The Effect of Chemical Processing Through Steam Flaking or Steam Infrared Flaking of Barley Grain on Physical and Chemical Properties, and Protein and Carbohydrates Fractionation

Introduction: Barley grain is the main feed for cattle in many regions of the world. The digestibility of barley grain is restricted by its fibrous shell and intact pericarp. The extent and rate of digestion of ruminal carbohydrates and barley grain can be manipulated through processing. Barley processing can be a valuable tool to optimize the production of lactating dairy cows. The application of combinations of heat, moisture, time and mechanical action may influence the quality of processed barley grains. Micronization is a rapid thermal treatment (30-90s) using infrared radiation and has great application potential in the feed industry due to simple construction and operation. It has been demonstrated in a number of experiments that organic acids, including lactic acid and malic acid, alter the chemical composition and nutritional value of cereals. Essential oils are naturally occurring plant products that are rich in chemical composition and have various biological properties. The interactions between starch and phenolic compounds have attracted increasing attention in recent years. The aim of this study was developed to determine the impact of chemical processing through steam flaking or steam-infrared flaking of barley grain on physical and chemical properties, and protein and carbohydrate fractionations. Materials and Methods: The ethanolic Foeniculum vulgare (Pv) or Acanthophyllum (Ap) extract were prepared by dissolving 100 g of dried and ground Pv or Ap in 500 mL of 96% v/v ethanol/water and shaking for 72 h. Then, the extracts were filtered through a Whatman No. 1 paper (Whatman Ltd., Maidstone, England). The residual solvent from the ethanolic extract was removed using a rotary evaporator. Barley grain was then mixed thoroughly with distilled water at a ratio of 10% by weight and treated with either 1% lactic acid (La) or 1% malic acid (Ma). Subsequently, the samples were treated with a 5% solution of Ap or Pv. The processed grains were steamed for approximately 35 minutes at 96°C. The steam-cooked grains were then divided into two groups, with one group exposed to infrared radiation for 55 seconds (SIF). All cooked grains were then flaked (SF) using a designed flaker machine. Physical properties, following the Giger-Reverdin method (2000), and chemical composition, based on AOAC standards (2012), of the samples were then analyzed. Crude protein was calculated as N × 625. NDF and ADF contents were determined according to the method proposed by Van Suste et al. (1991). Starch content was evaluated using anthrone and sulfuric acid (Rose et al., 1991). Bulk density was determined by weighing 100 ml of the samples. Water holding capacity was assessed using the method described by Robertson and Eastwood (1998).The grain density was defined as the ratio of the mass of the grain to the particle volume occupied by the sample (Aghajani et al., 2012). Crude protein and carbohydrate fractionations were performed according to Higgs et al (2015). Carbohydrates were divided into five fractions based on different degradation rates in the rumen: A4 (water soluble carbohydrates or sugar), B1 (starch), B2 (soluble fiber), B3 (digestible fiber), and CC (ingestible fiber). Results and Discussion: All the physical properties of the processed barley grain were significantly affected by chemically and physically methods applied in this study (P < 0.05). The highest bulk density and water holding capacity were shown in both SF and SIF processing. The results of this study indicated that the contents of CP, ADF, NDF, EE,Ash, amylose and amylopectine were significantly affected by the chemically and physically processing (P< 0.05). The CP content of the grains treated with Ap and Ma had higher compared with that of Pv and La. In addition, NDF concentration of the grains processed by SF method was greater than that of SIF (P < 0.05). Both CP and NDF content of the processed grain were higher for (SIFBApMa) and (SIFBApLa) rather than those of the other treatments (P< 0.05). The soluble true protein, insoluble true protein and indigestible protein fractions of the processed grain were affected by both chemically and physically processing methods (P < 0.05). The soluble true protein fraction in the grain treated by Ap was greater than that of the Pv. The indigestible protein fraction increased in Pv treatments compared the Ap treatments. Significant differences were found between the processed grains regarding the total carbohydrates, non-fiber carbohydrates, soluble fiber, digestible fiber and Indigestible fiber carbohydrate fractions (P<0.05). The carbohydrates, non-fiber carbohydrates and soluble fiber carbohydrate fractions were greater (P< 0.05) in the SIF than those of SF method. Digestible fiber and Indigestible fiber fractions were lower (P< 0.05) in La than Ma treatments. Conclusion Our results demonstrate that processed barley grain with organic acids (Malic acid or Lactic acid) and using extracts of Acanthophyllum or Foeniculum vulgare accumpany through physical processing (steam flaking or steam- infrared -flaking) make an improvement in nutritional value of the grain. In this study, bulk density and water holding capacity were greater in steam flaking rather than steam-infrared-flaking method. Regarding the CP fractionations, processed barley grain with Acanthophyllum extract through steam-infrared-flaking displayed significant alter in the fractions. Lactic acid processed grain through steam-infrared-flaking showed an enhancedment in both non fiber carbohydrates and soluble fiber concentration of the grain. Present data showed a positive impact of both chemically and physically methods applied in barely grain, however, further investigation regarding protein and carbohydrate molecular responses are needed to be evaluated.