Ultrasonic alkaline assisted extraction of protein from defatted rice bran and its properties and applications | |
| Author | Thutiyaporn Chittapalo |
| Call Number | AIT Diss. no.FB-10-01 |
| Subject(s) | Extraction (Chemistry) Rice bran |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Food Engineering and Bioprocess Technology, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. FB-10-01 |
| Abstract | Defatted rice bran (hexane free) composed of 11.62% moisture, 10.22% fiber, 9.34% ash, 9.26% protein and 1.04% lipid was used to compare the extraction time of protein using ultrasonic alkaline assisted extraction and the conventional alkaline method. Ultrasonic assisted extraction powers of 40, 60, 80 and 100W and treatment times ranging from 5-40 min were investigated. It was found that the extraction time decreased with increasing ultrasonic power. Optimum protein extraction, or the greatest extraction rate, was obtained at 100W for 5 min, whereas the conventional method took 60 min. The rate of protein extraction was reasonably described by a first order kinetic model. The reaction rate constants were 0.0065, 0.0106, 0.0270 and 0.1028 min-1 at 40, 60, 80 and 100W respectively. In all cases, the coefficient of determination value (R2) ranged between 0.9123 and 0.9612. The scanning electron microscope (SEM) images of the residual rice bran revealed that after using the ultrasonic method, the cell walls were damaged more than with the alkaline conventional method. The properties of defatted rice bran protein concentrate (DRBPC) obtained using the ultrasonic (100 W for 5 min) and conventional methods showed no significant difference in bulk densities (P>0.05), but the yield using ultrasonication was higher at 4.45 and 2.70% respectively. Furthermore, the size of the protein particles were bigger (by observation) and lighter brown (P<0.05) using the ultrasonication method. In terms of the functional properties of both samples, foam and emulsifying stability were not significantly different (P>0.05). On the other hand, the water and oil absorptionusing ultrasonication were higher than those using the conventional method (P<0.05), and the foam capacity and emulsion activity using the conventional method were higher than those using ultrasonicaiton (P≤0.05). The nitrogen solubility index of both DRBPC samples had similar profiles with the lowest solubility at pH 4-6.The amino acid concentrations of methionine, cysteine and serine were higher using the conventional method (P< 0.05). The percentage of essential amino acids in the DRBPC sample using the ultrasonication method was higher than that using the conventional method (P<0.05) at 52.46 and 47.36% respectively. The predicted protein efficiency ratio (P-PER), Leu/Ile, and the difference between Leu and Ile were not significantly different (P>0.05). The amino acid composition of the DRBPC samples was similar in acidic, basic and hydrophobic amino acid concentrations. However, the concentration of uncharged polar amino acids of the DRBPC samples using the conventional method was higher than that using the ultrasonication method at 25.19 and 17.53 mg/100 g of protein respectively. At present, protein and vitamin delivery are promising areas of encapsulation research since they can be used as nutrition supplements. Therefore, the encapsulation of DRBPC was also investigated in this study. Three different components, alginate, protein and tocopherol acetate, were optimized using response surface analysis. Sodium alginate was used as a coating material, while DRBPC behaved as a coating material and emulsifier, and tocopherol acetate performed as a core material. Tocopherol acetate was used as model fat soluble nutrients in microcapsules. The protein encapsulation yield ranged from 78.22 to 99.27%, while the tocopherol acetate yield ranged from 2.45 to 75.80%. The prediction equation was solved for tocopherol acetate and predicted a ranged from 13.43 and 71.98%. The optimum values of alginate, protein and tocopherol acetate were 1.63, 1.36, 0.88% respectively, while the predicted protein and tocopherol yields were 96.98 and 69.81% respectively. In addition, a higher amount of DRBPC resulted in a darker color of encapsulation, and the SEM image of the encapsulation powder showed that the higher ivamount of DRBPC resulted in a spherical shape with less surface denting. A higher amount of alginate, but lower amounts of protein and tocopherol acetate, resulted in a more porous encapsulation surface than with higher amounts of protein and tocopherol. The cumulative release of tocopherol acetate in both simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) increased rapidly during the first 6 hr and then leveled of after 12 hr with only a gradual release. After 24 hr, the cumulative release of tocopherol acetate was 57 mg (98%) in SGF and 44 mg (76%) in SIF. The final application of DRBPC that was studied the using of protein fortification on dried broken rice. In this study, white aromatic, brown aromatic (both of the KDML105 variety) and black rice were compared with coated broken rice prepared by coating white broken rice (KDML105) with DRBPC. For the proximate composition, the coated broken rice had the highest protein content at about two times greater than the others. Light microscopy showed that the coated broken rice had a thicker layer than the others. The comparison of rice varieties before cooking was significantly different in all color parameters. However, a comparison of rice color before and after cooking showed that black rice was significantly different while the other rice varieties were not. All types of broken rice were cooked as porridge and evaluated using a preference test on a 9 point hedonic scale. The sensory assessment found that white porridge had the highest score for appearance than others. The white and brown porridge were similar in color but coated broken rice porridge was significantly different. In addition, the odor and texture of the porridge samples were alike. For the overall preference, the white porridge had the highest score at 6.82 but brown and black broken rice were the same. |
| Year | 2010 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. FB-10-01 |
| 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 | Food Engineering and Bioprocess Technology (FB) |
| Chairperson(s) | Athapol Noomhorm |
| Examination Committee(s) | Rakshit, Sudip Kumar;Yakupitiyage, Amararatne;Anal, Anil Kumar; |
| Scholarship Donor(s) | Payap University, Thailand;RTG Fellowship |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 2010 |