terms of bacterial growth (maximum values of 1.9 × 10^8 ± 1.2 × 10^8 CFU/mL after 20 h and 5.3 × 10^8 ± 4.7 × 10^8 CFU/mL after 18 h were achieved for milk and rice flour fermentations, respectively), lactic acid concentration (maximum values of 1.2 ± 0.3 g/L and 4.4 ± 0.21 g/L were achieved after 24 h of fermentation process for milk and rice flour, respectively) and production of a selected functional metabolite, considered as responsible of the immunomodulatory activity of the postbiotics obtained (6.93 ± 0.5 mg/L and 17.23 ± 0.28 mg/L after 24 h of fermentation, for milk and rice flour,respectively). An aqueous suspension of cooked beans was fermented without pH control in two different mixing conditions. The mixing system was improved by designing an impeller that guarantees a higher homogeneity of the medium inside the reactor: the results showed better performances in terms of growth rate and lactic acid production, reaching a microbial charge of approximately 1 × 10^9 CFU/mL after 14 h and a lactic acid content of 2 g/L after 16 h of process. The functional peptide was not detected in the fermenting bean suspension, so a further optimization of the protocol will be necessary for this purpose. A thermal treatment at 90°C for 1 min, for rice and milk, and at 90°C for 15 min, for beans, was sufficient to reduce the bacterial charge in the fermented product without negatively affecting the products quality; freeze drying and spray drying technologies had the same impact on the food products, not altering their organoleptic and chemical properties: a promising result since spray drying technology is usually used at larger scale. The results obtained at pilot scale for milk and rice flour were completely overlapped. During milk fermentation, a maximum bacterial load of 6.7 × 10^8 ± 2.65 × 10^8 CFU/mL was reached after 20 h of process; a lactic acid content of 2.1 ± 0.25 g/L and a peptide concentration of 14.20 ± 0.80 mg/L were observed at the end of fermentation. As for rice flour, a maximum bacterial growth of 1.27 × 10^9 ± 6.9 × 10^8 after 18 h of process, a maximum lactic acid production of 6.03 ± 0.7 g/L after 24 h and a maximum functional peptide content of 22.60 ± 4.10 mg/L after 20 h of fermentation were obtained. For both scales, rice flour fermentation gave better results in terms of bacterial growth, lactic acid and functional peptide production, probably for the rice prebiotic components. Also, at pilot scale, a thermal treatment of 90°C for 1 min was sufficient to reduce the bacterial charge in the fermented products and it was confirmed that spray drying technology had a low impact on the product. Moreover, a shelf-life analysis of the products obtained at pilot scale was performed at three different storage temperatures (4°C, 20°C and 37°C) for six months to evaluate the food product stability over time: dried fermented rice resulted more stable than milk

Yeasts, the man’s best friend

1. Introduction In most cultures, bread making depends on a fermentation step. The flour leavening ability was, at first, most probably dependent on spontaneous fermentation. It became a controlled process by the maintenance of fresh innocula from one preparation to the next and this kind of environmental constraints eventually generated a particular type of yeast and bacteria biodiversity, adapted to ferment a certain brand of flour mixture, yielding specific organoleptic characteristics to the dough. Nowadays, although the baking industry generally uses commercially available strains of Saccharomyces cerevisiae for bread making, some types of bread are still prepared using dough carried over from previous makings as a starter. This trend decreased worldwide bread diversity and the cultural values associated, simultaneously increasing the dependence of local producers on world-scale yeast producers. Sustainability demands assessing yeast biodiversity, as well as devising simple and cheap methods for maintaining dough and multiply yeast.Este trabalho é financiado por Fundos FEDER através do Programa Operacional Factores de Competitividade – COMPETE e por Fundos Nacionais através da FCT – Fundação para a Ciência e a Tecnologia no âmbito do projecto PEst-C/BIA/UI4050/201

Recent Advances in the Use of Sourdough Biotechnology in Pasta Making

The growing consumers' request for foods with well-balanced nutritional profile and functional properties promotes research on innovation in pasta making. As a staple food and a common component of diet, pasta can be considered as a vector of dietary fiber, vegetable proteins, vitamins, minerals, and functional compounds. The conventional process for pasta production does not include a fermentation step. However, novel recipes including sourdough-fermented ingredients have been recently proposed, aiming at enhancing the nutritional and functional properties of this product and at enriching commercial offerings with products with new sensorial profiles. The use of sourdough for pasta fortification has been investigated under several aspects, including fortification in vitamin B, the reduction of starch digestibility, and gluten content. Sourdough fermentation has also been successfully applied to non-conventional flours, (e.g., from pseudocereals and legumes), in which an overall increase of the nutritional value and health-promoting compounds, such as a significant decrease of antinutritional factors, were observed. Fermented non-conventional flours, obtained through spontaneous fermentation or using selected starters, have been proposed as pasta ingredients. As the result of wheat replacement, modification in textural properties of pasta may occur. Nonetheless, fermentation represents an efficient tool in improving, besides nutritional and functional profile, the sensory and technological features of fortified pasta.Peer reviewe

Comparison of the antifungal effect of undissociated lactic and acetic acid in sourdough bread and in chemically acidified wheat bread

Sourdough is a very interesting natural preservation system to prolong mould free shelf-life of bread. Numerous studies have reported that the antifungal activity of sourdough is mainly correlated with the presence of lactic (LA) and acetic acid (AA), but very few information is available on the effect of undissociated acid concentrations in the aqueous phase of bread (C-HA; mmole/L). This study was conducted to provide additional information about the mode of action of the acids in sourdough bread, enabling a better shelf-life prediction. This study was divided into two parts. In part 1, three industrial biological sourdoughs were characterized (dough yield, pH, a(w), fermentation quotient, microbiota). During 7 weeks, a shelf-life test with natural flora was conducted with daily checks of visible mould growth (21 degrees C). In part 2, the effect of the acids present in the antifungal active sourdough breads was validated in chemically acidified wheat breads. Complete growth inhibition was observed in full-baked sourdough bread (30 g/100 g dough) containing Lactobacillus sanfranciscensis and Saccharomyces cerevisiae as dominant sourdough micro-organisms, whereas in control bread the shelf-life was limited to 4.4-9.2 days. These full-baked sourdough breads contained 36 mmole undissociated LA/L and 220 mmole undissociated AA/L. The data were used to make General Linear Regression models for shelf-life prediction and resulted in a fit of R-2 = 0.79 when expressing the shelf-life in function of C-HA,C- LA and C-HA,C-AA. In acidified breads, the role of lactic acid was not significant and only impacted shelf-life indirectly through acidification. No difference between antifungal activity of sourdough breads and chemically acidified bread with comparable C-HA,C- AA concentrations was observed. Shelf-life increased when 150-200 mmole undissociated AA/L aqueous phase in bread was present. To conclude, this study showed the importance of the undissociated acid fraction of acetic acid in relation to bread shelf-life, together with bread pH and moisture content

Development of new functional bakery products with health benefits from yoghurt and curd cheese enrichment

Doutoramento em Engenharia Alimentar / Instituto Superior de Agronomia. Universidade de LisboaTogether with the increasing consumer´s awareness about the relation between diet and health, the growing number of individuals with gluten and wheat-related illnesses, such as celiac and irritable bowel diseases, have been the main responsible driver´s for the continued innovation of food companies and the launching of healthy products, including gluten-free version, on the market. Additionally, the strategy of health-food development goes on not only by the usage of nutritional sources but also to the application of alternative processes to meet the consumer’s expectations for natural, clean-label, nutritional and sustainable foods. In those matters, following the current food market trends, the present dissertation was based on the development of new bread formulations, including gluten-free versions, with nutritional and functional added benefits, by the incorporation of nutritional sources, plain yoghurt and curd cheese. The study was extended to the field of sourdough fermentation, combining the yoghurt nutritional properties with the potential of its lactic acid bacteria to be used as a starter in sourdough fermentation. At first approach, the influence of yoghurt and curd cheese (6%-50%) additions to improve the technological, nutritional, and sensory properties of the wheat bread, was studied. Subsequently, the influence of both dairy products (6%-25%) to reduce the wheat bread´s glycemic response, was detailed assessed. Ultimately, the impact of both dairies’ additions (25%) to enhance the wheat bread´s bioactivity, was an important complementary study. At second approach, the protein reinforcement by the incorporation of yoghurt and curd cheese enrichment (5%-20%) to overcome the technological challenge of gluten absence was evaluated, and so that resulted bread would improve nutritional/functional profile. Subsequently, the influence of both dairies (10%-20%) to reduce the glycemic index while improving the bread´s bioactivity, was as well appraised. In the third approach, the usage of plain yoghurt (25%) as a starter in sourdough fermentation aiming for a more functional and easily digestible wheat bread, was studied. Two wheat dough matrices: 1) wheat flour and 2) wheat and whole-grain flour (50% ratio) were considered. Overall, it can be stated that the development of new bread formulations, including gluten-free and sourdough-wheat bread, was successfully achieved, rendering higher nutritional added-value products with health-promoting benefits, that can be linked to a preventive consumer’s diet and include health claims, responding well to the innovation needs of the bakery industryN/

Volatile organic compounds and their generation in sourdough

Received: October 30th, 2022 ; Accepted: April 1st, 2023 ; Published: April 14th, 2023 ; Correspondence: [email protected] technology is involved in bread making process for improving the sensory, rheological, nutritional and shelf life characteristics of bakery products. More than 540 volatile organic compounds (VOCs) and other flavour precursors belonging to the chemical classes, such as aldehydes, ketones, esters, acids, alcohols, terpenes and others, have been identified in sourdoughs and sourdough breads. The synthesis of VOCs is microbial species-specific, originating mainly from fermentation process. VOCs can be used as indicators to characterize microbial processes. Other additional sources of VOCs in sourdoughs are lipid oxidation and browning reactions, the latter of which occurs during the production of dried starter cultures. The purpose of this article is to provide an overview of the composition of VOCs and their effect on the sensory properties of sourdough bread, and to describe the most common extraction methods of VOCs used in the studies of sourdough and bread aroma profile. Long-term propagated sourdough VOCs have been less studied compared to volatiles found in bread crust and crumb or sourdoughs started with defined starter culture(s) due to their complexity and diversity in metabolic pathways, including sophistication of the analytical methodology of VOCs. The relation between sourdough microbiota and its volatile profile is not fully understood and therefore, their variability and precise role as a bread flavour enhancer is not yet known in detail

Effect of Processing on Microbiota Accessible Carbohydrates in Whole Grains

There is potential to increase microbiota accessible carbohydrates (MAC) in whole grains through food processing. Therefore, different processing conditions for boiling and extrusion of whole wheat flour were studied for their effect on MAC. Processing conditions had a minimal effect on fermentation response using 2 fecal samples of disparate composition. However, the processing method had an impact on the fermentation of non-digestible carbohydrates and subsequent short chain fatty acids production, but only for a microbiome with high diversity and a predominance of microbes associated with dietary fiber intake. Subsequently, five processing methods: boiling, extrusion, unleavened bread, yeast bread, and sourdough bread, were studied for their effects on in vitro fermentation of whole wheat flour using the fecal microbiota from 10 subjects. Different grain processing operations caused varying shifts in microbiota composition and activity. Notably, sourdough bread supported a diverse microbial community that produced more butyrate and propionate. Conversely, extrusion led to decreases in diversity and butyrate and propionate production, but enabled increase carbohydrate fermentation. These differences were attributed to changes in the microstructure of the grains. In order to better understand the effects of grain processing on host health, two microbiomes that ranged in diversity and were from subjects who habitually consumed high and low levels of dietary fiber and whole grains, were inoculated into germ free mice. These mice were then fed isocaloric western diets supplemented with cellulose (control), boiled whole wheat, extruded whole wheat, or extruded brown rice. The mice harboring the microbiome from the low dietary fiber consumer had increases in diversity due to whole grains and the whole grain source and processing had differential effects. The mice harboring the microbiome from the high dietary fiber consumer was more diverse and was minimally affected by treatment. These mice had reduced body fat and body weight gain with boiled whole wheat compared to extruded whole wheat while there was no difference between brown rice and whole wheat. Both microbiomes had reduced glucose tolerance with extruded grains. Thus, both the digestion and fermentation are important factors of the effect of whole grains and food processing on host health. Advisor: Devin J. Ros