Impact of par-baking and packaging on the microbial quality of par-baked wheat and sourdough bread

Assessing the Effect of Flour (White or Whole-Grain) and Process (Direct or Par-Baked) on the Mycotoxin Content of Bread in Spain

Bread is the staple food in many parts of the world. Like other foods, bread can contain mycotoxins resulting from microbial development throughout the supply chain (from field to table). In this study, baguette-style bread from small artisanal bakeries (direct) and supermarkets (par-baked loaves made by large companies) in Castile and Leon (Spain) was analyzed. Both white and whole-grain breads were collected from all retail outlets. The mycotoxins analyzed included deoxynivalenol (DON), ochratoxin (OTA), and aflatoxin B1 and B2 (AFB1, AFB2). All of the bread samples studied had mycotoxin levels below the maximum limits established by legislation. The presence of DON was higher than that of OTA, and AFB1 and AFB2 could not be quantified. Industrial breads had higher levels of DON and OTA (only in the whole-grain breads) compared to artisanal breads. However, no significant differences were found between white and industrial breads beyond those mentioned above. These results demonstrate that the established control chains ensure low mycotoxin content in bread of this type.

The potential of UVC decontamination to prolong shelf-life of par-baked bread

The effect of UVC (254 nm) treatment on the mould-free shelf-life of par-baked wholemeal, rye and six-grain bread was examined. Currently, these breads are par-baked, wrapped in high-density polyethylene (HDPE)-foil and transported or stored at room temperature for a couple of days before being full-baked and sold/consumed. Generally, after five days, these breads show signs of mould spoilage. A shelf-life increase in one or more days would already offer immense economical and logistic benefits for the baker or retailer. In this study, the parameters fluence rate (irradiation intensity), fluence (UV dose), distance to the UV-lamp (DTL) and number of layers of a common wrapping HDPE-foil (20 µm) were diversified. The breads were subjected to a UVC treatment (0-2502 mJ/cm²), packed and stored at room temperature for a period of 15 days (21.5 ± 0.8°C). Similar as for the breads, agar plates with mould spores of Aspergillus niger, Aspergillus montevidensis and Penicillium roqueforti were UVC treated (0-1664 mJ/cm²) and checked daily for visible mould growth during 15 days (25°C). Aspergillus niger showed the strongest resistance towards UVC, a fluence of 800 mJ/cm² was needed to inhibit growth during 15 days of storage, whereas for P. roqueforti and A. montevidensis, respectively, UV levels of 291 and 133 mJ/cm² were found sufficient. Furthermore, the shelf-life of wholemeal, rye and six-grain bread can be prolonged from 5 to 6, 8 and 9 days, respectively, using 2502 mJ/cm². The effect of higher UVC dosage on shelf-life reached a maximal level and was strongly impacted by the wide spread on data of mould-free shelf-life. The main factors influencing the potential of UV decontamination were the rough bread surface, differences in DTL, the possibility of post-contamination and UV permeability of packaging materials.

Probiotics in the Sourdough Bread Fermentation: Current Status

Sourdough fermentation is an ancient technique to ferment cereal flour that improves bread quality, bringing nutritional and health benefits. The fermented dough has a complex microbiome composed mainly of lactic acid bacteria and yeasts. During fermentation, the production of metabolites and chemical reactions occur, giving the product unique characteristics and a high sensory quality. Mastery of fermentation allows adjustment of gluten levels, delaying starch digestibility, and increasing the bio-accessibility of vitamins and minerals. This review focuses on the main steps of sourdough fermentation, the microorganisms involved, and advances in bread production with functional properties. The impact of probiotics on human health, the metabolites produced, and the main microbial enzymes used in the bakery industry are also discussed.

Role of lactic acid bacteria and yeasts in sourdough fermentation during breadmaking: Evaluation of postbiotic-like components and health benefits

Sourdough (SD) fermentation is a traditional biotechnological process used to improve the properties of baked goods. Nowadays, SD fermentation is studied for its potential health effects due to the presence of postbiotic-like components, which refer to a group of inanimate microorganisms and/or their components that confer health benefits on the host. Some postbiotic-like components reported in SD are non-viable microorganisms, short-chain fatty acids, bacteriocins, biosurfactants, secreted proteins/peptides, amino acids, flavonoids, exopolysaccharides, and other molecules. Temperature, pH, fermentation time, and the composition of lactic acid bacteria and yeasts in SD can impact the nutritional and sensory properties of bread and the postbiotic-like effect. Many in vivo studies in humans have associated the consumption of SD bread with higher satiety, lower glycemic responses, increased postprandial concentrations of short-chain fatty acids, and improvement in the symptoms of metabolic or gastrointestinal-related diseases. This review highlights the role of bacteria and yeasts used for SD, the formation of postbiotic-like components affected by SD fermentation and the baking process, and the implications of functional SD bread intake for human health. There are few studies characterizing the stability and properties of postbiotic-like components after the baking process. Therefore, further research is necessary to develop SD bread with postbiotic-related health benefits.

Dynamics of Volatile Compounds in Triticale Bread with Sourdough: From Flour to Bread

Triticale has been suggested for human consumption due to its valuable nutritional composition. The aim of this study was to evaluate volatile compound dynamics in the technological processes of triticale bread and triticale bread with sourdough prepared using Lactobacillus sanfranciscensis based cultures. Two types of sourdough ready-to-use sourdough and two-stage sourdough were used for bread making. Triticale bread without sourdough was used as a control. Volatile compounds from a headspace of flour blend, sourdough, as well as mixed dough, fermented dough, bread crumb and crust were extracted using solid-phase microextraction (SPME) in combination with gas chromatography/mass spectrometry. Alcohols, mainly 1-hexanol, were the main volatiles in the triticale flour blend, whereas in the headspace of sourdough samples ethyl-acetate, ethanol and acetic acid dominated. Two-stage sourdough after 30 min fermentation showed the highest sum of peak areas formed by 14 volatile compounds, resulting in substrates for further aroma development in bread. A total of 29 compounds were identified in the bread: in the crumb the dominant volatile compounds were alcohols, ketones, acids, but in the crust—alcohols, aldehydes, furans dominated. The use of two-stage sourdough provided a more diverse spectrum of volatile compounds. Such volatile compounds as ethanol, 3-methyl-1-butanol, 2-methyl-1-propanol, 2-hydroxy-2-butanone, 2-methylpropanoic acid, and acetic acid were identified in all the analysed samples in all stages of bread making.

The effect of the stale bread flour addition on flour and bread quality

In this study, the effect of the flour, which was obtained from stale bread, on flour and bread quality was investigated. The bread that was staled at refrigerator for 7 days was prepared as whole and crumb, and was grinded to convert into flour. The staled whole and crumb bread flours were stored at −18 °C and used to replace 0, 15, 30 and 45% of wheat flour. Then microbiological and physicochemical properties of flours; physical, textural and sensory properties of bread obtained from these composite flours were investigated. We concluded that stale bread flour could be used for bread production at the level of 15%. If the total bread production and consumption is considered, this addition level could provide a significant amount of waste bread recycling each year.

Modelling and validation of the antifungal activity of DL-3-phenyllactic acid and acetic acid on bread spoilage moulds

Most interesting antifungal compounds from sourdough fermentation are acetic acid (AA) and DL-3-phenyllactic acid (PLA). Although the role of pH on the activity of organic acids has been established long time ago, no information is available on the importance of undissociated acid (HA) expressed on the aqueous phase of bread (C_HA, mmole/L). Mostly, concentrations (mmole/kg dough or bread, C_TOT) and pH are given side by side. The aim of this study was to show the importance of C_HA for adequate comparison of in-vitro growth data with bread shelf-life. Growth of Penicillium paneum and Aspergillus niger was recorded using a micro-dilution assay with optical density measurements. Parameters such as a_w (0.94-0.98), pH (4.6-6.0), temperature (10-30 °C), time (0-8 days) and C_TOT (0-300 mM) were varied. Growth/no-growth models were developed and shelf-life tests of par-baked breads of 45 days at 20 °C were conducted. The modelled inhibitory concentrations of undissociated acid were comparable with the shelf-life test of bread: (PLA) 50 versus 39-84 mmol/L; (AA) 110 versus 110-169 mmol/L. This study showed the applicability of G/NG models for bread shelf-life prediction and highlighted the importance of CHA. Moreover, it was found that naturally present PLA in sourdough bread is insufficient to increase bread shelf-life.