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Chapter 11 – Modified Atmospheres for the Control of Stored-Product Insects and Mites

Modified atmosphere packaging (MAP) as an alternative measure for controlling ten pests that attack processed food products

The use of modified atmospheres to control Sitophilus zeamais and Sitophilus oryzae on stored rice in Portugal

Interstitial concentrations of carbon dioxide and oxygen in stored canola, soybean, and wheat seeds under various conditions

. The metabolic rates, as expressed by oxygen (O2) consumption, carbon dioxide (CO2) production, and losses in wet and dry weights, were examined for adults of three strains of the red flour beetle Tribolium castaneum (Herbst), during exposure to two modified atmospheres (MAs). Exposure of a strain selected for resistance over twenty-one generations to an atmosphere of 65% CO2, 20% O2 and the balance nitrogen (N2), termed a high carbon dioxide concentration atmosphere (HCC) and exposure of an unselected strain to HCC, showed considerable levels of aerobic metabolism during exposure. For the unselected strain water loss and mobilization of energy reserves were rapid and mortality was followed by rapid desiccation. For the HCC-resistant strain water balance was maintained and energy reserves were utilized more slowly over a prolonged period. Exposure of a strain selected for resistance over twenty-one generations to a low oxygen concentration atmosphere (LOC) of 0.5% O2 in N2, and an unselected strain to LOC, revealed that even at 0.5% O2, metabolism was largely aerobic in both strains. Maintenance of water balance was not a major factor causing mortality of either strain during exposure to LOC. In air, metabolic rates of both the resistant strains were lower than that of the unselected strain.

Biological differences between strains of Tribolium castaneum selected for resistance to hypoxia and hypercarbia, and the unselected strain

The data obtained with warburg's manometry have revealed that grains such as rice, wheat, corn, peanuts, soybeans, red beans, sesame seeds, and coffee beans and their flours can adsorb a significant amount of CO2 gas. The mechanism of CO2 adsorption phenomenon was examined. The results obtained are summarized as follows: 1. Solubility of CO2 gas into the moisture and lipids of the grains is assumed to have a minor effect on this adsorption phenomenon. 2. Diffusion of CO2 gas into the grain is important in this phenomenon. This adsorption phenomenon is very similar to that observed in sorp-tion of gases by charcoal and silica gel, which sorbe gases into their many pores. The CO2 sorbed by the porous tissues of the grains is considered to remain in solid solution. 3. The amount of CO2 gas adsorbed by brown rice under varying partial pressures follows the classic sorption isoterm of Freundlich. 4. Microautoradiographic experiments show that the radioactivity of 14CO2 appears to be uniformly distributed throughout the tissues of germ and cotyledon. The adsorption phenomenon has led to the development of a new techni-que for skin-packaging, the Carbon Dioxide Exchange Method (CEM). This method and two modifications are explained. The merit and useful-ness of these techniques are discussed.

Mechanisms of carbon dioxide gas adsorp-tion by grains and its application to skin-packaging

穀類種実が炭酸ガス分圧の高い雰囲気中において, 炭酸ガスをかなり多量に吸着する事実を見いだした。その吸着量, 吸着速度, 温度依存性などについてワールブルグ検圧法によって検討した。その結果,1) モミ, 玄米, 白米, 小麦, ラッカセイ, ダイズ, コーヒー豆, ゴマ, トウモロコシ, ダイズ粉など種々の穀類種実ならびにその粉体に炭酸ガスが吸着されること。2) 炭酸ガスを吸着した種実を空気中あるいは炭酸ガス分圧の低い雰囲気中に移すと吸着量とほぼ等量の炭酸ガスが脱着すること。3) 最大吸着量は温度に依存し, 低温ほど大である。また種実の種類により異なること。などを見いだした。この現象に基づいた密着包装方法は穀類の品質保持に有効であるのみならず, 新しい包装方法として利用面が大きいと考えられる。

Mutsuo Kuga

Papers

Mechanisms of carbon dioxide gas adsorp-tion by grains and its application to skin-packaging

Carbon Dioxide Gas Adsorption by the Cereal Grains and its Application to Packaging (Part 1)