Buckwheat Dehuller and Optimization of Dehulling Parameters

Abstract

Pseudo cereals namely Buckwheat (Fagopyrum esculentum Moench.) is gluten-free grains characterized by an excellent nutrient profile. They have been used as nutritious ingredients in gluten-free formulations. They have been considered as underutilized food material in India and used mainly used in fasting days. In buckwheat kernel, outer hull or husk, which is comprises about 30% of the weight of the buckwheat grain. Since, it is inedible and not digested by human beings so it should be removed from buckwheat before processing. The performance evaluation of buckwheat dehuller was found to be influenced by the moisture content of the kernel (6 to 9% wb.), roller speed (500 to 1000 rpm) and feed rate (25 k to 75 kg/h). The overall performance was expressed in terms of dehulling efficiency and percent of broken kernel. Dehulling efficiency and percent of broken kernel increased with increase in roller speed up to 800 rpm, increase in feed rate up to 40 kg/h and then decreased further with increase in roller speed and feed rate and decrease in the kernel moisture content. The results of an optimization technique revealed that the best dehulling performance could be obtained if the system is operated at roller speed of 800 rpm and feed rate of 40 kg/h with moisture content of 6% wb. Under these conditions, the values of dehulling efficiency and percent of broken kernel were 66.61% and 6.19, respectively. Second order polynomial equations relating dehulling efficiency and percent of broken kernel to moisture content, impeller speed and feed rates for the buckwheat grains are developed. With this also dehulling operation was performed in double pass for this grains at optimized parameters in the machine to analyze the dehulling efficiency and percent of broken kernel in double pass and it was found, the dehulling efficiency and percent of broken kernel were 74.52% and 10.28% respectively.

AMC-made Impeller-type Buckwheat Dehuller and Optimization of Impeller Speed

“…Just as the higher roller speed induces rapid separation of the hull from the kernels, a similar frictional force may be induced on the body of the kernels, especially if they are quite fragile or soft. Similar observations were also made by Solanki et al (2018), Jain (1980), Joshi (1993 and Guptaa and Das (1999) in dehulling of buckwheat, paddy, pumpkin seed and sunflower seed, respectively.…”

“…In a study by Solanki et al, (2018) who used roller type dehusker set at 800 rpm, only 66.61% of DE was achieved. DE was significantly different between all the five levels of speed (Table 1).…”

“…Dehulling efficiency (DE) was measured as follows: 𝐷𝐸 = Mt -Mn Mt * 100…………………………. (Solanki et al, 2018) Where: Mn is a mass of grain left unhusked after the dehulling operation Mt is the total mass of grain fed into the hopper Broken percentage (B%) was measured as follows: 𝐵% = Ml Mt * 100 …………………… (Singh, Saha, & Mishra, 2010) Where: Ml is the broken kernels loss in the form of powder and broken grain after dehulling Mt is the total mass of grain fed into the hopper…”

“…Buckwheat (Fagopyrum esculentum Moench.) is a pseudocereal, having gluten-free grains characterized by an excellent nutrient profile (Solanki, Mridula, Kudos, & Gupta, 2018).…”

“…The outer hull or husk is mainly composed of cellulose and it comprises about 20-30% of the weight of the buckwheat grain depending on the variety. Since it is inedible and cannot be digested by the human digestive system the hull is removed from the buckwheat kernel before further processing into flour (Solanki et al, 2018). The hull has a smaller density than water and this allows easier removal of the hull from the kernel.…”