The physicochemical properties of rice flour produced by 3 different grinding methods using various steeping times (3, 6, 9, and 12 hrs) were investigated. Roller mill gave coarse rice flour; the pin mill, intermediate flour; and mixed when both (roller & pin mills) were used. With the increase of steeping times, the rice flours became finer and the contents of crude protein, crude fat and crude ash decreased. Damaged starch was noticeably high in rice flour by roller & pin mills compared to those by roller or pin mills alone. Amylose contents, solubility and swelling power increased as the steeping times increased. Water binding capacity was the highest in roller & pin mills, followed by pin mill. In scanning electron microscope (SEM), pin mill showed distribution of separated fine particles of rice flours. The physicochemical properties of rice flours showed many differences by steeping times of rice and grinding methods. With sufficient steeping times, the rice flours obtained from pin mill were relatively fine having less damaged starch.

http://koreascience.or.kr:80/article/JAKO200925836515035.pdf

제분방법 및 수침시간을 달리한 멥쌀가루의 이화학적 특성

멥쌀을 4℃에서 수침시간을 달리하여 수침하고 건조, 분쇄하여 각각 표준 45 mesh와 100 mesh제를 통과시켜 IL45(<355μm)와 IL100(<150μm)을 제조하여 일반성분과 이화학적 성질을 조사하였다. 멥쌀을 4℃에서 24시간 동안 수침하였을 때, 수침 0.5시간까지는 급속히 수분이 흡수되었으며 수침 3시간 이후에는 평형에 도달하였다. IL45와 IL100 모두 <40μm와40-100μm의 두 가지 크기의 쌀가루 입자가 존재하였다. IL45에 비하여 IL100의 입자 크기가 더 작았으며 수침시간이 증가할 수록 크기가 작은 입자의 양이 약간 증가하는 경향을 보였다. 시료의 단백질과 회분함량은 수침시간이 증가할수록 감소하였다. 아밀로오스 함량은 수침시간이 길어질수록 증가하는 경향을 보였으며, 입자의 크기에 따른 차이는 없었다. 멥쌀가루의 물결합 능력은 수침시간이 증가할수록, 입자의 크기가 작을수록 증가하였다. 팽윤력과 용해도는 65℃ 이후에 급격히 증가하여 85℃부터는 완만한 증가를 보였으며, 수침시간이 길어지고 입자의 크기가 작을수록 증가하였다. 신속점도측정기에 의한 최고점도와 breakdown 값은 12시간 동안 수침한 쌀가루가 1시간 동안 수침한 쌀가루보다 높았으며, 95℃에서의 점도, 냉각점도와 setback 값은 낮았다. X선 회절도 결과 모든 시료가 전형적인 A-형이었으며 입자크기와 수침시간에 따른 차이가 없었다. SEM으로 배율을 달리하여 멥쌀가루의 입자와 입자표면을 관찰하였을 때, IL45보다 IL100에서 작은 입자가 더 많이 관찰되었고 수침시간이 길어질수록 표면에 결합된 전분입자의 수가 감소하였다. 또한 쌀가루 입자 표면에 작은 균열들이 관찰되었고 표면에 변화가 나타나는 전분입자의 수가 증가하였다. 이상의 결과에서 쌀의 수침 중 수분 흡수량이 평형에 도달한 이후에도 쌀 입자표면의 변화나 전분의 구조적 변화가 진행되어 쌀가루의 이화학적 성질에 영향을 주게 되므로 쌀 가공식품을 제조하기 위하여 쌀을 수침하였을 때 수분 흡수량보다는 수침시간과 온도 조절이 더 중요한 것으로 생각되었다.

수침시간과 입자크기가 다른 멥쌀가루의 특성

To increase rice consumption and substitute rice flour for wheat flour to make gluten-free bakery products, the physicochemical and pasting properties of rice flours prepared from raw and soaked rices passed through different size screens were investigated. The quality properties of manju dough and preparation of rice manju were also measured. Dry milled flour with soaked rice (DMFSR) were decreased in ash and crude lipid contents compared to dry milled flour with raw rice (DMFRR). Water binding capacity, damaged starch content, and L value of rice flour increased with decreasing particle size, but the b value decreased. Peak, cold, and breakdown viscosities of DMFSR were higher than those of DMFRR by RVA. Hardness of manju dough with DMFSR was lower than that with DMFRR, but that of manju shell exhibited a reverse trend. Sensory difference testing revealed the smoothness of surface, hardness, roughness, and overall quality were significantly different (p<0.05). The smoothness of the surface of manju with DMFRR-200 and all DMFSR were better than that of manju prepared with wheat flour. Hardness showed lower values in DMFRR-200, and all DMFSR as well as wheat flour and roughness decreased with decreasing particle size. Rice manju with wheat flour, DMFRR-200, DMFSR-120, and DMFSR-170 ranked above 5 points and were not significantly different (p<0.05).

Characteristics of Preparation of Rice Manju and Rice Flour with Soaking and Different Particle Sizes

Background: The Korean government launched a project in 2008, where the am ount of rice used as raw ingredient in rice-based foods in 2012 was planned to increase up to 10% (470,000 ton) of the total rice production through developing various new rice-based processed foods and their commercial manufacturing technology. Among the four major rice-based processed foods, rice cakes and noodles need rice flour as their main raw ingredient. Technology in rice flour utilization and manufacturing is far behind than the technology pertinent to wheat flour in many subject areas. Purpose: This review aims to provide information on rice flour utilization and manufacturing with some fundamental subjects in the area of size reduction. Results: A variety of food items including bread, noodle, cake, cookie, muffin, pre-mix, beverage, vinegar, surimi, and artificial meat have found rice flour as their raw ingredient. Rice bread made out of 100% rice flour has been developed and is now sold in retail stores. Various noodle products made from rice flour are also on the market. Issues on product definition and labeling regulation about rice flour content of the products were explored. Generalized grinding equations available in the literature were seldom used in practice; inste ad, it has been a general practice to develop empirical equations from test milling data. Introductory remarks on three popular particle size measurement methods (sieving, Coulter counter, light diffraction) were explained. Mathematical expressions frequently used to describe particle size distribution and to correlate cumulative quantity of particles with particle size were represented. Milling methods used in producing rice flour were described along with their advantages and disadvantages. Because of their profound effect on functional properties of the rice flour, four rice flour milling equipments used at both laboratory experiments and commercial manufacturing plants were discussed.

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Review on Rice Flour Manufacturing and Utilization

pasting characteristics. Their water contents, water holding capacities, solubilities, swelling power, amylose contents, damaged starches, particle sizes and pasting characteristics were measured. The water content and water holding capacities of various types of rice flours collected in the market were 7.64-14.97% and 95.22-232.94%, respectively. Their solubilities and swelling power were 1.97-37.40% and 1.33-5.76, respectively. Various types of rice flour had 32.11-305.67 particle sizes. Among the various types of rice flour collected in the market, the lowest starch damaged content was 3.17%. The peak viscosities of the samples were 17.74-295.95 RVA. Among the rice flours that were collected in the market, the lowest pasting temperature was . As a result, it was shown that rice flour types with high starch damage contents tend to have higher expressed water holding capacities. Moreover, the samples with lower particle sizes tended to have final viscosities, and pasting temperatures.

Starch and Pasting Characteristics of Various Rice Flour Collected from Markets

Two different methods (Sieve shaker, Elzone particle size analyzer) were used to investigate rice flour particle size obtained by various milling method. Results of Elzone particle size analyzer were more effective than Sieve shaker in determining particle size, and the distribution of particle size of rice flours was affected by the type of the milling methods used. A rice flour, prepared in a Pin mill had a particle size range of mesh, and 30.38% of the sample was in the particle size range mesh. A rice flour, prepared in a Colloid mill had a particle size range of mesh and more of flour particles appeared in the range mesh than any other particle size. A rice flour, prepared in a Micro mill had a particle size range of mesh, and 41.62% of the sample was in the particle size range over 500 mesh. A rife flour, prepared in a Jet mill had a finer flour particle size was over the particle size range 500 mesh. The finer rice flour gave the highest L value and the lowest a value. The wet-milled flour particles were observed as a cluster of starch granules and the particles of rice flour (dry-milling) were observed as fragment of rice grains. Scanning Electron Photomicrographs revealed that visual differences in structure between milling methods, and similar results with Elzone particle size analyzer method in particle size.

https://koreascience.or.kr:443/article/JAKO199303041996495.pdf

Effect of Different Milling Methods on Distribution of Particle Size of Rice Flours

The relative retrogradation of Jeungpyun investigated with different milling methods of rice flour. The relative retrogradation of Jeungpyun was reduced in order that of W-C, W-P, D-M, D-J in DSC(Differential Scanning Calorimetry) method while W-C, D-M, D-J, W-P in Diastase method. In wet milling method, the relative retrogradation of Jeungpyun by pin mill (W-P) was lower than Jeungpyun by colloid mill (W-C). In dry milling method, the relative retrogration of Jeungpyun by jet mill (D-J) was lower than Jeungpyun by micro mill(D-M). The relative retrogradation of Jeungpyun by DSC method was similar to the diastase method. The relative retrogradation of Jeungpyun was decreased with decreasing particle size and setback value for amylogram and increasing damaged starch.

Young-In Kim

Papers

Effect of Different Milling Methods on Distribution of Particle Size of Rice Flours

Retrogradation characteristics of Jeungpyun by different milling method of rice flour