Effect of multi-step soaking process on head rice yield of parboiled paddy

Document Type : Research Paper


Department of Biosystems Engineering, School of Agriculture, Shiraz University, Shiraz, I. R. Iran


Parboiling is one of the postharvest hydrothermal treatments applied on rough rice before drying and milling processes. This process has an important role in retaining the quality of rice kernels during storage, milling, and cooking. In this study, two rough rice cultivars, Tarom and Fuji Minory, were subjected to conventional and multi-step soaking for 90 minutes in water at temperatures of 50, 60 and 70 °C as a part of the parboiling process. Multi-step soaking was conducted in two and three steps followed by 15 minutes steaming at atmospheric pressure. Drying was performed by a fixed bed hot air dryer at 35 °C. The results indicated that in the conventional soaking, soaking temperature and steaming time affected the percentage of broken rice, bending strength and head rice yield (HRY) for both cultivars in a significant manner (P<0.05). The effect of soaking steps and steaming duration on the percentage of broken rice, bending strength, and HRY at temperature 70 °C were significant (P<0.05) for both rice cultivars. In overall, the multi-step soaking showed a significant positive impact on measured traits as compared to conventional soaking.


Article Title [فارسی]

اثر فرآیند خیساندن چند مرحله‌ای بر عملکرد برنج سالم شلتوک نیم پخت شده

Authors [فارسی]

  • ناصر رضوی زاده
  • سید مهدی نصیری
  • داریوش زارع
بخش مهندسی بیوسیستم، دانشکده کشاورزی، دانشگاه شیراز، شیراز، ج. ا. ایران
Abstract [فارسی]

نیم‌پخت کردن برنج یک از عملیات آبی-حرارتی شلتوک پیش از فرآیند‌های خشک­کردن و پوست­کنی شلتوک است.. این عملیات نقش موثری در افزایش کیفیت دانه برنج هنگام ذخیره کردن، آسیاب کردن و پختن دارد. در این مطالعه برای انجام فرآیند نیم‌پخت کردن، از دو رقم شلتوک طارم و فوجی‌مینوری برای خیساندن معمولی و چندمرحله‌ای (پلکانی) به مدت 90 دقیقه در آب با دماهای 50، 60 و 70 درجه سلسیوس استفاده شد. خیساندن چندمرحله‌ای در دو و سه مرحله انجام شد و سپس نمونه‌ها به مدت 15 دقیقه در فشار اتمسفر بخاردهی شدند. خشک کردن با استفاده از خشک‌کن هوای گرم با بستر ثابت با دمای 35 درجه سلسیوس صورت گرفت. نتایج نشان داد در خیساندن به روش معمولی، اثر عامل‌های اصلی شامل دمای خیساندن و مدت زمان بخاردهی بر درصد ترک، استحکام خمشی و عملکرد برنج سالم هر دو رقم معنادار (0/05>P) بود. تاثیر مراحل خیساندن و مدت زمان بخاردهی بر درصد ترک، استحکام خمشی و عملکرد برنج سالم در دمای 70 درجه سلسیوس در هر دو رقم معنادار بود. به‌طور کلی خیساندن چندمرحله‌ای در مقایسه با خیساندن معمولی تاثیر مثبت قابل توجهی بر صفات اندازه‌گیری شده داشت.

Keywords [فارسی]

  • عملکرد برنج سالم
  • خیساندن چند مرحله‌ای
  • نیم‌پخت کردن
  • درصد ترک برنج
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