Rice Utilization and Product
Development-78
 
 

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Project Leader and Principal Investigators

R.M. Saunders, USDA

D.A. Fellers

R.L. Roberts

A.E.Deissinger

A.P. Mossman

M.M. Bean

K. Nishita

B.S. Luh, UC Davis

D. Wong

I. Nayaga

E.E. Zalaki

M. Ejlali

 

Objective

Increase the demand for and use of California rice through development of new rice products and improved cooking performance.

Effect of milling on the nutritive value of rice:

"A technique for processing a quick-cooking brown rice has been developed and successfully tested on Calrose and Colusa brown rice."

The effect of milling on calcium, potassium, sodium, and microelements such as copper, iron, manganese, and zinc in three new California-grown rice varieties (Terso, M5 and S6) showed that these elements decreased slightly with milling and decreased sharply when the grain was polished. The bran fraction was a good source of mineral elements, rice oil, and protein.

The minerals present in well-milled rice in descending order of concentration were: phosphorus, potassium, calcium, sodium, iron, manganese, zinc and copper. No cadmium was found in any of the samples.

Cooking experiments with four varieties of rice-S6 (short grain), M5 (medium grain), 72-Y-54 (medium grain), and 72-3764 (long grain)indicate that varietal characteristics and the water/rice ratio during cooking influence the firmness and stickiness of the cooked rice.

Cooking characteristics of rice:

Optimum texture was obtained when the water/rice ratio was between 1.15 and 1.20. As the water/rice ratio increased, firmness of the cooked rice decreased and stickiness increased because of the gelatinization and hydration of the starch in the rice. Also, milled rice with higher amylose content had a firmer texture than that with lower amylose. The amylose content of the medium- and short-grain rice varied from 19 to 24 percent while that of the long-grain rice was 27.8 percent on a dry basis.

A long-grain rice, 72-3764, appears very desirable because of its fine cooking qualities, and it is currently in limited use.

Storage stability of quick-cooking rice

Storage experiments with quick-cooking samples of short-grain California pearl, medium-grain Calrose, and long-grain Arkansas Starbonnet rice show that storage temperature influences coloration of the product. Samples stored at 100 degrees Farenheit rapidly turned brown while samples stored at 70 degrees and 35 degrees satisfactorily retained their natural color during a 12-month storage period. Therefore, storage temperatures between 35 and 70 degrees appear best for retaining quality in quick-cooking rice.

Development of a quick-cooking brown rice

A technique for processing a quick-cooking brown rice has been developed and successfully tested on Calrose and Colusa brown rice. The resulting product can be cooked in one-quarter of the time normally required for raw brown rice. Its protein, vitamin, and mineral contents are comparable to raw brown rice and higher than those for white rice.

Development of a rice-soy-milk product

"A product that uses precooked and reground rice brokens, toasted defatted soy flour, and non-fat dry milk as the main ingredients has been formulated."

A product that uses precooked and reground rice brokens, toasted defatted soy flour, and non-fat dry milk as the main ingredients has been formulated. Also, a computer program has been developed to predict protein quantity and quality and cost of the product as ratio and costs of the major ingredients vary.

Conversion of waste rice straw into sugar syrup and yeast protein

Yeast single-cell protein was successfully produced on straw breakdown products during fermentation. The yeast contained 50 percent protein that had an amino acid content comparable to yeast grown on a synthetic medium, except for a lower level of arginine. Nutritional value of the yeast was similar to that of control protein sources when fed at low levels, but it did not perform as well when fed as the sole source of protein.

The optimum level of straw utilization was 75 percent-25 grams of glucose were enzymatically produced from every 100 grams of rice straw hydrolyzed.

There was no detectable mutagenic (potentially carcenogenic) activity in extracts of the yeast, sugar syrup, or byproducts produced. But, at least one pesticide used on rice, parathion, can be picked up by the yeast protein from the sugar solution. The pesticide can be broken down by pretreating the rice straw with hot alkali prior to hydrolysis. Studies with other pesticides -MCPA, carbofuran, and molinate-are in progress.

 

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