Document Type : Research Articles
Authors
1
PhD. Candidate of Animal Science, Faculty of Agriculture, Department of Animal Science, Ferdowsi University of Mashhad, Iran
2
Ferdowsi University of Mashhad
3
Professor, Chemistry Department, Ferdowsi University of Mashhad, Iran
Abstract
The effect of adding surfactants on appearance specification and nutrients content of processed corn grain using steam-flaked technique
Introduction Corn grain is one of the main sources of energy in the dairy cow diets; about 70% of corn's weight is due to starch. The starch granule is the basic unit of starch in corn endosperm and is a part of the starch–protein matrix. Its digestibility is influenced by the starch-protein matrix, granule morphology and size, as well as the degree of granule crystallinity and extent of granule damage. Cereal starch digestibility in ruminants is improved by an average of 10% by the application of heat, moisture and pressure during the steam flaking process. Depending on the processing method, the digestion site shifts from the rumen to the intestine, which is a significant factor in determining the rate of nutrient absorption that influences animal performance. Surface-active, foam-forming properties can increase water penetration and, consequently, the digestibility of processed grain. The most significant physicochemical property of surfactants is their ability to reduce surface tension, which is known as their interface activity. Low surface tension in rumen fluid may expedite food absorption and digestion. The main aim of this study was to evaluate the effect of various surfactants on nutrients content and appearance specification of steam-flacked corn grain.
Materials and methods In the present study, a steamed-flaked (SF) method was applied to processed corn grains. During the steaming, grains did not treated with the surfactants (CON) or treated with 1% Tween 80 (TW80),1% sodium dodecyl sulfate (SD), 1% Alum (AL), and 1% extract of Laurus nobilis (LN) as surfactants. The ethanolic extract of Laurus nobilis (Ln) was provided by dissolving 100 g of dried and ground Ln in 500 mL of 96% v/v ethanol/water and shaking for 72 hours, then, the plant extract was prepared using evaporating method. Non-treated or treated corn grains were then steamed for approximately 35 minutes at 96 °C. Scanning electron microscopy (SEM) to achieve the best scanning quality of starch granule structure and surface in processed corn grain with the surfactants through steam-flaked were taken. The samples were assayed at 25 kV accelerating voltage and 2500x magnification. Physical properties (Giger-Reverdin, 2000) and chemical composition (AOAC, 2012) were then examined. The Robertson and Eastwood, (1998) method was used to calculate water holding capacity. According to Aghajani et al. (2012), the grain density was calculated as the ratio of the grain's mass to the sample's particle volume. Crude protein and carbohydrate fractionations were carried out (Higgs et al., 2015). Protein fractions reported as NH3 (A1), soluble protein (A2), insoluble true protein (B1), fiber-bound protein (B2) and indigestible protein (C). Carbohydrates were divided into five fractions including A4 (water soluble carbohydrates or sugar), B1 (starch), B2 (soluble fiber), B3 (digestible fiber), and CC (ingestible fiber).
Results and discussion Scanning electron microscopy (SEM) analysis displayed that the processed corn grain using surfactants had larger surface starch granules than the SFC. All physical properties of the processed corn grain were significantly influenced by the chemically and physically procedures applied (P< 0.05). The highest bulk density was shown in LN (P< 0.05). Flaked corn grain treated with Tween 80 (TW80) had significantly (P< 0.05) higher volume compared with those of the others. The CP content of LN was higher than those of SD, TW80 and AL. Furthermore, the NDF content in SD was higher than that of LN and AL (P< 0.05). The total carbohydrates, non-fiber carbohydrates, digestible fiber and Indigestible fiber fractions of the processed corn grain were affected by the surfactant (P<0.05). The total carbohydrates and non-fiber carbohydrates fractions in LN were lower than that of the TW80, SD and AL. Digestible fiber and Indigestible fiber fractions were greater (P< 0.05) in AL than SD.
Conclusion All processed grains showed a different starch granule structure and surface compared with that of CON. Our findings illustrated that treating corn grain with the surfactants, applied in the present study during the steaming, improved the physically and chemically properties of the grain. Various alterations in carbohydrate fractions were traced in processed corn grain with the surfactants through steam-flaked procedure. The grain treated with extract of Laurus nobilis illustrated a reduction in both non fiber carbohydrates and soluble fiber concentration.
Keywords: Surfactant, Steamed, Tween 80, Bulk density, Carbohydrate
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