The influence of heating method to the deterioration of frying oils during deep fat frying was examined in the three automatic test fryers with different method of heating, indirect heating system with Kanechlor, direct heating system with gas burner and heating tube system with gas burner (Fig.-1, 2, 3, Table-1). As a result, the apparent rate of deterioration increased in the order of direct heating, indirect heating and heating tube system. However, in this examination, the frying conditions such as specific surface area exposed to air, quantity of water vaporized and fat turnover rate were not the same. The further examination was carried out under equalized condition of main factors which affecting to the rate of fat deterioration with the indirect heating system and the direct heating system (Table-2, Fig.-4, 5). In the case of small thermal load, the rate of fat deterioration was almostly the same for the both heating methods. This fact may indicate that if the condition of main factors are the same, the rate of fat deterioration is also the same, regardless of the method of heating. However, in the case of large thermal load, a considerable difference was observed between the both heating methods. In the case of indirect heating system, by increasing the thermal load the fat turnover rate became greater, resulting the fat deterioration smaller and good frying quality was maintained during deep fat frying. On the other hand, in the case of direct heating system, the increase of acid value was observed in the last stage of test, and colour development and lowering of fat stability to autoxidation resulted. This fact may indicate that in the case of direct heating system, by the increase of thermal load, a remarkable over heating at the heating surface resulted thermalpolymerization and scission and thus the acids from scission induced the subsequent hydrolysis of fat. Accordingly, when the method of heating in a fryer is not proper and the temperature of heating surface rises over the temperature at which the scission of fat occurs, good frying quality will not be maintained during deep fat frying, resulting the deterioration by thermal decomposition, even if other factors are kept in good conditions.
This study shows that gas-liquid chromatography serves as a useful means for investigating the composition of the composite product formed by the thermal polymerization of methyl Linoleate. In particular, temperature-programmed gas-liquid chromatography is useful for the determination of the monomer and dimer contents. The monomer and dimer fractions can be quantitatively separated on column of 1.5% SE 30 silicon gum rubber-coated chromosorb W, with the column temperature being programmed from 200 to 310°C at a rate of 7.5°C per min, ; and the monomer and dimer contents can readily be determined from the peak areas. If desired, the trimer content can be estimated from the residue on the colomn under the assumption that the amount of the tetramers and higher polymers in the thermal polymerization products is negligibly small as compared with the trimer content. This temperature-programmed technique proved to be satisfactory when it is applied to the analysis of monomer-rich and dimer-rich samples from the fractional molecular distillation of thermally polymerized methyl Linoleate. On the other hand, isothermal gas-liquid chromatography served as a satisfactory means for the determination of monomeric isomers in methyl Linoleate-rich fraction separated by vacuum distillation. Results of analysis for monomeric isomers by isothermal gas-liquid chromatography suggest that octadecamonoenoate is formed during the thermal polymeri-zation of methyl linoleate.
The changes of soil removal efficiency of naturally soiled cloth with concentrations of detergents and builder were studied. The soil removal efficiency of about 70% was observed for the case of washing by only sodium tripolyphosphate-aqueous solution. The electron microscopic observations were carried out on the fiber surfaces washed by various washing solutions. It was observed that many inorganic soil particles were adhered on the fiber surface even at a very low soiling level corresponding to about 90% soil removal efficiency.
Effect of metals on the autoxidation of methyl oleate was investigated by observing the changes in peroxide value, iodine value, acid value and refractive index during autoxidation of the oleate in the presence of benzoyl peroxide (0.1%) and metal stearate (0.05% as metal) at 50°Cand 80°C. Such metals as Co (II), Cr (III), Mn (II), Fe (III), Pb (II) and Cu (II) remarkably accelerated the peroxide-formation and decompositon, while Ag, Zn, Mg, Ba, Sr, Ea, Hg and Cd showed little effect. Ni showed little effect at 50°C but accelerated the peroxide-formation at 80°C.
Authors studied the reaction conditions for preparation of the dialkyl dithiophosphates from 4 moles of alcohol (isopropyl, n- and sec-butyl, iso-amyl, n- and sec-hexyl, 4-methyl, 2-pentyl, cyclohexyl, 1- and 2-octyl, 2-ethylhexyl, or n-lauryl) and 1 mole of P2S5. When the alcohol having an alkyl chain of less than 4 carbon atoms (e.g. isopropyl, isobutyl etc.) is used as starting material, the advisable reaction temperature and time are 57 hr at 5060°C, while in case of alcohols having C5 C8 alkyl chain (e.g. 2-ethyl hexyl, 4-methyl, 2-pentyl etc.), it becomes 3 hr at 100°C respectively. When reaction temperature exceeds the above mentioned range, side reactions occur and both purity and yield of the product decrease. The antioxidation power of the Zn salt of these products was tested by measurements of the induction period for oxygen uptake in liquid paraffin. Induction period decreases according to the following order : 4-methyl-2-pentyl, cyclohexyl, sec-butyl, 2-ethyl hexyl, iso-amyl, n-hexyl, and 2-octyl which denote alkyl radical radical in the dialkyl dithiophos phates. Among them, initial three Zn salts are excellent as antioxidant.