Bacterial persister cells are metabolically dormant cells in which cell activities such as protein synthesis and cell division are somehow drastically slowed down, so that they can survive under intensive antibiotic treatment that targets such cell activities. This review summarizes information about persister cells such as their history, definition, mechanism of formation, threats to clinical environments, and how to control them. In addition to such information, this review also introduces our recent studies on the physical stress tolerance of persister cells and their possible control in food environments. We demonstrated that some bacterial persister cells are indeed highly heat and acid tolerant compared to normal cells, although diversity was discovered in persister cell populations. We also found that indole and its derivatives or acetic acid are promising candidates for persister cell eradication in food environments. We believe that this review will aid in wider attention to and understanding of the importance of these quiet yet clever bacterial persister cells.
Through the use of vacuum packaging and high-pressure thermal processing, we have developed REAFRU, a processed fruit product that can be stored at room temperature, has no additives, retains the taste and aroma of fresh fruit, and has an excellent appearance. REAFRU production consists of peeling, cutting, vacuum packaging and high-pressure thermal processing with a retort sterilizer. Setting the degree of vacuum packaging as 99 % or higher is necessary. A heating temperature of 100 ℃ for 10 minutes is appropriate. To prevent discoloration after processing, the gas barrier performance of the pouch is important and a very low oxygen transmission rate is required. The technology for production of REAFRU has been shared with five companies in Hokkaido, and the products are sold for general and business use, and the production volume is steadily increasing.
There has been growing interest in inside-outside beauty products. Companies in Fukuoka Prefecture were not able to develop such products as expected because of the lack of collaboration with skin health research experts. The diverse and complex needs of the companies did not closely match the specific materials or technologies developed by public research or other institutions. In this work, we describe the support system we have established for the development of functional food and cosmetic products. The system consists of a series of technologies such as the extraction, analysis, isolation, identification, concentration and enrichment of bioactive compounds; the functional analysis of food materials, with special focus on skin care function; and drying and powdering. Thirty-eight products have been successfully released by the companies through the application of this system. In conclusion, the support system we established was considered useful to promote the development of functional food and cosmetic products in Fukuoka.
We established several study groups with members such as private companies and government agencies. The activities of these study groups are collaboration for the exchange of information, development of new technologies and products, and sales promotions at related events. Herein, I will introduce the study group activities for research support for Akamoku (called Gibasa in Akita Prefecture) and Jerusalem artichokes. Specifically, we researched the differences in characteristics of these local products made in Akita Prefecture. In the Akamoku study group of Akita Prefecture, a salient feature was that the relative viscosity varied depending on the manufacturing region. In addition, the relative viscosity and fucoxanthin content—reported to have an antiobesity effect—were found to differ according to cultivation area, crop time, and sex. In the Jerusalem artichoke study group of Akita Prefecture, a salient feature was that the inulin sugar degree of polymerization was low in the domestic Jerusalem artichoke and it was the chief ingredient in the Akita Prefecture product. The free sugar and fructooligosaccharide content were found to vary according to cultivation area, cultivation technique, and cultivation year. These tendencies were also recognized for free amino acids, particularly Arg.
和牛肉 (黒毛和種, A4等級) の品質に及ぼす冷蔵の影響を明らかにするため, 種々の期間, 真空包装で冷蔵 (2 ℃) したリブロースの品質評価および細菌検査を行った. と畜後, 10日冷蔵した牛肉を基準とし, 最大45日まで試験を行ったところ, 牛肉中の一般成分および脂肪酸組成には変化がみられなかったが, 遊離グルタミン酸量は, 冷蔵25日以降に有意な増加がみられた. また, この傾向は総遊離アミノ酸とも対応していた. 一方, 牛肉中のIMPは, 冷蔵期間が長くなるにつれて減少し, 25日目にIMPが有意に減少した. また, 牛肉の破断応力およびpHは冷蔵45日目で有意な減少がみられ, グルコースおよび乳酸量は増加した.
牛肉の乳酸菌数は冷蔵35日目に増加し, 一般生菌数も45日目に増加がみられた. 大腸菌, 黄色ブドウ球菌およびサルモネラ菌は, 冷蔵期間中に検出されなかった.
In order to prevent the decline of Japanese agriculture, forestry, fishery, and food industries as well as to promote their sustainable development, it is essential to capture growing overseas markets through export promotion and overseas expansion efforts. In this presentation, I will explain the policies for facilitating the export of Japanese agricultural, forest, and fish products and food, with the aim of achieving the export value targets of 2 trillion yen in 2025 and 5 trillion yen in 2030.
Freezing wheat dough has great benefits in reducing baking costs and time, but bread baked from frozen dough has a smaller loaf, coarser crumb, and harder crust than bread baked from fresh dough. In addition to the preservation process, the ingredients added to frozen dough have a substantial positive impact on the quality of frozen dough. In this study, the effects of the addition of oil on the physical properties of frozen dough and the quality of the bread baked after freezing and thawing were examined. Quality change was investigated for four types of frozen dough made from four different fats with different triacylglycerol constituent fatty acids. Frozen dough with added soybean oil and grapeseed oil had a thicker crumb skeleton after baking. In addition, the frozen dough with soybean oil showed less stretchiness and more protein conglutination. The ratio of unsaturated fatty acids in the oil tended to adjust the extensibility of the frozen dough and alter the crumb skeleton of the baked bread.