Bogim Gil

Comparative study of soybean oil refining using rice hull silicate and commercial adsorbents

To obtain an edible grade of soybean oil, impurity removal processes are important steps in refining. To remove coloring compounds and free fatty acids, commercial adsorbents (silica gel, activated carbon, aluminum oxide, alumina silicate, acid clay, and zeolite) and rice hull silicate (RHS) were evaluated with respect to their adsorption removal efficiencies for lutein. Various doses of commercial adsorbents and RHS were individually added to degummed soybean oil to remove lutein. The commercial adsorbents and RHS substantially reduced lutein amounts in degummed soybean oil. Silica gel was the most effective adsorbent, followed by acid clay, and RHS. Treatments with adsorbents also reduced the residual free fatty acid (FFA) content. Aluminum oxide was the most effective in removal of FFA (approximately 40% reduction). RHS and rice hull ash (RHA) showed similar deacidification effects. RHS can be used as an alternative bleaching agent as it was effective in reducing the residual FFA content in soybean oil.

Enrichment of Phenolics in Harvested Strawberries by High-Pressure Treatment

In order to investigate the effect of a high-pressure (HP) treatment on enrichment of phenolics in harvested fresh strawberries, the total phenolic (TP) and anthocyanin (TA) contents were measured by colorimetry and the concentrations of ten individual phenolic compounds were analyzed by HPLC. While there were few changes in the physiochemical properties of strawberries, the contents of TP, (+)-catechin, p-hydroxybenzoic acid, and pelargonidin-3-O-glucoside were enriched at the 5% level of significance.

A Quantified Index for Rapid Evaluation of Starch Content in Apples

Starch content in apples is being used as an indicator of maturation because there is a close relationship between them. However, a chemical and analytical assessment is very timeconsuming. In this study, a rapid method to evaluate starch content in apples was investigated, which had procedures to stain an apple slice with an iodine solution and analyze the stained color image. First, a ratio of the stained area to the whole area of an apple slice was defined as a starch index. Because starch in apples is composed of amylose and amylopectin and each component had a unique color after staining with an iodine solution, 3 different thresholds to recognize the stained area were introduced: starch index 1 processed by the threshold of pure blue in HLS color system, starch index 2 by that equivalent to 5.8 PB in Munsell color system, and starch index 3 by that of average gray intensity of b frame in standardized rgb color system. When all the starch indices were related to a chemistry-based starch assessment, a correlation coefficient of starch index 1 with starch content including both amylose and amylopectin was 0.811 compared to that with amylose content was 0.633. Introduction Starch in apples is closely related to their maturation and ripening. That is, the breakdown of starch to soluble sugars such as glucose, fructose or sucrose is a characteristic maturation and ripening event [1, 2]. The optimum time for harvest of apples can be determined by evaluation of starch content which designates their maturity. Also, during ripening of harvested apples containing an amount of starch, its degradation occurs and has an effect on the taste. This feature in the aspect of quality needs evaluation of starch content of apples. Chemical titration method to determine the starch content is hardly used in the production and handling sites of fruits for their quality evaluation because it is difficult and time-consuming. Instead, starch in a plant tissue has been stained with an iodine solution in the aspect of its qualitative evaluation. Particularly, the starch-iodine test is being widely used as a simple index which provides an estimate of relative apple starch content. Apple starch consisted of two components, or amylose and amylopectin [3,4]. Cho et al. [4] reported that the amylose contents in Fuji apples were 44.0 to 55.4% of the total starch contents. Both components form a polyiodine complex with an I2-KI solution, showing blue color. Specifically, the amlyose-polyiodine complex produces a dark blue pigment, while the amylopectin-polyiodine complex develops a light purple-red pigment. Morrison and Karkalas [5] reported that the binding capacity of amylose with I2 was 20 to 21 g per 100 g, whereas that of amylopectin was 0.3 to 2.6 g per 100 g. The maximum absorbance is between 630 to 680 nm for the amylose-polyiodine complex and 530 to 585 nm for the amylopectin-polyiodine complex, depending on analytical conditions. In general, the stained degree with respect to starch content is being rated with a unaided eye. Fan et al. [3] evaluated the stained degree visually and rated starch index using a 1 to 6 scale (1 = 100% stained, full starch; 2 = clear to core line; 3 = 50% cortex and core area clear; 4 = 75% cortex 1 Corresponding author: Yong-Jin Cho, Ph.D., Principal Researcher, Korea Food Research Institute, San 46-1, Baekhyun-dong, Songnam 463-746, Korea. (phone) 031-780-9136, (fax) 031-780-9228, (e-mail) yjcho@kfri.re.kr Key Engineering Materials Online: 2004-08-15 ISSN: 1662-9795, Vols. 270-273, pp 1032-1037 doi:10.4028/www.scientific.net/KEM.270-273.1032