Rheological behavior of emmer, spelt and khorasan flours

Abstract

Wheat is one of the major world agricultural products, extensively grown worldwide due to the unique dough rheological properties and the bread-baking quality of its flour (Arzani & Ashraf, 2017). According to EUROSTAT (2020), in 2019, the harvested production of cereals in the EU-27 was 299.3 million tons from which common wheat and spelt account for 131.8 million tons or 44% of total cereals production.Cultivated area of common wheat and spelt in EU in 2019 was 24.2 million ha (EUROSTAT, 2020). On the other hand, the production of the ancient wheat species, such as, diploid einkorn (Triticum monococcum L.), tetraploid emmer (T. dicoccum L.), and hexaploid spelt (T. spelta L.) is suppressed (Geisslitz et al., 2018). In Serbia, spelt is cultivated on the area of 157.9 ha, mostly in the northern region called Vojvodina (120.04 ha) (Vojnov et al., 2020), while emmer and khorasan are produced in a significantly smaller scale compared to spelt. The main reason behind this is low yield (Geisslitz et al., 2018), difficulties related to the processing of grains, as well as inferior technological quality (Arzani & Ashraf, 2017) compared to the common wheat. Regardless of these shortcomings, ancient wheat varieties are considered environment friendly because of its disease resistance and low fertilizer input. Moreover, considering high adaptability to the altered climatic conditions, ancient wheat represents a valuable genetic resource of interest to breeders (Boukid et al., 2018).

Techno-Functional Performance of Emmer, Spelt and Khorasan in Spontaneously Fermented Sourdough Bread

“…On the contrary, emmer sourdough exhibited the lowest elastic modulus and the highest tan δ values, suggesting that emmer flour produced sourdough with the lowest strength and elasticity compared with other wheat varieties. This was in agreement with the fact that emmer flour was characterised with the lowest gluten index values in comparison with spelt and khorasan flour [17] and therefore resulted in a higher contribution of viscous over elastic gluten component in the measured sourdough system.…”

“…Among sourdough samples, khorasan sourdough had the highest values of modulus G’ and the lowest values of tan δ, thus exhibiting the properties of rigid and stiff material. This behaviour could be related to the lower wet gluten content and higher gluten index value [ 17 ] of khorasan sourdough in comparison with other samples, resulting in a higher amount of elastic over viscous gluten components. On the contrary, emmer sourdough exhibited the lowest elastic modulus and the highest tan δ values, suggesting that emmer flour produced sourdough with the lowest strength and elasticity compared with other wheat varieties.…”

“…Among sourdough breads, wheat and spelt samples were characterised with the highest specific volume, while bread prepared from khorasan sourdough and flour had the lowest specific volume. This could be related to the lowest protein content (khorasan, 11.49%; spelt, 15.87%; emmer, 15.99%) and the wet gluten value of khorasan flour in comparison with other ancient wheat varieties [ 17 ], as well as the low quantity of CO 2 produced in the fermentation step. Moreover, khorasan sourdough was characterised by high stiffness ( Figure 1 ) and dense structure ( Figure 2 ), which could not expand enough to entrap formed gas bubbles.…”

“…Previous investigations by Bojnanska and Francakova [ 23 ], Boukid et al, [ 24 ] and Sumczynski et al, [ 25 ] also revealed that ancient wheat varieties were generally characterised by higher protein content than the modern wheats. However, it was also found that the gluten structure of these proteins was weak due to higher gliadin/glutenin ratios in comparison with the modern wheat variety [ 17 , 26 ].…”

“…Previous investigations by Bojnanska and Francakova [23], Boukid et al, [24] and Sumczynski et al, [25] also revealed that ancient wheat varieties were generally characterised by higher protein content than the modern wheats. However, it was also found that the gluten structure of these proteins was weak due to higher gliadin/glutenin ratios in comparison with the modern wheat variety [17,26]. Water represents one of the most important parameters influencing microbial spoilage of foods; the water activity (a w ) factor is a valuable tool for predicting microbial growth and metabolic activity [27].…”