| Rice is being used as staple food for more than half of world population.In the modern world,people prefer to eat processed food as compared to raw food because of its improved nutritional characteristics.Parboiling is one of the techniques to improve the rice nutritional value as well as other physicochemical properties.Parboiled rice has some advantages over raw rice;it has more resistance to spoilage and insects with more nutrients.Keeping in view these advantages,the pressure-parboiling method was selected to process to Japonica and Indica rice varieties.In the current study,different parboiling conditions were adopted to check the maximum variation resulted in the processing of rice.Meanwhile,drying of the food product,as well as parboiled rice,is a great challenge for industries.For this purpose,different drying methods were applied,and the energy consumption and quality of parboiled rice were evaluated.1.Two initial soaking temperatures(40 and 70)? for(30,90,and 180)min followed by steaming at elevated pressure 1 kg/cm2(121?)for 5,10,and 15 min were used to parboil paddy.The head rice yield(HRY),hardness,cooking time,water absorption,whiteness and color(b-value)were used as quality indicators in parboiling paddy.Furthermore,sensory analysis was performed to find optimum condition for both rice varieties and compared with their normal milled rice.It was observed that head rice yield was varied from 68.67%to 87.46%and 70.97%to 79.53%for 30 to 180 min soaking time at 40?soaking temperature,similarly,at 70? soaking temperature,it varied from 82.89%to 95.76%and 83.99%to 94.48%for 5-15 min steaming at 1 kg/cm2 pressure in Rong Youhua Zhan and Huaidao5 varieties respectively.Sensory analysis and other quality indicator showed that soaking at 70?for 180 min followed by 15 min steaming and 70?soaking for 90 min followed by 10 min steaming showed the best quality for Indica(RYZ)and Japonica(H5)rice varieties respectively.Moreover,Paddy treated at these conditions achieved the highest score in the sensory analysis by panelists.2.The effect of soaking temperature(29.77,40,55,70 and 80.23)?,soaking time(67.55,90,120,150 and 170.45)min and steaming time(1.59,5,10,15 and 18.41)min up to five levels on percentage head rice yield(HRY),hardness,cooking time,lightness and color was taken into consideration and the R2 values were 0.96,0.94,0.90,0.88 and 0.94 respectively.The head rice yield,harness,cooking time and color increased with the process severity and lightness decreased,but head rice yield increased up to some extent,then found been reduced.The predicted optimum soaking temperature,soaking time,and steaming time were 69.88?,150 and 6.73 min respectively,and predicted HRY,hardness,cooking time,lightness and color under this condition were 73.43%,29,95 N,32.14 min,83.03 and 12.24 respectively with composite desirability equal to 0.9658.The parboiling industry could use the finding of a current study to get the desired quality of parboiled rice.3.The two-stage drying process was applied with intervening rest time during parboiling of Indica rice variety(Rong Youhua Zhan).The effect of first stage temperature(FST),second stage temperature(SST),air velocity and rest time up to five levels on drying rate,energy consumption,head rice yield(HRY)and color of parboiled rice were studied.It was perceived,increasing FST,SST and air velocity negatively affected rice quality(head rice yield and color)whereas rest time influenced positively.The predicted optimal FST,SST,air velocity,and rest time were 83.61?,60?,2.50 m/s,and 90 min respectively,predicted drying rate,energy consumption,HRY,and color under this condition were 8.09%/h,12966 kJ/kg H2O,71.02%,and 14.75 respectively.The above optimal condition was predicted to enhance the rice quality under faster drying rate at minimum energy consumption.4.The effect of soaking temperature,soaking time,and steaming time on the degree of starch gelatinization,percentage head rice yield,hardness,lightness,and color of Japonica rice variety Huaidao5 were taken under consideration.The most appropriate model in the prediction of degree of starch gelatinization,head rice yield,hardness,lightness,and the color was quadratic with R2 values of 0.92,0.91,0.94,0.91,and 0.94 respectively by response surface method.Although,the degree of starch gelatinization,head rice yield,hardness,and color increased with the process severity thereby lightness decreased.However,HRY increased only up to some level before it started to reduce.The predicted optimum soaking temperature,soaking time and steaming time was 65?,135 min,and 10.66 min respectively and the predicted degree of starch gelatinization,head rice yield,hardness,lightness and color under this condition was 82.38%,73.44%,32.38 N,81.54,and 13.62 respectively.5.The effect of parboiling conditions(soaking temperature=65? for 6 h,steaming pressure=0.5,1.0,and 1.5 kg/cm2 for 5 min respectively)and comparison of three different drying methods two-stage drying(TSD),single-stage drying(SSD),and shade drying(SD)on rice quality were taken under evaluation.The parboiled rice was dried using laboratory drier at first stage temperature=90? and second stage temperature=50? during TSD with 120 min tempering,50? was used in SSD with an air velocity of 3.0 m/s respectively.Samples were dried at room temperature(25-30?,60±5%RH)for 2-3 days in case of SD.The results revealed that RYZ at P3 and H5 at P2 had given maximum HRY for all drying methods than other conditions,but SD was found more effective in HRY enhancement.The severity of parboiling condition increased the hardness and observed maximum at P3(44.65 N)in RYZ and P2(37.08 N)in H5 during SSD.The darkest color 20.79 and 22.63 found at P3 for both RYZ and H5 varieties during SSD respectively.The maximum cooking time(31.50 and 30.00)min at P3 and P2 recorded for cooking of parboiled RYZ and H5 rice varieties during SSD respectively.The maximum amylose content concentration was observed at P3 during TSD method,and other drying methods have less influence on it.In the current research,parboiling of Indica and Japonica rice was performed.Two rice cultivars RYZ and H5 were parboiled by various experimental treatments of soaking temperature,soaking time,steaming time,steaming pressure,and drying methods,the physicochemical characteristics such as HRY,hardness,cooking time,water absorption,whiteness,color,amylose content,starch gelatinization as well as drying rate and energy consumption were evaluated.Furthermore,various drying methods were used for parboiled rice dryings such as two-stage drying,single stage drying,and shade drying.The best method for parboiled rice drying was tried to investigate. |
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