Compendium of the most significant studies with reference to properties, intake, effects.

Taglieri I, Macaluso M, Bianchi A, Sanmartin C, Quartacci MF, Zinnai A, Venturi F. Overcoming bread quality decay concerns: main issues for bread shelf life as a function of biological leavening agents and different extra ingredients used in formulation. A review. J Sci Food Agric. 2021 Mar 30;101(5):1732-1743. doi: 10.1002/jsfa.10816.

Abstract. As is widely accepted, the quality decay of freshly baked bread that affects product shelf life is the result of a complex multifactorial process that involves physical staling, together with microbiological, chemical and sensorial spoilage. In this context, this paper provides a critical review of the recent literature about the main factors affecting shelf life of bread during post-baking. An overview of the recent findings about the mechanism of bread staling is firstly provided. Afterwards, the effect on staling induced by baker's yeasts and sourdough as well as by the extra ingredients commonly utilized for bread fortification is also addressed and discussed. As inclusion/exclusion criteria, only papers dealing with wheat bread and not with long-life bread or gluten-free bakery products are taken into consideration. Despite recent developments in international scientific literature, the whole mechanism that induces bread staling is far from being completely understood and the best analytical methods to be adopted to measure and/or describe in depth this process appear still debated. In this topic, the effects induced on bread shelf life by the use of biological leavening agents (baker's yeasts and sourdough) as well as by some extra ingredients included in the bread recipe have been individuated as two key issues to be addressed and discussed in terms of their influence on the kinetics of bread staling. © 2020 Society of Chemical Industry.

Fredensborg MH, Perry T, Mann J, Chisholm A, Rose M. Rising methods and leavening agents used in the production of bread do not impact the glycaemic index. Asia Pac J Clin Nutr. 2010;19(2):188-94. 

Abstract. The aim of this study was to compare the glycaemic index of breads produced using different rising methods and leavening agents. Eleven bread varieties were selected based on method of production, and divided between three groups of ten participants (mean +/- SD age 30.0 +/- 10.7 years and BMI 22.9 +/- 2.8). Standard glycaemic index testing protocol was implemented after an overnight fast, using glucose as the reference food, and collecting blood samples over a two-hour period. Glycemic index was calculated using the usual method. Additionally, incremental area under the curve data were log transformed and glycaemic index was calculated using regression analysis. Mean glycaemic index values of the breads in ascending order were as follows: Swiss Rye; 60, Long oat; 68, Sourdough+oats; 71, Long rye; 76, Short oat; 77, Short whole meal; 78, Long whole meal; 80, Sourdough; 82, Short rye; 82, Yeast; 88, and Desem; 92. There were significant differences in mean glycaemic index values between Swiss Rye and Yeast (p = 0.010), Swiss Rye and Desem (p = 0.007) and Sourdough+oats and Desem (p = 0.043). The rising method and leavening agents used in this study did not impact on the glycaemic index of the breads tested. Other factors, such as increased bread density, and the addition of whole grains may be required to produce bread with a low glycaemic index.

Kweon, M., Slade, L., Levine, H., Martin, R., & Souza, E. (2009). Exploration of sugar functionality in sugar‐snap and wire‐cut cookie baking: Implications for potential sucrose replacement or reduction. Cereal chemistry, 86(4), 425-433.

Abstract. The sugar series—xylose, glucose, fructose, and sucrose—can be used diagnostically to explore the effects of sugar type on differential scanning calorimetry (DSC), Rapid Visco-Analyser (RVA), and cookie baking performance because of the differences in glass-forming abilities (related to plasticization) and solubility parameters (related to solvent preference) of different sugars. Sugar concentration (% S), total solvent (TS), and dough formulation defined a core experimental design for cookie baking with the four sugar types and two baking methods. Although wire-cut cookie baking (66% S and 64 TS) showed the same trends as sugar-snap cookie baking (73% S and 79 TS) for diameter, height, and moisture content, the wire-cut formulation enabled greater discrimination among the effects of different sugar types on dough and cookie responses. Use of two different crystal sizes of sucrose confirmed the dominant impact of both gluten development during dough mixing and starch pasting during cookie baking on collapse: the greater rate of dissolution of smaller sucrose crystals resulted in greater surface crack for sugar-snap cookies, and lower height for wire-cut cookies. Because the historical definition of an “excellent quality cookie flour” is based on the performance of a flour in a cookie formulated with sucrose, the effect of sugar type on cookie making is to transform the apparent baking performance of a flour. Whereas formulation with sucrose optimizes the flour performance for cookie baking, formulation with xylose exaggerates the worst aspects of cookie flour functionality and makes even the best cookie flour look like a “poor quality cookie flour”. Use of solvent retention capacity (SRC), DSC, RVA, and wire-cut cookie baking as predictive research tools demonstrated that identification of a flour with an optimized SRC pattern is the key to successful mitigation of the detrimental effects of sucrose replacement on cookie processing and product attributes. 

Ficco DBM, Saia S, Beleggia R, Fragasso M, Giovanniello V, De Vita P. Milling overrides cultivar, leavening agent and baking mode on chemical and rheological traits and sensory perception of durum wheat breads. Sci Rep. 2017 Oct 19;7(1):13632. doi: 10.1038/s41598-017-14113-5.

Abstract. Smell and aroma are important determinants of consumer acceptance, so gaining deeper insight into bread smell and aroma perception is a research goal. Sixteen combinations of four variables were investigated, to evaluate the contributions of bread chemical and rheological properties and volatile organic compounds (VOCs) towards sensory acceptability of breads: genotypes (landrace vs. modern); types of flour (wholemeal vs. semolina); leavening agents (brewing yeast vs. sourdough starter); and baking modes (gas-fired vs. wood-fired). Milling had the greatest impact over the other treatments for the rheological and chemical properties, including for VOCs, with great impact on the sensory traits of the flours and breads. The processing phases had great impact on smell and aroma, as defined through formation of alcohols, aldehydes, terpenes, and other compounds (e.g., ethylbenzene, 2-pentylfuran, methoxyphenyl oxime). Leavening agent had great impact on sensory perception, although breads from the sourdough starter were perceived as with lower taste and colour than the brewing yeast. Baking mode had no relevant role on sensory perception. These data strongly undermine the belief of a 'better product' that is frequently attributed to old genotypes versus modern cultivars, and indicate that the milling and the bread-making processes determine the quality of the end product.

Carullo G, Scarpelli F, Belsito EL, Caputo P, Oliviero Rossi C, Mincione A, Leggio A, Crispini A, Restuccia D, Spizzirri UG, Aiello F. Formulation of New Baking (+)-Catechin Based Leavening Agents: Effects on Rheology, Sensory and Antioxidant Features during Muffin Preparation. Foods. 2020 Oct 29;9(11):1569. doi: 10.3390/foods9111569.

Abstract. The aim of this investigation was to prepare two solid mixtures containing a soluble polymorph of (+)-catechin and mucic (MUC) or tartaric (TAR) acids as new leavening agents. The solid mixtures were based on a polymorph of (+)-catechin, characterized through Powder X-ray Diffraction (PXRD) analysis and assayed in in vitro antioxidant and solubility assays. The dough samples were studied by dynamic rheological tests, while muffins were studied through Headspace Solid-Phase Microextraction (HS-SPME)/ Gas Chromatography-Mass Spectrometry (GC-MS) analysis to identify volatile compounds, in vitro tests to evaluate antioxidant properties, and sensory analyses. TAR powder showed a solubility in water almost one order of magnitude increased with respect to commercial (+)-catechin (40.0 against 4.6 mg mL-1) and increased antioxidant performances. In particular, TAR showed total phenolic content (TPC) and total antioxidant capacity (TAC) values of 0.0298 ± 0.021 and 0.0081 ± 0.0009 meq CT/g, while MUC showed better results in terms of 2,2-diphenyl-1-picrylhydrazyl) acid (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS), 0.518 ± 0.015 and 0.112 ± 0.010mg/mL, respectively. MS analysis identified different compounds derived from the lipid oxidation process. Muffins obtained using both powders showed interesting outcomes regarding dough process and appreciable appearance/olfactory/taste/texture profiles. Muffins obtained from TAR-based mixture showed also a total phenolic content of 0.00175 meq CT/g muffin, and almost two times improved TAC and scavenger activity against DPPH radical. The formulated powders could be used as suitable health-promoting ingredients in the food industry.

De Vuyst L, Vrancken G, Ravyts F, Rimaux T, Weckx S. Biodiversity, ecological determinants, and metabolic exploitation of sourdough microbiota. Food Microbiol. 2009 Oct;26(7):666-75. doi: 10.1016/j.fm.2009.07.012.

Abstract. Sourdough is a microbial ecosystem of lactic acid bacteria (LAB) and yeasts in a matrix of mainly cereal flour and water. Culture-dependent and culture-independent microbiological analysis together with metabolite target analyses of different sourdoughs enabled to understand this complex fermentation process. It is difficult to link the species diversity of the sourdough microbiota with the (geographical) type of sourdough and the flour used, although the type and quality of the latter is the main source of autochthonous LAB in spontaneous sourdough fermentations and plays a key role in establishing stable microbial consortia within a short time. Carbohydrate fermentation targeted towards maltose catabolism, the use of external alternative electron acceptors, amino acid transamination reactions, and/or the arginine deiminase pathway are metabolic activities that favour energy production, cofactor (re)cycling, and/or tolerance towards acid stress, and hence contribute to the competitiveness and dominance of certain species of LAB found in sourdoughs. Also, microbial interactions play an important role. The availability of genome sequences for several LAB species that are of importance in sourdough as well as technological advances in the fields of functional genomics, transcriptomics, and proteomics enable new approaches to study sourdough fermentations beyond the single species level and will allow an integral analysis of the metabolic activities and interactions taking place in sourdough. Finally, the implementation of selected starter cultures in sourdough technology is of pivotal importance for the industrial production of sourdoughs to be used as flavour carrier, texture-improving, or health-promoting dough ingredient.

Arendt EK, Ryan LA, Dal Bello F. Impact of sourdough on the texture of bread. Food Microbiol. 2007 Apr;24(2):165-74. doi: 10.1016/j.fm.2006.07.011.

Abstract. Sourdough has been used since ancient times and its ability to improve the quality and increase the shelf-life of bread has been widely described. During sourdough fermentation, lactic acid bacteria (LAB) produce a number of metabolites which have been shown to have a positive effect on the texture and staling of bread, e.g. organic acids, exopolysaccharides (EPS) and/or enzymes. EPS produced by LAB have the potential to replace more expensive hydrocolloids used as bread improvers. Organic acids affect the protein and starch fractions of flour. Additionally, the drop in pH associated with acid production causes an increase in the proteases and amylases activity of the flour, thus leading to a reduction in staling. While improving the textural qualities of bread, sourdough fermentation also results in increased mineral bioavailability and reduced phytate content. In this review we will be discussing the effect of sourdough on wheat and rye bread as well as the potential of sourdough to improve the quality of gluten-free bread.