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Low-temperature aging and drying treatments of restorative rice to improve its microbial safety and texture

복원용 밥의 미생물 안전성 및 식감 향상을 위한 저온 숙성 및 건조 처리

  • Received : 2018.10.28
  • Accepted : 2019.01.22
  • Published : 2019.02.28

Abstract

In this study, a commercial production stepwise method for restorative rice with high quality and microbial safety was developed. The stepwise treatment method included steaming, refrigerated aging, and low temperature drying. The soaking rice was steamed twice at $90-100^{\circ}C$, and then, the rice was aged at $0-10^{\circ}C$, frozen at $-20^{\circ}C$, and dried at low temperatures with 5 m/s wind speed at $1-20^{\circ}C$ and 85% relative humidity. Applying the three steps improved sensory qualities compared with the conventional hot air drying and made storage at room temperature for 3 months possible. Specifically, the moisture content of the restorative rice was increased to 30%, which was 4.3 times higher than the 7% of the conventional air dried rice, and the rice grain shape was well maintained. The texture and appearance of the three-step rice were significantly improved (p<0.05) in a sensory evaluation.

Keywords

restorative rice;steaming;refrigerated aging;freezing;low temperature drying

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Fig. 1. The diagram of treatment processing of conventional and improved restorative rice.

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Fig. 2. The comparison of appearance and shape between conventional restorative rice by hot air drying and improved restorative rice by combination of refrigerated aging and lowtemperature drying treatment.

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Fig. 3. The improvement effect on sensory evaluation of restorative rice by combination of refrigerated aging at 20oC, 4 h and low temperature drying treatment at 20oC, 5 h (Water content 10, 20, 30, 40%).

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Fig. 4. The comparison of appearance and shape after restoration from hot water between conventional restorative rice by hot air drying and improved restorative rice by combination of refrigerated aging and low temperature drying treatment.

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Fig. 5. The improvement effect on sensory evaluation of restorative rice by combination of refrigerated aging and low temperature drying treatment.

Table 1. Microbial safety and organoleptic quality per storage period of improved restorative rice by combination of refrigerated aging at 20oC, 4 h and low temperature drying at 20oC, 5 h

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