Hermetic storage of dry soybean (Glycine max): creating an effective modified atmosphere using soaked grain as O₂ depletor

Poster

Abstract

Hermetic storage of grains and oilseed has been proposed as a solution for reducing food losses in developing countries. However, to obtain full benefit of the hermetic storage it is required to achieve a low O₂ concentration (below 2%) or high CO₂ concentration (above 20%). The gas concentration inside the hermetic container is the result of the balance between the respiration and gas exchange rates with the outside (permeability and leakage). When the grain is dry, an insufficient modification in the internal atmosphere is achieved (exchange rate higher than respiration rate), allowing insect development and, hence, grain losses. This study focuses in creating an effective modified atmosphere during the hermetic storage of dry soybean using soaked grain as O₂ depletor. Three big bags with internal polyethylene liners of 70 µm thickness were filled with 590 kg of soybean (Glycine max, with 12.5% m.c.) and sealed. Gas concentration evolution was measured during 15 days (basal condition). Later, four plastic perforated bottles filled with of 4.3 kg of soaked soybean (44% m.c.) were inserted in each bag. The bags were re-sealed and gas concentration was measured during 45 days. Results indicated that the soaked soybean acted as an O₂ depletor, reducing the gas concentration to 1% in only 8 days, and maintained below 1% during 45 days. This research indicated that a small portion of soaked grain (0.4% dry matter (d.m.)) can be used to generate an effective modified atmosphere to prevent biological activity in the entire grain mass. This is a simple and inexpensive approach to reduce food losses under low cost hermetic storage.