Chapter 3 - Organic farming of wheat and sourdough quality

Abstract

Both organic farming of wheat and sourdough bread production has gained market during past years due to the new wave of consumers that are concerned about natural foods, health, and life quality. However, the organic planting of wheat normally results in lower yields and kernels with inferior physical properties (test weight, thousand kernel weight, and wheat grade), lower protein content, and more damaged starch estimated with the falling number apparatus. The flours of these kernels usually contain lower gluten, dough rheological properties assessed with the farinograph, alveograph, rheofermentograph, and mixolab, and higher diastatic activity. The most affected organic wheat are the ones destined for bread making because flours usually have lower water absorption, dough development time, and dough stability. As a result, the bread usually has lower volumes and organoleptic scores. Sourdough technology is ideally suited to naturally extend the microbial and textural shelf life of bread and besides improve palatability and nutritional properties. Sourdoughs are mainly obtained from wheat and rye flours mixed with water and a starter of native homo and hetero-fermentative lactic acid bacteria in combination with yeasts. Recently, several culture techniques such as pyrosequencing, quantitative high-resolution melting PCR (Polymerase Chain Reaction), and quantitative PCR have been applied to study microbial diversity. The main sourdough bacteria are Lactobacillus sanfranciscensis, Lactobacillus plantarum, Lactobacillus sakei, Lactobacillus paralimentarius, Lactobacillus hammesii, Lactobacillus pentosus, and Lactobacillus curvatus, whereas the principal yeasts are Saccharomyces cerevisiae, S. exiguus, Kazachstania exigua, Issatchenkia orientalis, Candida humilis, Pichia kudriavzevii, Torulaspora delbrueckii, and Wickerhamomyces anomalus. Most investigations agree that sourdough bread made with organic flour yields bread with lower volume and quality mainly due to the weaker gluten associated with kernels harvested from organic farms.