Sourdough Technology-A Traditional Way for Wholesome Foods: A Review

Technological Performance and Selection of Lactic Acid Bacteria Isolated from Argentinian Grains as Starters for Wheat Sourdough

The selection of lactic acid bacteria strains is interesting for the development of sourdough to obtain wheat bread with improved technological and nutritional properties. In this work, the performance of ten different LAB strains isolated from diverse cereals in wheat sourdough was evaluated. Five facultative heterofermentative (Lactobacillus pentosus ES124, Lactobacillus paralimentarius ES259, Lactobacillus plantarum ES137, Lactobacillus plantarum ATCC8014 and Lactobacillus plantarum ES147), three obligately heterofermentative (Lactobacillus brevis ES253, Lactobacillus fermentum ES142 and Lactobacillus fermentum ES148) and two homofermentative (Pediococcus acidilactici ES22 and Enterococcus faecium ES74) lactic acid bacteria strains were evaluated in ten single strain fermentations. Sugar profile, volatile compounds and proteolytic ability of sourdoughs were analyzed. The microbiological counts showed that facultative heterofermentative strains presented higher counts than homofermentative sourdoughs. Monosaccharides (glucose and fructose), maltose and sucrose, isomaltose and dextrin were detected in fermentations with homofermentative strains whilst in those with heterofermentative strains maltose/sucrose, isomaltose and dextrin were found. L. paralimentarius ES259 and L. pentosus ES124 showed the highest diversity of volatile compounds. L. plantarum ES137 and P. acidilactici ES22 were the strains with the highest proteolytic activity. The technological performance allowed us to select LAB as starters to develop breads with specific rheological properties and final quality.

Effects of different starter cultures on the quality characteristics and shelf-life of fermented rice cake

The effects of Makgeolli, dry yeast (DY), sourdough with dry yeast (SDDY) and sourdough with Makgeolli (SDMG) on the quality of fermented rice cakes (FRCs) stored at 23 °C for 3 days were determined. The acidity of SDDY and SDMG significantly increased with increasing fermentation time. The FRCs supplemented with sourdough had slightly higher moisture contents than others. The addition of DY and SDDY increased the specific volume of the FRC, in which its texture was softer. The addition of DY and sourdoughs significantly decreased the firming rate of crumb and improved the sensory qualities. The sourdoughs retarded amylopectin retrogradation, indicating their anti-staling effect on the FRC. Compared to the control, the shelf-lives of FRCs made with DY and SDDY were extended by 0.7 and 0.5 days based on the instrumental hardness, respectively. DY and SDDY effectively improved the appearance and texture of FRC and extended its shelf-life.

Impact of aging on the overall liking and sensory characteristics of sourdough breads and comparison of two methods to determine their sensory shelf life

The objectives of the present work were to study the evolution of the sensory properties and overall liking of four sourdough breads over their lifespans and to determine their sensory shelf life (SSL). We also intended to identify the main sensory characteristics leading to a decrease in overall liking and the end of the consumption of the breads. Seventy-eight consumers evaluated different 1 kg sourdough breads at home. Two methods were used to describe the evolution of the sensory properties and overall liking: one based on ratings of descriptors' intensities and the other based on the magnitude of the changes observed since the previous consumption. As expected, the results showed that sensory properties and liking scores evolved over time. While the aroma and taste properties changed little, the texture deteriorated significantly. The overall liking scores decreased steadily over time, while the percentage of subjects who stopped eating bread increased. "Easiness to cut with the teeth," "easiness to chew," "crispness," and "softness" were the main characteristics positively correlated with the overall liking scores and negatively correlated with the percentage of rejection. In contrast, "dryness of the crumb" was negatively correlated with the liking scores and positively correlated with the percentage of rejection. A survival analysis determined that the SSL (50% rejection) of the breads was approximately 2.5 days. Interestingly, we highlighted that the average liking score corresponding to the SSL was just below the middle of the overall liking scale. PRACTICAL APPLICATION: The results of this work could be of interest to bread-making professionals who will be able to use the main conclusions to advise their clients and possibly adapt the bread format to their sensory shelf life. This work was also an opportunity to highlight sourdough bread, which offers more flexibility than French baguette in managing the consumption of the bread purchased. The alternative approach tested to measure the evolution of sensory characteristics and overall liking could interest the professionals of sensory analysis.

Effects of sourdough on improving the textural characteristics of microwave-steamed cake: A perspective from dielectric properties and water distribution

A sourdough combined with microwave heating method was adopted to make steamed cake (SSC), the dough yield, fermentation time and additive amount of sourdough were optimized by Response Surface Methodology (RSM) to obtain microwave-steamed cake (MSSC) with high-quality attributes and then the potential mechanism of sourdough on the improvement of the MSSC texture was investigated. The addition of sourdough with the optimized parameters could greatly improve the specific volume, porosity, hardness, and chewiness of MSSC, which was mainly related to changes in dielectric properties and water distribution. The results of dielectric properties confirmed that sourdough increased the dielectric properties of the system during microwave heating, affecting the microwave heating characteristics. And the changes of water states and distribution by T₂ relaxation analysis showed that sourdough restricted water mobility during heating and facilitated the retention of water trapped in MSSC. Additionally, the scanning electron microscopy (SEM) images indicated that sourdough weakened the gluten network structure, and triggered a looser and smoother microstructure. PRACTICAL APPLICATION: Steamed cake (SSC) is one of the most popular fermented foods in China, while its commercial development is greatly limited by the drawbacks of traditional steam heating. In recent years, the applications of microwave heating and sourdough in cereal-based foods processing have gained more and more interest. However, there is little information about the application of sourdough combined with microwave heating in SSC production. This study revealed that sourdough addition increased the specific volume, porosity, texture, and consumer preference of MSSC, providing a natural, high-efficiency, and easy-to-operate means for the fabrication of high-quality fermented foods.

Isolation of Exopolysaccharide-Producing Yeast and Lactic Acid Bacteria from Quinoa (Chenopodium Quinoa) Sourdough Fermentation

Quinoa, a nutritional grain, can be used as an ingredient in gluten-free sourdoughs. This study characterizes quinoa flour spontaneous fermentation with emphasis in the isolation of exopolysaccharide (EPS) producer bacteria. Real, red and black grains were studied. Dough yield, microbiota composition and fermentation biochemistry were determined for a total of 36 quinoa flour fermentations. The fermentation biochemistry was monitored by high-performance liquid chromatography (HPLC) analysis, pH measurement and titratable acidity. Changes in the microbiota were monitored by plating on deMann Rogosa and Sharp 5 agar (MRS5) and yeast and mold agar (YMA) plates and with metagenetic analysis. The ability to produce exopolysaccharides was screened in selected lactic acid bacteria (LAB) isolates. Production of organic acids in the spontaneous fermentation dropped the pH to 4.0 ± 0.3. The community of presumptive LAB reached 8.37 ± 0.01 log colony forming units (CFU)/mL by day 8 of back-slopped fermentations. The microbiota was composed of Lactobacillus, Enterococcus, Leuconostoc, Lactococcus, Pediococcus and Weissella. P. pentosaceous,L. citreum and W. cibaria were able to produce EPS in a starch-rich medium. P. pentosaceous showed higher exopolysaccharide yield, rapid acidifying kinetics and was able to drop the dough broth pH to values below 4.0 and a positive fermentation quotient after 24 h of incubation. Therefore, the bacterium might be a potential candidate for quinoa sourdough production.

Diversity of bacterial communities in traditional sourdough derived from three terrain conditions (mountain, plain and basin) in Henan Province, China

To elucidate the bacterial community composition of sourdoughs from different terrain conditions, thirty-two Chinese traditional sourdough samples were collected from three terrain conditions (mountain, plain and basin) in Henan Province. High-throughput sequencing and culture-dependent approaches were employed to identify the bacterial diversity of the sourdough samples. A total of two hundred and six isolates were characterized via 16S rRNA gene sequencing. Pediococcus pentosaceus was isolated from every sample and was the predominant species in the sourdough samples, accounting for 58% of the relative abundance. High-throughput sequencing revealed that the predominant genera (mainly Pediococcus) in the basin group were significantly different from those in the mountain and plain groups. The genus Lactobacillus was predominant in the plain and mountain sourdough samples. Pediococcus pentosaceus was the absolute dominant strain in the basin sourdough samples. Acetobacter, which was widely distributed only in mountain samples, was recognized as the representative genus of the mountain samples. Moreover, we first reported Gluconobacter oxydans in sourdough. This study provided insight into the bacterial diversity of sourdough from three terrain conditions (mountain, plain and basin) in Henan Province and could serve as a reference for the isolation of desired bacterial strains.

Flaxseed Cake as a Tool for the Improvement of Nutraceutical and Sensorial Features of Sourdough Bread

Flaxseed has been recently studied for the formulation of healthy functional foods that are also useful for the prevention of chronic diseases. In this context, the production of sourdough bread fortified with different percentages of flaxseed cake was performed and the interactions among the bioactive compounds derived from both sourdough and flaxseed cake were investigated. The organoleptic properties as well as nutraceutical and chemical characteristics regarding pH, ethanol, lactic and acetic acid content, fatty acids profile, the concentration of total polyphenols, antioxidant capacity, and aroma volatile organic compounds were determined to evaluate the efficacy of leavening in the different matrices in comparison with the traditional bread. The results obtained demonstrated that flaxseed cake-enriched sourdough bread can represent a potential vehicle for bioactive compounds with the possibility of obtaining high-quality products with improved nutritional profiles and desired health attributes. Furthermore, the bread obtained with the addition of 7.5% of flaxseed cake was individuated as the best formulation to produce sourdough bread fortified with flaxseed cake by the overlap between three series of information coming from physical-chemical, nutritional, and sensorial analyses. In conclusion, in the operating conditions adopted, the use of flaxseed cake could represent a viable alternative for the production of fortified bread based on sourdough technology.

From Microbial Ecology to Innovative Applications in Food Quality Improvements: the Case of Sourdough as a Model Matrix

Since millennia, humankind has exploited microbial diversity associated to give food matrices in order to obtain fermented foods and beverages, resulting in products with improved quality and extended shelf life. This topic has received deserved and continuous interest in the scientific community, for the reason of its significance as a driver of innovation in the food and beverage sector. In this review paper, using sourdough as a model matrix, we provide some insights into the field, testifying the relevance as a transdisciplinary subject. Firstly, we encompassed the prokaryotic and eukaryotic microbial diversity associated with the sourdough ecosystems. The importance of this micro-biodiversity in the light of flour-related chemical diversity was examined. Finally, we highlighted the increasing interest in microbial-based applications oriented toward biocontrol solution in the field of sourdough-based products (i.e., bread).

Development of new microalgae-based sourdough "crostini": functional effects of Arthrospira platensis (spirulina) addition

The aim of this work was to evaluate the influence of Arthrospira platensis F&M-C256 (spirulina) incorporation on the nutritional and functional properties of "crostini", a leavened bakery product largely consumed in Italy and Europe. Sourdough was used as leavening and fermentation agent and three concentrations of A. platensis F&M-C256 were tested: 2%, 6% and 10% (w/w). Despite a lower volume increase compared to the control, the A. platensis F&M-C256 "crostini" doughs reached a technological appropriate volume after fermentation. At the end of fermentation, no significant differences in microorganisms concentrations were observed. A. platensis F&M-C256 "crostini" showed higher protein content compared to the control. Considering the European Commission Regulation on nutritional claims, "crostini" incorporated with 6% and 10% biomass can be claimed to be a "source of protein". Six and ten percent A. platensis "crostini" also presented significantly higher antioxidant capacity and phenolics. A significantly lower value of in vitro dry matter and protein digestibility between A. platensis F&M-C256 "crostini" and the control was found. The overall acceptability decreased with increasing A. platensis F&M-C256 addition. The combination of spirulina biomass addition and the sourdough technology led to the development of a novel microalgae-based bakery product with nutritional and functional features.

FEATURES OF DETERMINING THE QUALITY OF ETHNIC SOURDOUGHS AND WAYS OF USING THEM IN BAKING AND CATERING BUSINESS

The usage of various sourdoughs increases in order to expand the range and improve the quality, nutritional properties, and safety of bread products. Spontaneous sourdoughs with different formulas and preparation parameters are used in technologies of popular ethnic products. This paper is devoted to the study of wheat spontaneous sourdoughs, such as hop, pea-anise, and wine yeast sourdough. The effect of the grade and baking properties of flour, the inclusion of additional ingredients that can act as enrichers of the nutrient medium, carriers of additional fermentation microorganisms, as well as controllers of the species composition of the microflora, on their quality has been studied. The basic scheme of preparing spontaneous wheat sourdough is developed; the basic stages and parameters of the dilution and production cycles are noted. The methods of controlling the process and quality of sourdough are described, the recommended values of the lifting force and titrated acidity are presented, as well as sensory characteristics. It has been established, that the required fermentation ability and acid accumulation rate of sourdough are obtained in different time: 24 hours for wine yeast sourdough, 7–8 days for hop sourdough, and up to 15 days of a dilution cycle for pea-anise sourdough. The stabilizing effect of active substances of hop and anise on the quality of sourdough has been proven. Hop and pea-anise sourdough retain the necessary biotechnological properties for 90 days of propagation, but wine yeast sourdough loses its quality after 30 days, sourdough without additives loses it after 9 days. The results of the research have theoretical and practical use, since the proposed scheme and approaches to developing the wheat sourdough technology and controlling their quality can be used to study various ethnic sourdoughs and technology of bread based on them. The experimental data on the quality of selected sourdoughs can be used to develop the technology of bread products with improved quality, nutritional value, and safety, ethnic products, and products "made according to old technologies".

Use of Selected Lactobacilli to Increase γ-Aminobutyric Acid (GABA) Content in Sourdough Bread Enriched with Amaranth Flour

γ-Aminobutyric acid (GABA) is the primary inhibitory neurotransmitter of the central nervous system and possesses various physiological functions. GABA production can be obtained thanks to lactic acid bacteria activity in different foods such as sourdoughs. Recently, breads made from blends of pseudocereals and wheat flours have attracted much attention. Amaranth is especially interesting because of its high nutritional value, having a high protein content and containing different antioxidant compounds. Therefore, this study aimed to obtain sourdough breads enriched with GABA thanks to bacterial activity and to investigate the effect of amaranth flour addition on the antioxidant and sensorial properties of bread. Eighteen lactobacilli strains were assayed for GABA production in amaranth and wheat flour liquid sourdoughs. Two strains, Lactobacillus brevis A7 and Lactobacillus farciminis A11, demonstrated high GABA producing capability; hence, they were used to prepare breads containing 20% amaranth flour. The results confirmed the capability of the two strains to increase GABA concentrations (up to 39 mg/kg) in breads. Samples with amaranth addition showed a significantly higher total phenolic content compared to the control bread (more than 15 mg GAE 100 g^-1 dwb); sensory analysis showed that breads with amaranth were moderately acceptable. Nevertheless, their general liking evaluation was significantly lower compared to the control bread. The addition of pseudocereal to traditional wheat sourdough and selection of lactobacilli allowed the production of baked goods with enhanced GABA content and antioxidant capacity, but recipes have to be developed to increase the organoleptic acceptability of the final products.

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.

Assessment of Ready-to-Use Freeze-dried Immobilized Biocatalysts as Innovative Starter Cultures in Sourdough Bread Making

In the present study the effect of innovative biocatalysts as starter cultures in sourdough bread making was explored. The biocatalysts consisted of Lactobacillus paracasei K5 and Lactobacillus bulgaricus ATCC 11842 (in single and mixed form), immobilized on delignified wheat bran (DWB), and freeze dried without cryoprotectants. The parameters monitored were physicochemical characteristics, mold and rope spoilage appearance, volatile composition, and organoleptic characteristics. Results obtained showed that both biocatalysts exhibit good fermentative activity. However, the best results were achieved when freeze-dried immobilized L. paracasei K5 was applied as a single culture. In particular, the produced bread had a higher acidity (8.67 mL 0.1 N NaOH) and higher organic load (2.90 g/kg lactic acid and 1.11 g/kg acetic acid). This outcome was the main reason why this bread was preserved more regarding mold spoilage (14 days) and rope spoilage (12 days), respectively. In addition, the employment of freeze-dried immobilized L. paracasei K5 led to bread with better aromatic profile in terms of concentrations and number of volatile compounds produced as gas chromatography/mass spectrometry (GC/MS) analysis proved. Finally, no significant differences were observed through sensorial tests. Last but not least, it should be highlighted that the used microorganisms were cultured in cheese whey, minimizing the cost of the proposed biotechnological procedure.

Production, Utilization and Nutritional benefits of Orange Fleshed Sweetpotato (OFSP) Puree Bread: A Review

Bread though an exotic food product in sub-Saharan Africa, has been an important cereal product consumed by most individuals among the vast Sub-Saharan African population. Bread formulations in both the local and industrial production have evolved. The latest and emerging technology in bread formulation involve the incorporation of orange-fleshed sweetpotato (OFSP) puree. OFSP puree-based bread is commercially available across sub-Saharan Africa (SSA) and is being promoted due to the potential nutritional benefits that it possesses. Together with OFSP flour based bread, OFSP puree based bread serves as a good food vehicle for β-carotene; this serves to alleviate vitamin A deficiency (VAD) especially among the vulnerable population in SSA. The production of OFSP puree based bread has so far been relying on fresh OFSP puree or cold-chain stored OFSP puree. However, this has presented economic challenges and problems to the sustainability and expansion in OFSP puree bread production. Cold chain stored OFSP puree is capital intensive and has inconsistent supply. With the development of shelf-storable preservative treated OFSP puree, most of these challenges will be overcome without undoing the currently harnessed benefits. The use of OFSP puree in bread baking can then be expanded easily at minimal production costs and maximum retention of nutritional quality. Therefore, the use of the shelf-storable OFSP puree in bread baking needs to be evaluated further to present a substantiated case for its use. The current review has been developed with focus on the scientific advances in the production of OFSP puree based bread from both historical and a forecast perspective. The scientific progress and breakthroughs in the use of OFSP puree in bread are critically reviewed.

Microbial characterization of five Chinese traditional sourdoughs by high-throughput sequencing and their impact on the quality of potato steamed bread

To improve the quality of potato steamed bread, the microbial diversity of 5 different sourdoughs and their effects on potato steamed bread were studied. The proximate composition analysis differentiated the Chinese traditional sourdough (CTS) with different levels of nutrients and pH (3.82-6.22). High-throughput sequencing revealed the predominant microbes in the five CTSs were Lactobacillus, Pediococcus, and Wickerhamomyces. Similarities of bacterial and fungal compositions were observed within them. The fermentation rheological results suggested CTS1 and CTS3 had higher total gas production value (2355.5 mL and 2249.5 mL respectively) than baker's yeast. CTSs resulted in various effects on the appearance and texture properties of potato steamed bread with CTS1 showed the highest specific volume (2.38 mL/g) and sensory score (7.43). Wickerhamomyces significantly correlated with the total gas production, hardness, resilience, and lightness of potato steamed bread. The study suggested a potential application of CTSs in fermented potato staple foods.

Effects of Sourdough on FODMAPs in Bread and Potential Outcomes on Irritable Bowel Syndrome Patients and Healthy Subjects

Background: Fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs) are an heterogeneous group of compounds that can be poorly digested and may have a range of effects on gastrointestinal processes. FODMAPs are found in a wide variety of foods, including bread. FODMAPs’ intake is associated with the onset of symptoms of irritable bowel syndrome (IBS). On the other hand, some FODMAPs contribute to the healthy maintenance of intestinal microbiota. Volume increase of bread dough commonly relies on the use of two biological leavening agents, sourdough and baker’s yeast and, in some cases, a combination of both.

Scope and Approach: The main objective of this review is to discuss the association between FODMAPs and IBS, beneficial effects of FODMAPs on healthy subjects and potential impact of biological leavening agents on FODMAPs content of bread.

Key Findings and Conclusion: Given that yeasts and lactic acid bacteria, the dominant microorganisms in sourdough, may degrade FODMAPs, it would be possible to modulate the FODMAPs concentration in bread, thus positively affecting consumers’ health.

Performances of Different Metabolic Lactobacillus Groups During the Fermentation of Pizza Doughs Processed from Semolina

The main hypothesis of this work is that facultative and obligate heterofermentative Lactobacillus species can differently impact the final characteristics of pizza. The objective was to evaluate separately the behaviors of the obligate heterofermentative species (OHS), such as Lactobacillus sanfranciscensis, Lactobacillus brevis, and Lactobacillus rossiae, and the facultative heterofermentative species (FHS), including Lactobacillus plantarum, and Lactobacillus curvatus, in the sourdoughs to be used for pizza production. The production of the experimental pizzas was carried out with semolina (Triticum turgidum L. ssp. durum). The acidification process—which was followed by pH, total titratable acidity (TTA), and lactic acid bacteria (LAB) development—indicated for all of the experimental trials that the kinetics is comparable to those of the controls. The fermentation quotient of the FHS trial was particularly higher than that of the other trials, including the control production performed with a sourdough inoculum used in an artisanal bakery. The dominance of the added strains indicated the clear persistence of L. sanfranciscensis PON100336, L. brevis 200571, and L. plantarum PON100148 in the obligate–facultative heterofermentative species (OFHS) trial. The pizzas were baked without seasoning in order to investigate weight loss, color, morphology, and a generation of volatile organic compounds (VOCs). The data showed the differences among trials regarding the inocula. Eight classes of VOCs were detected in the pizza samples with aldehydes, esters, alcohols, and acids as major compounds. The sensory attributes were significantly different for the judges and the pizzas. The multivariate statistical approach found marked differences among the trials. The results indicated that the application of mixed cultures of the facultative heterofermentative species of Lactobacillus determined high quality pizzas.

Postprandial Gastrointestinal Function Differs after Acute Administration of Sourdough Compared with Brewer's Yeast Bakery Products in Healthy Adults

Background

Europeans consume large quantities of bakery products, although these are known as one of the food categories that potentially leads to postprandial symptoms (such as fullness and bloating).

Objective

The aim of this study was to evaluate the effects of sourdough baked goods on gastric emptying and gastrointestinal fermentation and symptoms in healthy people.

Methods

In a double-blind, randomized crossover study, 2 sourdough croissants (SCs) or 2 brewer's yeast croissants (BCs) were served as single meals to 17 healthy adults [9 women; age range: 18-40 y; body mass index range (in kg/m2): 18-24]. Gastric volume (GV) was evaluated by magnetic resonance to calculate gastric-emptying rate in the 3-h interval after croissant ingestion. A hydrogen breath test was performed to measure hydrogen production after SC and BC ingestion. Palatability and postprandial gastrointestinal symptoms (discomfort, nausea, fullness, and bloating) over a 4-h period after the meal were evaluated. The area under the curve (AUC) was used to evaluate the overall effects on all variables tested.

Results

The total GV AUC was reduced by 11% during the 3 h after the consumption of SCs compared with BCs (P = 0.02). Hydrogen production during the 4-h interval after ingestion of SCs was 30% lower than after BCs (P = 0.03). SCs were rated as being >2 times as palatable as BCs (P < 0.001). The overall severity of postprandial symptoms was 36% lower during the 4 h after intake of SCs compared with BCs (P = 0.05).

Conclusion

Sourdough bakery products could promote better postprandial gastrointestinal function in healthy adults and be more acceptable than those prepared with brewer's yeast. This trial was registered at www.clinicaltrials.gov as NCT03207516.

Pilot Study: Comparison of Sourdough Wheat Bread and Yeast-Fermented Wheat Bread in Individuals with Wheat Sensitivity and Irritable Bowel Syndrome

Many patients suspect wheat as being a major trigger of their irritable bowel syndrome (IBS) symptoms. Our aim was to evaluate whether sourdough wheat bread baked without baking improvers and using a long dough fermentation time (>12 h), would result in lower quantities of alpha-amylase/trypsin inhibitors (ATIs) and Fermentable, Oligo-, Di-, Mono-saccharides and Polyols (FODMAPs), and would be better tolerated than yeast-fermented wheat bread for subjects with IBS who have a poor subjective tolerance to wheat. The study was conducted as a randomised double-blind controlled 7-day study (n = 26). Tetrameric ATI structures were unravelled in both breads vs. baking flour, but the overall reduction in ATIs to their monomeric form was higher in the sourdough bread group. Sourdough bread was also lower in FODMAPs. However, no significant differences in gastrointestinal symptoms and markers of low-grade inflammation were found between the study breads. There were significantly more feelings of tiredness, joint symptoms, and decreased alertness when the participants ate the sourdough bread (p ≤ 0.03), but these results should be interpreted with caution. Our novel finding was that sourdough baking reduces the quantities of both ATIs and FODMAPs found in wheat. Nonetheless, the sourdough bread was not tolerated better than the yeast-fermented bread.

Genotyping of Lactobacillus sanfranciscensis isolates from Chinese traditional sourdoughs by multilocus sequence typing and multiplex RAPD-PCR

Lactobacillus sanfranciscensis is the predominant lactic acid bacteria (LAB) species in Chinese traditional sourdoughs and conduces to the flavor and rheology properties of Chinese steamed bread, a staple food originated in China over 1500years ago. The aim of this study is to describe the intraspecific diversity of 98 L. sanfranciscensis isolates from 11 Chinese traditional sourdoughs in different regions by multilocus sequence typing (MLST) and multiplex random amplified polymorphic DNA-polymerase chain reaction (multiplex RAPD-PCR). MLST scheme was reduced from six gene fragments (gdh, gyrA, mapA, nox, pgmA and pta) to five (gdh, gyrA, mapA, nox and pta) since the fragment of pgmA displayed only one allele. 10 different sequence types (STs) were revealed by MLST and 6 of them containing 79.8% of the isolates were classified into one clonal complex, demonstrating a close relationship among them. The multiplex-RAPD analysis was performed by employing the combined primers OPL-05+RD1 and divided the 98 L. sanfranciscensis isolates into 6 types with the similarity level of 70%. According to the result, it seems that the genotypic variations of L. sanfranciscensis strains showed by MLST have no relations to geographical origin. MLST seems to have a higher discriminatory power compared with multiplex-RAPD since it produced more groups, but multiplex-RAPD could help to distinguish some strains in the same ST. Hence, an optimal genotypic characterization of L. sanfranciscensis was obtained under the combination of MLST and multiplex-RAPD analysis, targeting different genetic variations.

Application of Tunable Diode Laser Spectroscopy for the Assessment of Food Quality

Adequate food packaging is important to ensure food quality and prolong the shelf life of food. Frequently, the method of modified atmosphere packaging (MAP) is used. We used a tunable diode laser spectroscopy technique to detect the oxygen content in food packages, e.g., in packaged milk and bread. Different detection geometries were adopted to be able to collect scattering light that had passed through the gas volume in the packages, and to avoid the disturbance of ambient air. Furthermore, studies of the bread-baking process have been performed by measuring the water vapor signals in a fermenting dough. The results demonstrate that the technique has a great potential for nonintrusive assessment of food quality and the bread-baking process.

Processing- and product-related causes for food waste and implications for the food supply chain

Reducing food waste is one of the prominent goals in the current research, which has also been set by the United Nations to achieve a more sustainable world by 2030. Given that previous studies mainly examined causes for food waste generation related to consumers, e.g., expectations regarding quality or uncertainties about edibility, this review aims at providing an overview on losses in the food industry, as well as on natural mechanisms by which impeccable food items are converted into an undesired state. For this, scientific literature was reviewed based on a keyword search, and information not covered was gathered by conducting expert interviews with representatives from 13 German food processing companies. From the available literature, three main areas of food waste generation were identified and discussed: product deterioration and spoilage during logistical operations, by-products from food processing, and consumer perception of quality and safety. In addition, expert interviews revealed causes for food waste in the processing sector, which were categorised as follows: losses resulting from processing operations and quality assurance, and products not fulfilling quality demands from trade. The interviewees explained a number of strategies to minimise food losses, starting with alternative tradeways for second choice items, and ending with emergency power supplies to compensate for power blackouts. It became clear that the concepts are not universally applicable for each company, but the overview provided in the present study may support researchers in finding appropriate solutions for individual cases.