Detection of Chemiluminescence Produced during Beer Oxidation

Chemiluminescence (CL) produced in beer was detected using the single photoelectron counting system. CL production did not occur in a nitrogen atmosphere but did occur in air and was dependent on incubation temperatures. It was inhibited by the addition of ascorbic acid. CL analysis should provide useful information in the study of oxidative deterioration of beer.     

Grain Growth and Phase Transformation of Titanium Oxide During Calcination

Additions of NiO, CoO, MnO₂, Fe₂O₃, and CuO promote the anatase-rutile transformation and grain growth of TiO₂. Additions of Na₂O and WO₃ retard the transformation and have no effect on the grain growth. The addition of MoO₃ strongly promotes the grain growth but has only a slight effect on the phase transformation. Both the grain growth and transformation are promoted slightly by Cr₂O₃. The transformation is significantly affected by the method of preparing TiO₂. The grain size of TiO₂ heated in H₂ exceeds that of TiO₂ heated in O₂, in air, in argon, and in vacuum. The rate of transformation decreases with an increase in the partial pressure of oxygen of the atmosphere.     

Generation of Mannitol from Copra Meal

Saccharification of copra meal with hydrochloric acid was found to be suitable method for forming reducing sugars. The presence of protein and lignin in the meal did not have a significant effect on the yield of reducing sugars. Borohydride reduction of the reducing sugars gave sugar alcohols in 44% yield based on the raw material or 81% based on carbohydrate content. The sugar alcohol mixture contained 66% mannitol, 24% sorbitol and 5% galactitol. The recovery of hydrochloric acid which renders the process more economically feasible was done by vacuum distillation.     

High Temperature Storage Effect on Longevity of Rice Seeds

Storage of Indica (Oryza sativa L. cv. Katakutara) and Japonica (Oryza sativa L. cv. Kusabue) rice seeds at 30° and 40°C for 2 months in the dark did not result in the loss of viability in both cultivars. Storage at 60°C, however, resulted in a complete loss of germination after 45 days in the case of Kusabue while the Katakutara rice seeds retained the germination potential well above 95%. Corresponding increases in the linoleic acid content of the free fatty acid fraction and TBA values of the extracted lipid fraction were also observed in Kusabue rice seeds. The investigation indicated that the Indica rice seeds were better protected than the Japonica rice seeds by the enclosing rice hull during the storage period.     

Detection of Free Radicals in Beer Oxidation

Short-lived radicals produced during the incubation of beer at 60°C were detected by electron spin resonance (ESR) spectroscopic analysis using N-tert-butyl-α-phenylnitrone (PBN) as a spin trapping reagent. The hyperfine splitting (hfs) constants were 15.7 ± 0.2 G and 3.2 ± 0.2 G for α_N and a^β_H, respectively. The hfs constants of PBN adducts produced by Co⁶⁰γ irradiation were 15.6 ± 0.3 G and 3.1 ± 0.2 G for α_N and α^β_H in beer and 15.7 ± 0.3 G and 3.3 ± 0.3 G for α_N and α^β_H in double distilled water. It is proposed, therefore, that short-lived radicals produced during the incubation of beer at 60°C may be hydroxyl radicals.     

Sintering of High-Purity Nickel Oxide, II

The effects of particle size, compacting pressure, additives, and mode of preparation on the sintering of nickel oxide are presented. A low calcining temperature results in a high bulk density of a sintered compact. No appreciable change in the rate of sintering is found above 1000 kg. per sq. cm., whereas the unheated density increases with increasing pressures. Additions of CaO promote sintering, additions of Na₂O, Fe₂O₃, and Al₂O₃ retard sintering, and CeO₂ and Ag₂O have no effect; B₂O₃ accelerates grain growth but retards densification. Nickel oxide from oxalate has a small rate of sintering as compared with nickel oxides from hydroxide, nitrate, and carbonate. The effects of the mode of preparation of nickel oxide are discussed in view of the activation energy of electronic conductivity and particle size.     

Free radical reactions in beer during pasteurization

Oxidative reactions during beer pasterization were studied using chemiluminescence (CL) and electron spin resonance (ESR) analyses. the CL production of beer was acclerated by pasteurization and the maximum CL intensity appeared sooner than that in non-pasteurized beer. Beers pasteurized with 15–30 pasteurization units (P.U) had the same CL producing activities as the non-pasteurized beers stored at 20°C for 6–10 days. Free radicals were produced and some of them were consumed by beer oxidation during pasteurization. It seems that free radicals were consumed by beer oxidation during pasteurization. It seems that free radical reactions occur in beer during pasteurization and that the degree of oxidation during pasteurization generally corresponded to that of non-pasteurized beer stored at room temperature for about 1 wee.     

Evaluation of Beer Deterioration by Chemiluminescence

The application of chemiluminescence (CL) analysis for the evaluation of staling beer was studied. Commercial Japanese lager beer was stored at 30°C, 37°C, and 60°C and its CL generation was analyzed at 60°C. The CL production was accelerated to a greater degree and its intensity reached maximum level more rapidly with increase in incubation temperature and/or time. The sum of the CL intensity for the first 1 hr showed a good relationship with staling degree in mean flavor panel scores. Therefore, CL determination may be useful for evaluating oxidation deterioration of beer.     

Effects of Dough Materials on Flavor Formation in Baked Cookies

The effects of dough materials on flavor formation in baked cookies were investigated in detail. The baked cookies were prepared from wheat flour, eggs, butter, sugar and sodium bicarbonate and heated at 150°C for 10 min. This dough was extracted with methanol/water (3:1,v/v) and the extracts were submitted to HPLC. The two main peaks, among 10 peaks detected, were identified as 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one (DDMP) and 5-hydroxymethyl-furfural (HMF), respectively. DDMP seemed to be a key substance enhancing the good qualities of cookies with its favorable aroma. The generation of DDMP in baking was affected by the addition of proteins and amino acies, and among these, ovalbumin, proline, arginine and histidine strongly enhanced the DDMP generation.     

Analysis of Aldehyde-bisulfites in Beer by HPLC-Fluorescence Detection with Post-column Derivatization

An analytical method was based on the aldehyde-bisulfite (separated by HPLC) reaction with o-phthalaldehyde in the presence of ammonium acetate, producing a fluorescent compound. Detection limits of alkanalbisulfite (from formaldehyde- to octylaldehyde-bisulfite) and 2-alkenalbisulfite (from trans-2-hexenal- to trans-2-nonenal-bisulfite) ranged from 5 nM to 25 nM. The method was less sensitive for free sulfite (detection limit 100 μM) than for aldehyde-bisulfite. Increasing acetaldehyde-bisulfite with addition of 25 mM acetaldehyde to a beer sample showed free sulfite in the beer. Free sulfite and acetaldehyde-bisulfite were detected in commercial beers but other aldehyde-bisulfites were not.