Gas plasma generated and applied under two different systems, atmospheric pressure plasma and low pressure plasma, was used to investigate the inactivation efficacy on the seedborne pathogenic fungus, Rhizoctonia solani, which had been artificially introduced to brassicaceous seeds. Treatment with atmospheric plasma for 10 min markedly reduced the R. solani survival rate from 100% to 3% but delayed seed germination. The low pressure plasma treatment reduced the fungal survival rate from 83% to 1.7% after 10 min and the inactivation effect was dependent on the treatment time. The seed germination rate after treatment with the low pressure plasma was not significantly different from that of untreated seeds. The air temperature around the seeds in the low pressure system was lower than that of the atmospheric system. These results suggested that gas plasma treatment under low pressure could be effective in disinfecting the seeds without damaging them.

The aim of this study was to investigate the effect of low-pressure plasma treatment on seed disinfection and the possible mechanisms underlying this effect. Seed-borne disease refers to plant diseases that are transmitted by seeds; seed disinfection is an important technique for prevention of such diseases. In this study, the effectiveness of low-pressure plasma treatment in the inactivation of the seed-borne plant pathogenic bacterium, Xanthomonas campestris, inoculated on cruciferous seeds, was evaluated. The highest inactivation effect was observed when the treatment voltage and argon gas flow rate were 5.5 kV and 0.5 L/min, respectively. The viable cell number of X. campestris was 6.6 log cfu/seed before plasma treatment, and decreased by 3.9 log after 5 min of treatment and by 6.6 log after 40 min. Ethidium monoazide treatment and quantitative real-time PCR results indicated that both the cell membrane and target DNA region were damaged following 5 min of plasma treatment. Although both heat and ozone were generated during the plasma treatment, the contribution of both factors to the inactivation of X. campestris was small by itself in our low-pressure plasma system. Overall, we have shown that our low-pressure plasma system has great applicability to controlling plant pathogenic bacterium contamination of seeds.

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Food is a basic necessity for human survival, but it is still the vehicle for the transmission of food borne disease. Various studies have examined the roles of spices, herbs, nuts, and semidried fruits, making the need for safe and convenient methods of decontamination a necessity. The current study determined the bacterial and fungal loads of 26 spices and herbs, 5 nuts, 10 semi-dried fruits and 5 other foods. Spices, herbs and semi-dried foods demonstrated the highest bacterial and fungal loads with the majority showing over 10 4 CFU/mL. Nuts and other foods showed growths ranging from 10 2 to 10 6 CFU/mL. The current study also attempted to determine the effects of heat and plasma treatment. The log reduction of bacterial growth after heat treatment maximum: 120 min for 60 was between 0.08 to 4.47, and the log reduction after plasma treatment maximum: 40 min ranged from 2.37 to 5.75. Spices showed the lowest rates of reduction, whereas the semi-dried and other foods showed moderate to high levels of decrease after heat treatment. The log reduction of fungal growth after heat treatment ranged from 0.27 to 4.40, and log reduction after plasma treatment ranged from 2.15 to 5.91 Furthermore, we validated the sterilization effect of plasma treatment against Bacillus spp. and Staphylococcus spp. by using scanning electron microscopy. Both treatment methods could prove to be advantageous in the agriculture related fields, enhancing the quality of the foods.Key words Bacterial counts of food / Fungal counts of food / Heat treatment on food / Low-pressure plasma treatment / Scanning electron microscopic study.

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This study was carried out to determine the contents of vitamins A and E in carcass fat from Japanese Black and F1 cross cattle, because the method of controlling the amount of vitamin A in feed has been used in the production of expensive beef with high marbling in Japan. We determined the contents of tocopherol and retinol in subcutaneous and perirenal fats for 40 carcasses of Japanese Black and F1 (Holstein×Japanese Black crossed) cattle that had been sent to market from 10 prefectures. In bovine fat, free αtocopherol was present in the greatest amount, the level of γ-tocopherol was about 10% and there was only a trace of δ-tocopherol. The means±standard deviation of α-tocopherol content in subcutaneous and perirenal fats were 0.68±0.33 mg/100 g and 0.54±0.23 mg/100 g, respectively. The means±standard deviation of retinol content in subcutaneous and perirenal fats were 2.9±4.5 µg/100 g and 2.9±5.1 µg/100 g, respectively. Both vitamins differed widely between animals and were present at a relatively low level compared to other reports (α-tocopherol 2.4-5.4 mg/100 g fat tissue and 30-220 µg/100 g muscle tissue). The correlation coefficients between subcutaneous and perirenal fats for retinol and α-tocopherol content were 0.97 (p<0.01) and 0.82 (p<0.01), respectively, which showed high correlation. However, the correlation coefficients between retinol and α-tocopherol contents for subcutaneous and perirenal fats were 0.11 and 0.08, respectively, which showed low correlation. Breed effect was observed in both vitamins. These results indicated that vitamins A and E in fat from Japanese Black and F1 cross cattle under the vitamin A controlling method are present at relatively low levels and feeds need to be supplemented with vitamin E.

Fat quality, in particular, firmness is a main contributor to meat appearance, shelf life, taste, and human health. The current study was conducted to examine the fluctuation and criteria of porcine fat firmness. Several physiochemical methods were performed on 237 porcine perirenal fat samples that were obtained randomly from a commercial market. The relationship between perirenal fat and the middle subcutaneous fat layer was investigated to predict carcass fat quality. Each physiochemical property of the perirenal fat showed considerable variation as a 40-fold difference in firmness was observed between the most extreme samples. Differences between these extremes were 19°C in melting point, 0·0043 for refractive index, and 18 g per 100 g fatty acid methyl esters for saturated fatty acids (SFA) concentration. Strong curvilinear relationships were found between Instron and sensory firmness scores (R=0·90–0·96, no.=24). On the basis of these relationships, classification of the perirenal fats obtained from the commercial market was defined. Fats possessing firmness values of less than 7 N have undesirable fat quality, whereas fat samples with values greater than 16 N were not popular in the market. From these data, we conclude that fats of 7–16 N in firmness value were preferred by consumers. Firmness values of perirenal fat samples correlated significantly with the stearic acid (C18:0) and SFA concentrations of samples of the middle subcutaneous fat layer (r=0·68, 0·57, P<0·01). These results indicate that there are wide fluctuations in the porcine fat quality, and that fats ranging in Instron firmness values between 7 and 16 N are most acceptable to consumers. And, subcutaneous fat may prove to be a valuable indicator of whole body pork fat quality.