Korean Journal of Food Science and Technology (한국식품과학회지)

Korean Society of Food Science and Technology (한국식품과학회)
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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

  • 천희순 (서울향료(주) 기술연구소) ;
  • 조원일 (씨제이제일제당(주) 식품연구소) ;
  • 정명수 (이화여자대학교 식품공학과) ;
  • 최준봉 (수원대학교 호텔관광대학원)
  • Received : 2018.10.28
  • Accepted : 2019.01.22
  • Published : 2019.02.28
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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.

본 연구의 침지쌀을 $90-100^{\circ}C$의 온도에서 1, 2차 증숙한 다음 $0-10^{\circ}C$의 냉장저온에서 숙성하는 1단계 처리와 이어 상대습도 85%, $-20^{\circ}C$에서 냉동하는 2단계 그리고 $1-20^{\circ}C$의 상압에서 5 m/s 풍속으로 저온 건조하는 3단계로 구성된 최종 수분함량 30% 인복원용 밥의 제조방법은 기존 열풍건조 대비 관능품질을 향상시키고 상온 3개월 내외의 보관을 가능하게 하였다. 구체적인 효과는 2단계 증숙 및 저온 장시간 건조 과정을 통해 개선된 복원용 밥의 수분함량이 기존 건조밥의 7% 대비 4.3배 높고 쌀알의 고유 형태가 잘 유지되어 있어 취식을 위한 열수 복원시 전반맛, 식감과 외관이 관능평가에서 통계적 유의 있게 향상되었다(p<0.05). 또한 수분 30% 수준은 최적의 관능품질을 나타내면서 미생물 생육을 저해하여 저장성을 향상시키는 조건으로 파악되었다. 이러한 품질 및 저장성 향상 효과가 있는 처리 방법을 멥쌀, 찹쌀, 밀, 콩, 메밀 및 보리 등의 다양한 곡물을 이용한 복원용 밥 제품의 제조에 적용할 수 있어 상업적 활용성이 매우 높다고 할 수 있다.

Keywords

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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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