Effect of Sourdough Bacteria on the Quality and Shelf Life of Bread

ABSTRACT- Considering health and economic issues, today, consumers have become more concerned with foods which contain natural ingredients. Hence, in this study, the effects of plum concentrate and puree which were incorporated into the Taftoon bread formulation at different levels on the rheological, baking properties and shelf life of bread were evaluated. Results showed that addition of plum concentrate and puree improved the quality and shelf life of Taftoon bread. Plum puree was effective in improving dough development time, mixing tolerance index and dough softening while concentrate affected stability and water absorption. Bread containing 4% plums puree had the lowest hardness compared with other samples. Image processing analyses showed that both concentrate and puree improved browning in Taftoon bread. Therefore, plum concentrate and puree can be used as a humectant to improve the quality and shelf life of Taftoon bread.

خواص مکانیکی خمیر نقش مهمی در صنایع پخت ایفا می‌کنند و در مواردی از قبیل تثبیت افزودنی‌ها و مطالعه تاثیر آنها بر سایر خواص خمیر و نان می‌توانند مورد توجه واقع شوند. در این پژوهش، از روش‌های چندمتغیره متقارن (تعیین ضرایب همبستگی و آنالیز مولفه‌های اصلی) و نامتقارن (سطح پاسخ و رگرسیون حداقل مربعات جزئی) به‌منظور مطالعه تاثیر اجزاء ژل بهبوددهنده بر خواص مکانیکی خمیر نان بربری، ارتباط خواص مکانیکی خمیر با سایر خواص خمیر و نان و نیز بهینه‌سازی فرمول ژل استفاده گردید. نمونه‌های ژل بهبوددهنده، محتوی 0 تا g100/g 5/0 سدیم استئاروئیل لاکتیلات، داتم و پروپیلن گلیکول بودند. نتایج نشان داد که با توجه به تغییر مقدار و نوع اجزاء فرمولاسیون ژل، دامنه وسیعی از تغییرات در خواص مکانیکی خمیر ایجاد می‌شود و از اختلاط g100/g 5/0 سدیم استئاروئیل لاکتیلات، g100/g 5/0 داتم و g100/g 5/0 پروپیلن گلیکول بهترین حالت حاصل می‌گردد. ضرایب همبستگی بین خواص مکانیکی خمیر با خصوصیات فارینوگرافی خمیر، کیفیت، جنبه‌های حسی، پردازش تصویر و ماندگاری نان بررسی گردید. همچنین آنالیز مولفه‌های اصلی ثابت نمود که قادر به استخراج اطلاعات مناسبی است و می‌تواند به‌عنوان یک روش آسان برای تحلیل و تفسیر خواص مکانیکی خمیر و ارتباط آنها با سایر خواص خمیر و نان مورد استفاده قرار گیرد. مدل‌های رگرسیونی حداقل مربعات جزئی نیز برای تعیین ارتباط بین خصوصیات مکانیکی خمیر با خصوصیات فارینوگرافی خمیر، خصوصیات کیفی، حسی، پردازش تصویر و ماندگاری نان به‌کار برده شد. نتایج حاصل از آنالیزهای آماری نشان داد که خصوصیات مکانیکی خمیر، قادر به پیشگویی حداقل 50% از خصوصیات خمیر و نان هستند.

PurposeWheat is the staple food in many parts of the world and bread is one of the most important products of wheat flour. There is a need for innovations in bread making to increase its shelf life and consumer's attraction. Fermentation is mostly done by yeast but it does not produce appreciable amounts of organic acids, which are required to enhance the shelf life of bread. The present study aims to determine the effect of bacterial and yeast culture blends on the quality and shelf life of sourdough bread and to observe the sugar utilization during fermentation.Design/methodology/approachThree treatments were made using different blends of bacterial cultures (homo‐fermentative and hetero‐fermentative) and baker's yeast compared with a control having only baker's yeast. Chemical analysis, sugar utilization (Sucrose, glucose and fructose) through high performance liquid chromatography, sensory characteristics (both internal and external) and microbial count (Bacterial and fungal count) for each treatment were conducted at different storage intervals.FindingsThe hetero‐fermentative bacteria i.e. Lactobacillus plantarum along with baker's yeast exhibited the best results regarding the utilization of sugars during fermentation (after 3 h of fermentation 0.0158 mg/ml sugar remained), objective evaluation of bread and its sensory characteristics. The bread prepared using the blend of hetero‐fermentative bacteria (0.5 per cent) and yeast (0.5 per cent) also showed greater resistance against bacteria (9×101 cfu/g after 60 h of storage) and mold (1.1 × 102 cfu/g after 60 h of storage) growth.Research limitations/implicationsHetero‐fermentative bacteria along with baker's yeast can be utilized in sour dough to improve major bread characteristics. This study is a step further in improving the shelf life of sourdough.Originality/valuePresently only baker's yeast is being used by bread industry for fermentation purpose but a blend of bacterial culture along with baker's yeast can give better performance for better quality and shelf life of the bread.

The aim of this work was to study the effects of a novel sourdough system prepared by wheat flour supplemented by combination of pulverized date seed, Lactobacillus plantarum, and/or Lactobacillus brevis as well as Saccharomyces cerevisiae on the sourdough characteristics, quality, sensory, texture, shelf life and image properties of Barbari flat bread. The highest sourdough acidity and bread specific volume was obtained with co-culture of Lb. plantarum+Lb. brevis+S. cerevisiae. The results suggest that fermentation is a potential bioprocessing technology for improving sensory aspects of bread supplemented with pulverized date seed, as a dietary fiber resource. Texture analysis of bread samples during 7days of storage indicated that the presence of pulverized date seed in sourdough was able to diminish bread staling. The interaction of baker's yeast and lactic acid bacteria (LAB) has led to increase the particle average size of bread crumb and decrease the area fraction than the LAB samples. It was observed that all treatments of sourdough Barbari breads had higher cell wall thickness than the control Barbari bread. Avrami non-linear regression equation was chosen as useful mathematical model to properly study bread hardening kinetics. In addition, principal component analysis (PCA) allowed discriminating among sourdough and bread specialties. Partial least squares regression (PLSR) models were applied to determine the relationships between sensory and instrumental data.

The technology of fermented rye bread in Latvia has a strong traditional value. Microorganisms play an important role in the fermentation process of sourdough bread, mainly due to lactic acid bacteria (LAB). Traditional rye bread in Latvia is prepared using scalded flour and sourdough. Total fermentation time can be from 6 till 48 hours, depending on the bakery. Usually sourdough contains two to five LAB species. One of the metabolites in sourdough produced by LAB is exopolysaccharide (EPS). It has been found that 20% of the analysed strains in sourdough are able to produce EPSs from sucrose — mainly fructans and glucans are produced. The exopolysaccha-rides produced by LAB are able to bind water, improving the quality of bread, increasing the volume, delaying staling of the bread, and thus extending the shelf life. Many studies have shown that EPSs produced by LAB can improve the growth of probiotics in the human body, thus improving the immune function. Of particular interest about possible prebiotic functions are EPSs produced by LAB. Long rye bread scalding fermentation technology can improve the texture, quality, and shelf life of bread, as well as functionally affect the human immune system.

The study was carried out to determine the effect of fermented dough (sourdough) containing lactic acid bacteria on the organoleptic quality and shelf life of bread. Spontaneous fermentation of three commonly used wheat flour was carried out for 120 hours (5 days) at ambient temperature and at 33⁰ C . The average total lactic acid bacteria counts during dough fermentation were 2.0 x 107, 1.8 x 107 and 1.7 x 107cfu/g for flour A, B and C fermented doughs respectively. A total of seven Lactobacillus species were isolated; Lactobacillus fermentum, Lactobacillus sanfransicensis, Lactobacillus casei, Lactobacillus pontis, Lactobacillus brevis, Lactobacillus plantarum and Lactoacillus acidophilus. Percentage overall acceptance of the experimental bread samples was highest (79.00%) in the bread samples with 20% fermented dough concentration. The highest minimum mould-free shelf life was 8 days in both the 15% and 20% fermented dough bread as compared to the control bread baked with yeast and commercially purchased bread. Finally, the use of fermented dough in bread production was found to improve the sensory quality and shelf life of bread.

Fermentation strains play a key role in the quality of bread. The combination of yeast and lactic acid bacteria (LAB) may effectively improve the function and nutritional properties of bread. In this study, the dough was fermented to make bread by using single strain (Saccharomyces cerevisiae, mode A), the combination of two strains (S. cerevisiae and Lactiplantibacillus plantarum, mode B; S. cerevisiae and Lactobacillus delbrueckii, mode C), or three strains (S. cerevisiae, L. plantarum, and L. delbrueckii, mode D). The specific volume, texture, and aroma substances of bread were evaluated. The possibility of mixed fermentation of selected yeast and LAB to replace natural fermentation dough was evaluated. The results showed that the specific volume of bread in mode B was 15.2% higher than that of mode A. The structure was softer and the taste was more vigorous in mode B bread. The content of volatile compounds was highest in mode B bread among the four mode bread. The characteristic flavors were ethyl 2-hydroxypropionate and z-3-hexenol. The cofermentation in mode B made the bread aroma richer and gave better aroma characteristics to bread. Therefore, the fermentation of S. cerevisiae and L. plantarum can be recommended to replace naturally fermented dough to improve the quality of bread. PRACTICAL APPLICATION: L. plantarum and L. delbrueckii, separately or together, assisted in yeast fermentation to make bread. The specific volume, texture, and aroma substances of bread were evaluated to replace natural fermented dough with mixed fermentation. L. plantarum-assisted yeast fermentation improved the specific volume, texture, and aroma of bread. The characteristic flavors were ethyl 2-hydroxypropionate and z-3-hexenol in bread. Therefore, the fermentation of S. cerevisiae and L. plantarum could replace naturally fermented dough to improve the quality of bread.

In recent days, there has been a general increase in the number of consumers who reject all synthetic additives in food; however research has revealed many novel applications for plum and raisin products as functional natural bakery ingredients. Raisin and prune concentrate and commercial sorbitol were incorporated into the Barbari bread formulation at different levels and their effects on the rheological, baking properties and shelf life of breads were evaluated. Supplemented dough absorbed more water than control. The presence of sorbitol, raisin and prune concentrate slightly increased dough development time. Firmness of breads decreased about the 15% for bread containing 4% raisin concentrate and 40% for bread containing 4% prune concentrate, and 40% for 1% sorbitol. Addition of raisin and prune concentrate showed more reduction in water activity in compare with control. Breads containing raisin concentrate, prune concentrate were sensory rated higher than those with sorbitol and control. Results showed that, raisin and prune concentrate could be used as a natural ingredient to prolong the shelf life and improve baking quality of Barbari bread.

Structure-function relationships of bacterial and enzymatically produced reuterans and dextran in sourdough bread baking application

The objective of this study was to improve the shelf life and nutrition quality of bread by combination of part‐baked frozen technology and white wheat flour replacement with 0, 10, 20 and 30% (w/w) of whole oat flour (WOF). Part‐baked breads were produced at 200C for 7 min followed by freezing at −18C for 1, 7, 14, 21 and 28 days and re‐baking at 230C for 8.5 min. Increasing the level of WOF enhanced water absorption, dough development time and dough softening while reduced dough stability time. Peak viscosity, trough and final viscosities reduced while pasting temperature increased. Baking weight loss increased with frozen storage time but reduced with addition of WOF. Frozen storage time and flour replacement enhanced bread density and firmness. Inclusion of maximum 10% WOF resulted in bread with similar sensory properties to those of control with a minimum shelf life of 28 days at −18C.Practical ApplicationsOat grains are well known for their health benefits and have been used in bread and other foods to improve their nutritional value. Oat bread has been produced already by conventional methods, while there is little information to show the possibility of production of oat bread using part‐baked frozen breads technology. This technology has a growing market as it can enhance the quality and shelf life of the bread. The results of this research indicated that replacement of maximum 10% wheat flour with whole oat flour can result in satisfactory part‐baked bread with frozen shelf life of 28 days. This study can provide further information on application of whole oat flour as an excellent source of dietary fiber (mainly β‐glucan) and bioactive compounds with health benefits in bread production industry in order to respond to the increasing demand for a wider variety of healthy breads with longer shelf life.

Effect of sourdough at different concentrations on quality and shelf life of bread

The object of the study is bread made from medium rye flour enriched with rowan powder. The study is devoted to the formation of quality and increase of the shelf life of bread. The technology of obtaining powder from Sorbus aucuparia involves freezing fruits, preliminary dehydration by osmotic dehydration, drying and grinding. It was found that rowan powder contains the highest amount of potassium (860 mg/100 g) and 6.7 % crude fiber. Rowan powder contains 1.72 mg/100 g of vitamin C, which gives it antioxidant properties. The experimental samples of bread from medium rye flour were made by the liquid sponge method. Rowan powder was added to samples D1, D2, and D3 in an amount of 5, 10, and 15 %, respectively. The control sample (C) was made according to a standard recipe. The analysis of the physicochemical parameters of bread quality showed that with an increase in the amount of rowan powder added, the acidity of the samples increased, but did not exceed the standard values. Rowan powder did not significantly affect the moisture content of the bread crumb. With the addition of 5 and 15 % powders, the moisture content was 46.7 and 46.6 %, respectively. In sample D2, which contained 10 % rowan powder, the moisture content was the lowest – 45.9 %. The effect of rowan powders on the storage ability of rye flour bread was investigated. It was found that mold appeared on the surface of sample C on the 5th day of storage. In the sample with a rowan powder content of 5 % – on the 12th day of storage, with a powder content of 10 % – on the 21st day of storage. On sample D3, mold was observed on the 16th day of storage. These results indicate that rowan powder can be used as a natural preservative that can significantly increase the shelf life of rye flour bread

Pane Toscano DOP, a traditional sourdough bread from Italy, has a limited shelf life, typically lasting only a few days. Extending its shelf life without the use of synthetic preservatives is essential to meet the rising demand for clean-label products and to reduce food waste. This study aimed to identify the most effective packaging strategy to extend the shelf life of Pane Toscano DOP. Two packaging systems were evaluated: single-package and bag-in-bag systems. In the single-package setup, bread was packaged in PET/PE under different headspace conditions: ambient air (C1), air + Everfresh® Spray (EVF, a natural aromatic extract) (C2), CO2 only (C3), and CO2 + EVF (C4). In the bag-in-bag system, bread was first placed in a PLA primary package containing air and then enclosed within a PET/PE secondary package filled with either air (T1), air + EVF (T2), CO2 only (T3), or CO2 + EVF (T4). Shelf life of bread under different packaging conditions was evaluated based on the appearance of visible mold growth. T4 exhibited the longest shelf life, maintaining acceptable quality for 41 days, followed by T3 with 34 days. Air packaged samples C1 and T1 had the shortest shelf life of only 6 days, while C2, T2, and C3 each maintained quality for 20 days. These findings demonstrate that the use of modified atmosphere packaging, bag-in-bag systems, and aromatic headspace extracts can significantly extend the shelf life of artisanal breads, such as Pane Toscano DOP. This approach offers viable alternatives to synthetic preservatives while maintaining traditional product formulations.

The shelf-life of bread is influenced by flour components, such as starch, composed of amylose and amylopectin. The aim was to test the effect of different balances of N (45, 90, 135 kg/ha) and P (48, 96 kg/ha) fertilizers on the flour characteristics and consequently the shelf-life of PDO Tuscan bread, stored in different modified atmosphere packaging (Ar, N2, Air). The amylose and phytochemical compounds were increased by N and decreased by the addition of P, but excessive doses of N (135 kg/ha) had a negative effect on flour quality. In the bread, the study highlighted the tendency of N2 and Ar, as storage filler gases, to reduce water loss, slow down the staling process, and prolong shelf-life. However, the most significant influence on shelf-life was related to the different fertilizations of wheat. In fact, when N was present in equal dose to P (90/96 or 45/48 kg/ha) or slightly higher (90/48 kg/ha), the bread tended to last longer over time. Instead, when these ratios were unbalanced in favor of N (135/48 or 135/96 kg/ha) and in favor of P (45/96 kg/ha), the shelf-life decreased considerably.

SummaryErsho is a well‐known as a source of lactic acid bacteria (LAB) and yeasts in Ethiopia. However, the utilisation of yeasts and LAB for bread production has not been previously studied. Therefore, the objective of the current study was to screen yeasts and LAB from ersho samples and determination of their bread production efficiency using a laboratory based experiment. Three LAB (1A, 13E, and 55A) and three yeasts (4A, 14D, and 54A) were screened and used to develop sourdough starters (4A13E, 14D55A, 54A1A, and 54A13E). The properties of BS4 bread made with 54A13E sourdough starter had more improved. The protein, TVC (total viable count), TFC (total fungal count), and shelf life of control bread were 13.38%, 3.1, 2.1 log cfu g−1, and 4 days, respectively. The protein, TVC, TFC, and shelf life of BS4 bread were 15.52%, 2.0, 1.4 log cfu g−1, and 7 days, respectively. Colour, texture, taste, odour, and overall acceptability mean scores of control bread were 6.6, 6.7, 6.9, 7.1, and 6.9, respectively. Colour, texture, taste, odour, and overall acceptability mean scores of BS4 bread were 8.6, 8.6, 6.4, 8.1, and 7.7, respectively. The results suggest that the use of sourdough starter in place of bakery yeast would be preferable when baking bread.