Keito Boki

Bleaching of alkali-refined vegetable oils with clay minerals

Bleaching efficiencies of bentonites, montmorillonites and sepiolites for alkali-refined rapesseed, soybean, wheatgerm, safflower, corn, cottonseed and sunflower oils were investigated by a batch method at 110°C. The sepiolites with more acid sites at −5.6 < Ho ≥ −3.0 were the most effective in bleaching of each alkali-refined oil. Surface area and acidity at −5.6>Ho ≥ −3.0 were highly significant with bleaching efficiency. The sepiolites (numbers 2 and 3) were more suitable than standard activated clay because they were more effective both in retaining tocopherols and in reducing free fatty acids after bleaching.

Bleaching rapeseed and soybean oils with synthetic adsorbents and attapulgites

Efficiencies of synthetic adsorbents and attapulgites in bleaching alkali-refined rapeseed and soybean oils ranged from 13–53% and 93–97%, respectively. The Freundlich equation was more applicable than the Langmuir equation to the experimental adsorption isotherms of β-carotene on attapulgites. Bleaching with attapulgites reduced tocopherols by 12.5–29.5% in rapeseed oil and by 18.9–44.8% in soybean oil. Cosmetic-grade attapulgite was superior to the others in bleaching efficiency, equilibrium amount adsorbed and removal of free fatty acids.

Adsorption isotherms of pigments from alkali-refined vegetable oils with clay minerals

Adsorption isotherms of pigments from alkali-refined oils (rapeseed, soybean, wheatgerm, safflower, corn, cottonseed and sunflower) were measured to investigate the applicability of the Langmuir and Freundlich equations and to elucidate the adsorption characteristics of pigments on sepiolites and standard activated clay. The Freundlich equation was more applicable to the experimental adsorption isotherms. The equilibrium amount adsorbed, acidity, pore size distribution and inflection of the Freundlich isotherms could be explained by assuming that pigments were adsorbed on the stronger acid sites in smaller pores at low concentration, and then in the larger ones when the concentration increased. The amount adsorbed increased with a rise in adsorption temperatures from 70 to 110°C, and the heat of adsorption was below 10 kcal/mol. The results indicate that pigments were physically adsorbed on the acid sites activated at higher adsorption temperatures.

Effects of filtration through activated carbons on peroxide, thiobarbituric acid and carbonyl values of autoxidized soybean oil

Effects of filtration bleaching on peroxide value (PV), thiobarbituric acid value (TAV) and carbonyl value (CV) of autoxidized soybean oil were investigated by using twenty-three kinds of activated carbon in order to improve oil quality. From the decreases in PV, TAV and CV and from the physical and chemical properties of activated carbons, it was suggested that hydroperoxides, aldehydes and ketones were adsorbed on the acid sites distributed over the surface or within the pores of the activated carbons while the autoxidized soybean oil flowed through the packed column. The residual tocopherols in autoxidized soybean oil and treated soybean oil were determined during storage. The decrease in oxidative stability of treated soybean oil seemed to be caused by elimination ofα-,β-andγ-tocopherols.δ-Tocopherol was chemically more stable thanα-,β- andγ-tocopherols in autoxidized soybean oil.

Effects of filtration through bleaching media on thiobarbituric acid and carbonyl values of autoxidized soybean oil

Effects of filtration bleaching on thiobarbituric acid values (TAV) and carbonyl values (CV) of autoxidized soybean oil were investigated by using sixteen kinds of bleaching media in order to improve oil quality. The standard activated clay was the most effective in reducing the amounts of aldehydes and ketones in autoxidized soybean oil. From the decreases in TVA and CV and physical and chemical properties of media, it was concluded that decreases of TAV and CV are mainly dominated by the acidity over the highest range, +1.5∼−5.6, rather than the acidity over the lower acid strength ranges, total acidity or specific surface area of media. From the results of chemical composition and acidity over the highest range (+1.5∼−5.6) of the clays and TAV or CV reduction by using the heattreated clays, it was suggested that the acidity over the highest range originated from the water contained between layers and bound water in the clay.

Uptake of Heterocyclic Aromatic Amine by Insoluble Dietary Fiber in Artificial Gastric and Intestinal Juice

ObjectivesThe purpose of the presentin vitro study was to predict to what extent dietary fiber (DF) takes up heterocyclic aromatic amine (HAA) and how DF acts to intercept HAAsin vivo.MethodsThe sorption isotherms of 2-amino-3-methyl-3H-imidazo[4,5-f]quinoline (IQ), 2-amino-3,4-dimethyl-3H-imidazo[4,5-f]quinoline (MeIQ), 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole acetate (Trp-P-1), and 3-amino-1-methyl-5H-pyrido[4,3-b]indole acetate (Trp-P-2) for DF were measured in artificial intestinal juice (AIJ) and artificial gastric juice (AGJ) at 37°C. The desorption of HAA from DF was measured in AGJ and AIJ.ResultsThe sorption isotherms were statistically classified into four types. The percentage of Trp-Ps taken up by carboxymethylated cellulose (CMC) and agar in AGJ (pH, 1.2) was 52–56% and 58–78%, respectively. On the other hand, the percentage of Trp-Ps taken up by CMC and agar in AIJ (pH, 6.8) was 97–98% and 87–89%, respectively. The percentage of IQ and MeIQ sorbed by CMC was 21–27% in AGJ and 100% in AIJ. Collagen and chitin did not remove any HAAs in AGJ, but removed 4–69% in AIJ. In the four-component solution, the percentage of HAA taken up by DF was almost the same or significantly increased, with a few exceptions, as compared with that in the one-component solution.ConclusionThe results indicated that MeIQ is mainly held on the surface of CMC in AIJ, and that Trp-P-1 and Trp-P-2 are mainly held in the interior of agar in AGJ and AIJ. The results on sorption-desorptionin vitro indicate that sorbed HAAs in the stomach are held more firmly by agar than by CMC while DF passes through the human intestinal tract. CMC and agar would be expected to be more useful than collagen and chitin as agents intercepting HAAs.

Inhibition of Trilinolein in Adsorption of .BETA.-Carotene on Attapulgite and Sepiolite.

Adsorption characteristics of β-carotene from triglyceride n-hexane solution were invesitigated to elucidate the inhibition effect of trilinolein on β-carotene adsorption by attapulgites and sepiolites. The inhibition effect of trilinolein was larger than that of triolein in the initial adsorption rate and the adsorbed amount of β-carotene. Inhibition of trilinolein in maximum amount of β-carotene adsorbed on clay minerals was 1.2 times as strong as that of triolein. It was suggested that adsorption of β-carotene on clay minerals was inhibited due to binding trilinolein to β-carotene in n-hexane. The total inhibition effect was not in direct proportion to the number or the concentration of triglycerides coexisted in n-hexane.

Moisture Sorption Characteristics of Steer Hide Collagen Fibers Treated with Calcium Hydroxide

Hydration properties of steer hide collagen fibers treated with calcium hydroxide were investigated based on the adsorption-desorption moisture isotherm at 11 to 30oC. An increase in the amount sorbed on alkali-treated collagen was explained due to the increase in the number of carboxyl- and amino-groups. In the range of water activity of 0 to 0.85, a hysteresis loop was observed. The results of heat of sorption suggest that sorbed moistures were composed of the moistures bound on the active sites and those fixed in the inter triple helix and inter microfibrillar phase. The Freundlich equation, which represents a monolayer model, fitted the adsorption isotherm of untreated collagen fiber. The Henderson and Chung and Phost equations which represent an experimental model proposed for food sorption fitted the adsorption isotherm of alkali-treated collagen fiber.

Effects of Several Manufacturing Conditions on the Surface Properties of Magnesium Silicates

In order to examine the effects of several manufacturing conditions on the surface physical properties of magnesium silicates, five kinds of magnesium silicates were produced by four different methods.SiO2/MgO mole ratio, apparent specific volume, specific surface area, acid strength and acidity at pKa=+1.5 and pKa=+3.3 were measured. It was found that these physical properties were related to the adsorptive power for dyes (M·B, M·G, S, B·M·G) and to pH condition during manufacturing of magnesium silicates.Magnesium silicate with the strongest adsorptive power had the following properties: (1) larger SiO2/MgO ratio, (2) smaller apparent specific volume and (3) smaller specific surface area.Acid strength and acidity of the surface of magnesium silicates had no relation to the adsorptive power for dyes.