วิทยานิพนธ์ (Thesis)

Study on UV-C irradiation in fruits : Ripening quality and bioactive compounds in mango and defense mechanism in tangerine

2026-01-06T09:15:37Z

Study on UV-C irradiation in fruits : Ripening quality and bioactive compounds in mango and defense mechanism in tangerine Amelia Safitri Sutthiwal Setha Thesis (M.Sc.) -- Food Technology, School of Agro-Industry. Mae Fah Luang University, 2015

ฤทธิ์การด้านออกซิเดชันและฤทธิ์การต้านจุลินทรีย์ของพุทราไต้หวันพันธุ์ซื่อมี่ ในจังหวัดเชียงราย

2025-09-30T04:30:17Z

ฤทธิ์การด้านออกซิเดชันและฤทธิ์การต้านจุลินทรีย์ของพุทราไต้หวันพันธุ์ซื่อมี่ ในจังหวัดเชียงราย วารินทร์ สารเขื่อนแก้ว นิรมล ปัญญ์บุศยกุล วิทยานิพนธ์ (วท.ม.) -- สาขาวิชาเทคโนโลยีการอาหาร, สำนักวิชาอุตสาหกรรมเกษตร. มหาวิทยาลัยแม่ฟ้าหลวง, 2556

Development of active film from giant catfish skin gelatin incorporated with antioxidant extract from some tropical fruit seeds

2025-06-13T01:40:07Z

Development of active film from giant catfish skin gelatin incorporated with antioxidant extract from some tropical fruit seeds Samart Sui-ut Saroat Rawdkuen This study was aimed to investigate the extraction of gelatin and development the active gelatin film from giant catfish skin incorporated with fruit seeds antioxidant extracts. Gelatin was extracted from giant catfish (Pangasianodon gigas) skin using distilled water at 45°C for 12 h. The re-extraction process was also investigated to obtain a high gelatin recovery. The first extraction was done by incubating the pretreated acid-treated fish skin at 45 °C for 12 h. The remnant was re-extracted at temperatures of 60–90 °C for 1–12 h. The gelatin yield of the first extraction was 10.14%, while the re-extraction at 90 °C provided higher recovery (19.5%). Low band intensity of α1 and α2 chains of gelatin was observed after re-extraction at high temperature for a longer time. The absorption bands of amide I (1,653 cm-1) and II (1,542 cm-1) from both extracted gelatins were similar. The obtained results suggested that the gelatin re-extraction process could be applied for other skin sources to obtain high gelatin recovery with the desired properties. Solid–liquid extraction and response surface methodology (RSM) were used to optimise conditions for the extraction of phenolic compounds from longan (Dimocarpus longan Lour.), lychee (Litchi chinensis Sonn.), passion fruit (Passiflora edulis), and rambutan (Nephelium lappaceum) seeds. The independent processing variables were ethanol concentration, temperature and time. Ethanol concentration and temperature significantly affected extraction yield, extractable phenolic content (EPC), and antioxidant activities including DPPH-, ABTS-radical scarvenging activity, and ferric reducing/antioxidant power (FRAP). According to the prediction value at optimum condition, longan seed had highest extraction yield, EPC, and antioxidant activities compared with lychee, passion fruit, and rambutan seed extracts. The optimal conditions for longan seed extraction based on combination responses were 53 % (v/v) ethanol, 58 °C, and 139 min. These optimum conditions yielded EPC of 5,804 mg gallic acid equivalents (GAE)/100 g dry sample with DPPH-, ABTS- radical scanvenging activity, and FRAP values of 2,442, 8,620, and 3,609 GAE/100 g dry samples, respectively. The experimental values were well agreed with those predicted values. Thus longan seed was used to extract antioxidant compound for development of active gelatin film. Gelatin films incorporated with longan seeds (LS) extract or butylated hydroxytoluene (BHT) at different concentrations were developed and characterized. The properties including tensile strength (TS), elongation at break (EAB), protein solubility and FTIR spectra of the films were similar to the film made without LS or BHT. The ncrease in redness (a*) and yellowness (b*) values of film were observed with the increasing concentration of LS extract (P < .05). The results showed some interactions of phenolic compounds in LS extracts, especially when LS was added at higher concentration as evidenced by the higher glass transition temperature, decreased in EAB, and increased water solubility of the films. Films with LS extract or BHT incorporated showed preventive effect on lipid oxidation of soybean oil. The peroxide formation (PV), conjugated diene (CD), and thiobarbituric acid reactive substances (TBARS) values of soybean oil slowly changed compared with the control film. Thesis (M.Sc) -- Food Technology, School of Agro-Industry. Mae Fah Luang University, 2008

Separation, characterization and application of bromelain from pineapple wastes in Chiang Rai

2025-05-14T08:03:21Z

Separation, characterization and application of bromelain from pineapple wastes in Chiang Rai Sunantha Ketnawa Saroat Rawdkuen This study investigated the extraction, isolation, characterization and application of bromelain extract from wastes of Nang Lae and Phu Lae pineapple cultivars. The waste portions such as the peel, core, stem and crown were 29-40, 9-10, 2-5 and 2-4% (w/w), respectively. The extract of crown from both cultivars gave the highest proteolytic activity and protein contents. The peel was considered as the source with the highest potential for bromelain extraction. The best extractant for bromelain extraction was sodium phosphate buffer pH 7.0 containing cysteine and EDTA (PB-CE) due to the highest bromelain activity obtained (867 and 1,032 units for Nang Lae and Phu Lae cultvivar, respectively). TCA-soluble peptides content of all the treated muscles (beef, chicken and squid) with bromelain extract increased when the amount of bromelain extract was increased (P<0.05). Reduction in myosin heavy chains (MHC) and actin (AC) was observed in the entire muscle types when bromelain extract was applied. Bromelain from pineapple peel (Nang Lae and Phu Lae cultivars) was predominantly partitioned to the polyethylene glycol (PEG) rich phase in aqueous two-phase system (ATPS). For Nang Lae cultivar, the highest enzyme activity recovery (113.54%) with purification fold of 2.23 was observed in the top phase of 15% PEG2000-14% MgSO4. The bromelain extract showed the highest activity at pH 7.0 and 55°C. Its activity decreased continuously when concentration of NaCl was increased (up to 1.5%, w/v) (P<0.05). The B, a1, a2 of giant catfish skin collagen extensively degraded into lower MW proteins when treated with 0.02 units of the bromelain extract. For Phu Lae cultivar, the best ATPS condition for bromelain partitioning was 18% PEG6000-17% MgSO4, which increased the purity by 3.44-fold and the activity recovery to 205.78%. The obtained bromelain showed the highest relative activity at pH 8.0. The highest activity of bromelain was found at 60°C and then decreased 70% after 5 min of incubation at 90°C. SDS-PAGE and activity staining showed that bromelain from crude extract of both cultivars had the MW approximately 28 kDa. According to the activity recovery, TCA soluble peptides content and hydrolysis of muscle proteins, Phu Lae was selected for application study. The tenderizing effect of bromelain extract powder (0, 3, 7, and 20%, w/w) obtained from the top phase of ATPS comprising of 18% PEG 6000-17% MgSO4 on muscle foods (beef, chicken and squid) was investigated. LOWer of pH and moisture content were observed in the samples treated with bromelain extract, but the TCA-soluble peptides content significantly increased (P<0.05). Reduction of meat firmness, toughness, water holding capacity and cooking yields were observed when the concentration of bromelain extract was increased (P<0.05). Electrophoretic patterns also revealed extensive proteolysis of the treated samples. At the microstructural level, tissue fibers were broken; cell membranes were much more degraded and the generation of numerous gaps was clearly observed when 20% (w/w) of bromelain extract was added. From the results, the bromelain extract derived from two-phase extraction of pineapple peel could be used as an effective meat tenderizer. Results from this study suggests that local pineapple wastes are rich sources of bromelain and application of bromelain as meat tenderizer helps add value to such sources. Thesis (M.Sc) -- Food Technology, School of Agro-Industry. Mae Fah Luang University, 2010