| 研究課題/領域番号 |
15K07452
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| 研究機関 | 筑波大学 |
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研究代表者 |
Neves Marcos 筑波大学, 生命環境系, 准教授 (10597785)
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| 研究期間 (年度) |
2015-04-01 – 2018-03-31
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| キーワード | Food Egineering / lotus root / fresh-cut / stability |
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| 研究実績の概要 |
The overall purpose of this research is to enhance the storage stability of lotus root. In order to achieve this goal, in the second year of the project, on one hand we focused on the development of antimicrobial nanoemulsions, in preparation for the development of antimicrobial films foreseeing their usage as package for shipping fresh-cut lotus root to long distance. On the other hand, we are also looking into the development of technology for reducing the browning of fresh-cut lotus root upon storage, such as the effect of low pH treatment, and storage at reduced pressure.
We have investigated the antimicrobial activity of essential oil from Thymus capitatus, either in bulk form or encapsulated into Oil-in-Water nanoemulsions, and monitored their antimicrobial activity against Staphylococcus aureus, an undesirable food pathogen. The experimental results indicated that either bulk or nanoencapsulated T. capitatus essential oil was able to preserve the quality and enhance the shelf life of food products.
Moreover, we have also investigating about the effect of acidic treatment and packaging under reduced pressure on quality parameters of fresh-cut lotus root. For this purpose, we are monitoring the changes in color, texture, microstructure and enzymatic activity (polyphenol oxidase), during storage. The experimental results indicated that fresh-cut lotus root treated with citric acid aqueous solutions at different pH (ranging from pH 2 to pH 4), had the lowest change in color up to 8 days of storage under refrigeration, indicating reduced browning activity.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
Considering the major task planned for the second year (FY 2016) "Task 2: Development of edible coatings and nanocomposite films ", we purchased an automatic coating machine by gun spray jet (order-made, EP Tech., Hitachi) equipped with automatic temperature and jet strength controls, so that enabling the tuning of coating thickness in fresh-cut lotus root. For the moment, we are still testing different formulations of edible coatings.
Concerning of the effect of acidic treatment using citric acid solutions (pH 2 and 4) on the storage stability of fresh-cut lotus root, the experimental results indicated that the hardness of all samples decreased upon storage. However, visible decrease in hardness was observed in pH 2-treated samples. Based on the morphological analysis performed using scanning electron microscope, cell wall degradation was depicted in pH 2 and pH 4-treated samples during storage, which could possibly explain the tissue softening. In addition, results of the microbial analysis have shown that both pH 2 and pH 4 treatments reduced total Bacillus subtilis counts. In conclusion, lowering the pH of acidic treatments to pH 2 may be an effective strategy for improving the storage stability of fresh-cut lotus root.
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| 今後の研究の推進方策 |
In the third year of the project (FY2017), we will continue addressing "Task 2: Development of edible coatings and nanocomposite films". Regarding this task, the automatic coating machine equipped with gun spray jet will be used for coating fresh-cut lotus root slices with different thicknesses, foreseeing enhanced storage stability, as the enzymatic browning may be suppressed by the coating material. As for the coating materials, we are planning to include xanthan gum and guar gum, asides from the addition of a plasticizer such as glycerol, in the tests, and evaluate their effect in the final quality of fresh-cut lotus root.
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| 次年度使用額が生じた理由 |
In the initial research plan ,we had planned to purchase an automatic film casting machine, foreseeing its use in the development of package material for lotus root. As the project proceeded, some preliminary experimental results have indicated that coating may also be an effective alternative to suppress the enzymatic browning of lotus root, rather than developing nanocomposite films to be used as package material. In this regard, during the second year of the project we purchased an automatic coating machine equipped with gun spray jet and temperature control, which was cheaper than the initial budget forecast for purchasing the film casting equipment.
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| 次年度使用額の使用計画 |
In the third year of the project (FY2017), the additional budget will be applied on the purchase of various coating materials, for evaluation of their effectiveness while suppressing the enzymatic browning of fresh-cut lotus root slices.
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