Heat treatment of high moisture paddy for temporary storage | |
| Author | Reyes, Vicente Geronimo |
| Call Number | AIT Diss. no.AE-86-02 |
| Subject(s) | Rice--Storage Rice--Drying |
| Note | A dissertation submitted inpartial fulfillment of the requirements for the degree of Doctor of Engineering, School of Environment, Resources and Developmemt |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. AE-86-02 |
| Abstract | A study of thermal inactivation of molds in freshly harvested high moisture paddy (RD—23 variety) was carried out using a batch—type experimental heating unit. Heating surface temperatures ranging from 75 to 200 °C and exposure times upto 100 minutes were used. Quality—effects of heat treatments on high moisture paddy were investigated in terms of moisture removal, head rice yield, milled rice Finally, safe holding periods evaluated based on a reduction in the discolored kernels. Heat treatments reduced whiteness and cooked rice texture. of heat—treated paddy samples were in head rice yield and an increase the fungal growth and hence the spoilage in newly—harvested high moisture paddy leading to its safe temporary storage. The fungal mortality levels close to 90% or slightly higher appeared to be satisfactory for general use. For 90% fungal mortality level, the equivalent exposure times (F-values) were determined to be 22, 43 and 84 minutes at selected bulk grain temperatures of 70, 60 and 50 °C, respectively without any consideration of heating lags. A general procedure was developed for estimating the heating times based on the time- temperature history of high moisture paddy in a given heating system in order to reduce the fungal activity to a desired level. Heat treated paddy samples showed an increase in head rice yield first and a subsequent reduction depending upon the heating surface temperature, exposure time, and initial moisture content. Optimum time—temperature combinations for obtaining maximum head rice yield were established for general use. Heat treatment of paddy with initial moisture content in the range of 22 to 26% w.b. using optimum heating times resulted in 14 to 25% increase in head rice yield, final moisture content of 18 to 19%, and fungal mortality level of about 90 to 95%. These results indicated the need for an alternate second—stage drying procedure to bring the moisture content down to safe storage level. paddy resulted days based on kernels in the safe holding based on the In general, heat treatment of high moisture in increased safe holding periods of about 9 to 20 an acceptable limit of 1.5% increase in discolored milled rice. A relationship for estimating the periods of freshly—harvested paddy was developed moisture content and the fungal mortality level at the beginning of storage. A comparison of computed and experimental safe storage periods determined with a full—scale prototype rotary heater showed a reasonable agreement and thus validated the general applicability of the proposed heat treatment procedure. |
| Year | 1986 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. AE-86-02 |
| Type | Dissertation |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Agricultural and Food Engineering (AE) |
| Chairperson(s) | Jindal, V. K.; |
| Examination Committee(s) | Exell, R. H. B.;Gupta, C. P.;Ilangantileke;Chongrak Polprasert; |
| Scholarship Donor(s) | Government of Japan; |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 1986 |