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1.
Shim JH Kim YW Kim TJ Chae HY Park JH Cha H Kim JW Kim YR Schaefer T Spendler T Moon TW Park KH 《Protein engineering, design & selection : PEDS》2004,17(3):205-211
In an effort to improve the properties of cyclodextrin glucanotransferase (CGTase) as an antistaling enzyme, error-prone PCR was used to introduce random mutations into a CGTase cloned from alkalophilic Bacillus sp. I-5 (CGTase I-5). A mutant CGTase[3-18] with the three mutations M234T, F259I and V591A was selected by agar plate assay. Sequence alignment of various CGTases indicated that M234 and F259 are located in the vicinity of the catalytic sites of the enzyme and V591 in the starch binding domain E. The cyclization activity of CGTase[3-18] was dramatically decreased by 10-fold, while the hydrolyzing activity was increased by up to 15-fold. These mutations near subsite +1 (M234T) and at subsite +2 (F259I) are likely to alter the enzyme activity in a concerted manner, promoting hydrolysis of substrate while retarding cyclization. The addition of CGTase[3-18] reduced the retrogradation rate of bread by as much as did the commercial antistaling enzyme Novamyl during 7-day storage at 4 degrees C. No cyclodextrin (CD) was detected in bread treated with CGTase[3-18], whereas 21 mg of CD per 10 g of bread was produced in bread treated with wild-type CGTase. 相似文献
2.
Food Science and Biotechnology - Rosemary extract (RE) has significant antioxidant and antibacterial properties; however, the application of RE to areas with an aqueous solution is limited due to... 相似文献
3.
Chu Sun Hong Jung Sun Rho Shin-Joung Park Jiyoung Han Sang-Ik Kim Young-Wan Kim Yong-Ro 《Food science and biotechnology》2016,25(5):1413-1419
Food Science and Biotechnology - An optimal reaction condition for producing cycloamylose (CA) from sweet potato starch was investigated using a combination of isoamylase (from Pseudomonas sp.) and... 相似文献
4.
Sun-Hee?Yoon Min-Su?Kim Yong-Ro?Kim Young-Wan?KimEmail author 《Food science and biotechnology》2015,24(5):1811-1816
4-α-Glucanotransferases (αGTases) are useful enzymes to modify starch structure using their unique hydrolysis pattern and transglycosylation activity. In spite of lacking of a carbohydrate binding module, a thermostable aGTase from Thermus thermophilus (TTαGT) bound to insoluble amylose, leading to simple recovery of the enzyme-amylose complex using centrifugation. At a preparative scale, the recovery yield was 40.3% of the subjected free enzyme via collection of the complex twice. The complex exhibited improved thermostability, which shifted the optimum temperature from 70 to 80°C and increased the half-life at 90°C by three-fold compared with the free enzyme. Texture profile analysis of the gels made of modified starch by either free TTαGT or the complex revealed that the complex with double dosage showed the performance similar to free TTαGT in the modification of starch. In conclusion, the purification method described here would be useful due to easy scale-up and simple process without chromatographic process. 相似文献
5.
Saehun Mun Yongdoo Choi Shin-Joung Rho Choon-Gil Kang Chan-Ho Park Yong-Ro Kim 《Journal of food science》2010,75(2):E116-E125
ABSTRACT: In this study we tried to prepare stable water-in-oil-in-water (W/O/W) emulsions using polyglycerol polyricinoleate (PGPR) as a hydrophobic emulsifier and whey protein isolate (WPI) as a hydrophilic emulsifier. At first, water-in-oil (W/O) emulsions was prepared, and then 40 wt% of this W/O emulsion was homogenized with 60 wt% aqueous solution of different WPI contents (2, 4, and 6 wt% WPI) using a high-pressure homogenizer (14 and 22 MPa) to produce W/O/W emulsions. The mean size of final W/O/W droplets ranged from 3.3 to 9.9 μm in diameter depending on the concentrations of PGPR and WPI. It was shown that most of the W/O/W droplets were small (<5 μm) in size but a small population of large oil droplets (d > 20 μm) was also occasionally observed. W/O/W emulsions prepared at the homogenization pressure of 22 MPa had a larger mean droplet size than that prepared at 14 MPa, and showed a microstructure consisting of mainly approximately 6 to 7-μm droplets. When a water-soluble dye PTSA as a model ingredient was loaded in the inner water phase, all W/O/W emulsions showed a high encapsulation efficiency of the dye (>90%) in the inner water phase. Even after 2 wk of storage, >90% of the encapsulated dye still remained in the inner water phase; however, severe droplet aggregation was observed at relatively high PGPR and WPI concentrations. 相似文献
6.
The present study was performed to investigate the possibility of using 4-α-glucanotransferase (4αGTase)-treated starch in W/O/W emulsions to increase their encapsulation efficiency (EE) and stability. Emulsions were prepared using soybean oil, polyglycerol polyricinoleate (PGPR), 4αGTase-treated starch and Tween 20. The mean diameter of W/O/W droplets ranged from 4 to 10 μm depending on the sonication time. When the dye was loaded in the internal water phase, the emulsion prepared by sonication for 1 and 2 min showed a high EE of the dye (>90%). The W/O/W emulsion prepared by sonication for 3 min showed an EE of <90%, but this EE was improved by adding 4αGTase-treated starch to the internal water phase. 4αGTase-treated starch was added to the internal water phase of W/O/W emulsions prepared with a low concentration of PGPR, and the PGPR concentration required to maintain an EE >90% was reduced. W/O/W emulsions containing 4αGTase-treated starch also showed better stability against heating and shearing stresses. These results indicated that 4αGTase-treated starch could be used in the preparation of W/O/W emulsions, which would allow the formulation of W/O/W emulsions with a reduced surfactant concentration. 相似文献
7.
Jin-Woong Choi So-Hee Kim Saehun Mun Sung-Joon Lee Jae-Yong Shim Yong-Ro Kim 《Food science and biotechnology》2011,20(3):687-694
Reduced-fat sausages were prepared by replacing pork back fat with barley flours of different particle sizes. Three barley
flour fractions with different particle size were obtained by passing the ground barley material through a sieve. Fraction
1 and 2 had a higher water absorption index than other fraction and showed higher peak and final viscosities due to higher
β-glucan content. Therefore, fraction 1 and 2 were used as a fat replacer in preparation of reduced-fat sausages. Response
surface methodology was employed to optimize the formulation of reduced-fat sausage and the effects of fat content and barley
flour paste concentration on the textural properties were analyzed simultaneously. Using a regression model, the optimum formulation
of reduced-fat sausage was calculated. For fraction 1, calculated levels of fat content and paste concentration were 7.6 and
3.9%, and for fraction 2, levels were 6.7 and 6.9%, respectively. 相似文献
8.
Food Science and Biotechnology - Recently, health-conscious consumers have a tendency to avoid the use of modified starch in their food products because of reluctance regarding food additives or... 相似文献
9.
Yoon Sun-Hee Oh You-Kyung Kim Yong-Ro Park Jiyoung Han Sang-Ick Kim Young-Wan 《Food science and biotechnology》2017,26(6):1659-1666
Food Science and Biotechnology - A 4-α-glucanotransferases from Thermus thermophilus (TTαGT) possesses an extra substrate binding site, leading to facile purification of the intact enzyme... 相似文献
10.
Yang Kim Young-Lim Kim Khanh Son Trinh Yong-Ro Kim Tae Wha Moon 《Food science and biotechnology》2012,21(6):1707-1714
Rice flours were treated using a thermostable 4-α-glucanotransferase (GTase) from Thermus aquaticus for 1, 3, and 48 h. Molecular weight of modified rice starch rapidly decreased within 1 h of reaction, then slowed down. As the reaction proceeded, the proportions of short (<DP 11) and long (>DP 30) branched chains of modified starch increased, whereas the proportion of medium chains decreased. Rice cakes were prepared with native and GTase-treated rice flours (substitution at 5%) and kept for 3 and 21 h. Texture profile analysis indicated significantly increased hardness, adhesiveness, chewiness, and resilience in rice cakes containing treated rice flours. Sensory analysis revealed that the rice cakes containing 48 h-treated flour had significantly increased springiness, hardness, toughness, and adhesiveness during both storage periods. Meanwhile, it displayed the lowest starch-like attribute and crumbliness. These results suggested that the substitution for 48 h GTase-treated rice flour could retard the retrogradation of rice cakes. 相似文献