Process improvement for enzymatic production of corn flour using papain

Abstract

Apparently, the increasing of national corn production and the number of substitutions reasearch about the wheat flour utilization using corn flour into a variety of processed food, such as noodles, cookies, biscuit or traditional and other processed foods, have not been able to encourage the growth of corn-based agroindustries as the corn flour quality produced by corn processing plant has not met the standards required. The objective of this research is to produce a corn flour production process engineering design using papain enzyme to produce corn flour with specification of 90% passes 80 mesh sieve and a 1.5% maximum of fat content. Research was initiated with characterization of corn samples (local corn Kodok variety and hybrid corn Pioneer 21 variety), degerminator modification, and the length of corn kernel soaking to make germ, tip cap and pericarp of endosperm separation more effective. It was continued with incubation of corn grits to decompose protein matrix on endosperm so it is easier to be milled, along with incubation process optimization. Optimization was performed using 2-Factor Completely Randomized Design, which enzyme concentration were 0.6; 0.7; 0.8; 0.9 and 1.0% or (425.4; 496.3; 567.2; 638.1; and 709 U/g) and incubation time period of 15, 18, 21 and 24 hours with two replications. Optimized respond variable was hardness of corn grits. Observation and examination carried out in this stage consist of yield, losses and fat content of grits generated by degermination, hardness and protein content of grits after incubation, grits morphology, starch granule birefringence and particle size distribution and visco-amylograph characteristic of corn flour produced. The next stage was the enzymatic corn flour production process design and production costs calculation. Addition of incubation process phase with the papain enzyme in the production process to improve corn flour particle size fineness was declared as novelty in this research. Degermination result showed the use of modified paddy polisher degerminator (type C degerminator) with 20 minutes corn seed soaking time gave the best result for both varieties with average grits yield 63.60%, weight losses 3.77%, and fat content decrease from 5.57% to 0.98% (db). On the other hand, the incubation using papain is capable to increase particle size fineness of corn flour produced hence it could meet the corn flour quality requirement (SNI No.01-3727-1995), at least 99% pass 60 mesh sieve and 70% pass 80 mesh sieves. Observation result using SEM showed that starch granule in local corn horny endosperm was spherical with size of 3-7 μm, while that of hybrid corn was polygonal with 3-12 μm size. In addition, there was protein matrix decomposition due to proteolytic enzyme work during papain incubation. The observation can resolve protein matrix decomposition by work of papain enzyme as shown by hardness and grits protein decreased after incubation. Observation result using polarized light microscope showed there was no birefringence damage on observed starch granule. The RVA testing result showed corn flour amylograph profile after incubation with papain 1% for 24 hours was similar to that of commercial corn starch. Optimization results using Minitab 16 software showed the optimum point of the incubation process for a local corn grits was at a concentration of 0.65% papain for 21.15 hours and for hybrid corn grits was at a concentration of 0.94% papain for 15.64 hours, while the flour particles passed 80-mesh sieve increased from 41.31% to 95.04% for local corn, and from 40.17% to 94.31% for hybrid corn compared to flour particle size without the addition of papain. Yield of corn flour milling for local and hybrid corn grits after incubation processed was 89,73% and 92,31% respectively. The production cost of corn flour enzymatically is higher than conventional one due to the additional costs for procurement papain and cysteine. Production costs of enzymatically corn flour without using activator (cysteine) is Rp 1.064 to1.169,-/kg, while the cost of production with the addition of cysteine is Rp 2.588 to 2.637,-/kg. Hardness difference between hybrid and local corn kernel directly impact the cost of production, so the higher corn kernel hardness, the higher the cost of production. By setting a profit margin of 15%, the selling price of corn flour enzymatic process without the use of cysteine is Rp.5.756,-/kg for local corn and Rp.5.963,-/kg for hybrid corn. This selling price of corn flour is cheaper than the price of wheat flour and rice flour that are sold in the market. In general, the better the quality of corn flour enzymatic process is expected to have a larger market share and a better selling price.