A sound understanding of rice starch characteristics—such as gelatinization temperature, gel viscosity, and related properties—is essential to precisely define parboiling process parameters and achieve the desired end-product physiology.
Between 1993 and 1995, significant efforts were undertaken by United Riceland Ltd. to transition from conventional parboiling practices to a mechanized, system-based process. This shift greatly improved hygiene, consistency, and reliability of the finished product. During this period, I closely assisted Rice Chemist Dr. K. R. Bhattacharya, and the journey involved intense experimentation, learning, and perseverance.
Beyond soaking and steaming, drying of parboiled paddy presents its own unique challenges, particularly for both Basmati and non-Basmati varieties. Based on the fundamental principle that evaporation causes cooling, the initial drying phase of parboiled paddy can reduce moisture content from 37% to 22% using air temperatures of 250°C or even 300°C.
My initial pilot-scale trials with Vibro Fluidized Drying revealed that Basmati rice—owing to its slenderness ratio of over four—was not a suitable candidate for this method due to multiple technical limitations. In contrast, the Tunnel Dryer project that followed proved far more effective and exciting. With a residence time of less than 15 minutes, paddy moisture was successfully reduced from 37% to 22% without any adverse side effects. This development offers a significant advantage to millers seeking consistent product quality and dependable milling yields.
Regarding soaking and steaming, numerous permutations and combinations are available to achieve the desired cooking quality and appearance of raw rice. However, today’s evolving industry dynamics demand that millers move beyond traditional comfort zones.
Rising constraints related to land availability, manpower, and operational costs are driving the adoption of more efficient technologies—such as pressure soaking, pressure steaming, and fast drying systems. Additionally, utilizing steam generated from husk-fired power plants in back-pressure mode can further enhance profitability.
In conclusion, millers and equipment suppliers alike must embrace modern parboiling technologies. The new methods discussed in this chapter of Rice Technology are not just innovations—they are necessities for sustainable, efficient, and competitive rice milling in the years ahead.