Effect of Four Herbal Plant Volatile Oil and Powder on the Maize Weevil (Sitophilus zeamais Motschulsky) Control During Storage of Organic Brown Rice, Variety Khao Dawk Mali 105
Abstract:
Organic rice consumption is widespread among health conscious consumers. However,
the maize weevil was often found in the organic brown rice storage and this caused damage and
difficulty. This experiment aimed to study the efficiency and the appropriate formulation of four
herbal plants, namely, galangal (Alpinia galanga (L.) Swartz.), turmeric (Curcuma longa L.), phlai (Zingiber cassumunar Roxb.), and kaffir lime (Citrus hystrix DC.) to reduce the damage of maize weevil and decrease the difficulty of the organic brown rice storage.
The study was divided into 6 experiments. 1) The efficiency of volatile oil of four herbs was investigated by two methods. The solutions of 2.5, 5 and 10% of volatile oil in 0.5 cc. acetone were directly mixed with 100 g. of organic brown rice. Each solution was dropped on a filter paper, put in tea bags and placed on 100 g. of organic brown rice kernels in a glass jar. 2) The effectiveness of the four powder herbs was tested by two methods: the 2.5, 5 and 10 g. of each herbal powders were directly mixed with 100 g. of organic brown rice and put in each tea bag and placed on 100 g. of organic brown rice in a glass jar. 3) The effectiveness of volatile oil with the same concentration as in Experiment 1 was examined by dropping 0.5 cc. of each solution on a filter paper, putting in each tea bag, then placing on 100 g. of organic brown rice in a plastic box. All samples were stored for 1, 7, 14, 21 and 28 days. 4) The effectiveness of the same amount of 4 herbal powder as in the Experiment 2 was studied by storing them for 1, 7, 14, 21 and 28 days. All kinds of herbal powder were put in each tea bag and placed on each 100 g. of organic brown rice in each plastic box. 5) The development of the four medicinal plants for commercial purpose was studied. 6) The sensory evaluation on color, smell and taste of the organic brown rice with the four herbs application to prevent the maize weevil was carried out. The Completely Randomized Design (CRD) with three replications was employed while the DMRT method was used for the means comparison.
The results showed that 10 percent of the phlai and galangal volatile oil solution in
acetone had the best effectiveness in controlling the maize weevil. All three amounts of the phlai
powder yielded the best result against insects, no maize weevil infested the organic brown rice. The
shelf-life of 1, 7 and 14 days of 10 percent volatile oil of phlai on the filter paper in tea bags, gave
the best result against maize weevil. The 10 g. of phlai powder in tea bag stored for 1, 7 and 14 days
was effective in controlling the infestation of maize weevil. In terms of commercially development,
it was found that four herbal plants at a concentration of 10 percent volatile oil from phlai on filter
paper and in tea bag showed the best control of maize weevil. Sensory analysis results of cooked
organic brown rice with herbs in various formulations and quantities showed that the acceptance
scores of the testers on color, smell and taste of cooked organic brown rice with herbs were higher
than those of the organic brown rice without herbs.