Functional characterization of purified pear protease and its proteolytic activities with casein and myofibrillar proteins

This study was performed to characterize pear protease proteolytic activity and investigate the use of pear protease as a meat tenderizer. Pear protease was purified and stabilized by 5% dextrin during lyophilization (dry) or concentration (liquid). Pear protease was further characterized with respect to pH, thermodynamics, and enzyme kinetics. Pear protease was stable at a pH range of 5-8 with an optimum pH of 6.5. From Arrhenius plots, liquid protease showed higher temperature dependency (23.49 kJ/mol) than dry protease (18.62 kJ/mol) due to its higher activation energy. The kcat/Km, catalytic efficiency of enzyme, was similar with 2.9 and 2.7 µM/min with dry and liquid proteases. Pear protease was evaluated for its proteolytic activities with casein and beef myofibrillar proteins by individually and combination with fig and kiwifruit proteases. These result indicated that pear and kiwifruit proteases could be complementary to be a desirable product for meat tenderization.     

Identification of cellulolytic bacteria associated with tunic softness syndrome in the sea squirt, Halocynthia roretzi

The edible ascidian, sea squirt Halocynthia roretzi (Drasche) is marine invertebrate that is a valuable source of foods and bioactive compounds. A severe disease of the sea squirt characterized by degeneration of tunic fibers formed of bundled cellulose microfibrils has occurred. We hypothesized that bacteria lyse the cellulose fibril structure, cellulase activity may be a causative agent of the disease. Among the bacteria isolated from diseased sea squirt, Pseudoalteromonas sp. NO3 had cellulase activity based on a Congo red overlay assay and starch-reducing activity. Sea squirts exhibited 40–100% cumulative mortality after injection with Pseudoalteromonas sp. NO3 using doses of 2×10⁶?2×10⁸ colony forming unit (CFU)/individual. Dead sea squirts possess thinner and ruptured tunics, which were similar to natural outbreaks. These results suggest that Pseudoalteromonas sp. NO3 possessing cellulase activity is one of the causes of tunic softness syndrome in sea squirt.     

Structure–function relationship of fermented skate skin gelatin-derived bioactive peptides: a peptidomics approach

Food Science and Biotechnology - In this study, we investigated the multi-functionality of bioactive peptides derived from fermented skate (Raja kenojei) skin gelatin hydrolysates. The extracted...     

Encapsulation by spray drying of bioactive components, physicochemical and morphological properties from purple sweet potato

Purple-fleshed sweet potato flour could be used to enhance the colour, flavour and nutrients in food products. Thus, the investigation was to produce encapsulated flours from purple-fleshed sweet potato by spray drying using combinations of various levels of ascorbic acid (5 g kg⁻¹ and 10 g kg⁻¹) and maltodextrin (30 g kg⁻¹ and 100 g kg⁻¹) and to evaluate their effects on bioactive components, physicochemical and morphological properties. Encapsulated flours had higher total phenolic content, antioxidant capacity and water solubility index than non-encapsulated flour. There were no significant differences in anthocyanin content between encapsulated and non-encapsulated flours. However, water absorption index and flavonoids content of encapsulated flours depended on concentrations of ascorbic acid and maltodextrin. In addition, the high concentrations of ascorbic acid and maltodextrin encapsulated flours had higher glass transition temperature as compared to that of lower concentrations. In respect to morphology, the particles of encapsulated flours with high concentration of ascorbic acid and maltodextrin were more aggregated than those encapsulated with lower concentrations. Therefore, flours encapsulated with 10 g kg⁻¹ ascorbic acid and 30 g kg⁻¹ maltodextrin could be used to enhance the antioxidant activities of functional food ingredients.     

Effect of processing conditions on functional properties of collagen powder from skate (<Emphasis Type="Italic">Raja kenojei</Emphasis>) skins

Optimum conditions for collagen extraction from skate (Raja kenojei) skins with various liming concentrations, extraction solution pH, extraction temperature and time, and functional properties were investigated. The optimum conditions for collagen extraction are as combination of place the skins in a lime solution of 0.15 N of NaOH, extract with 5 volumes water (pH 4.0) for 4 hr at 40°C, filter, centrifuge, and lyophilize to obtain collagen powder. The characteristics of skate skin collagen obtained under optimum extraction conditions were: solubility 82.7%, turbidity 0.28, and Hunter color L, a, and b values were 88.4, 0.92, and 11.2, respectively. On the other hand, the acidic pH values (3.0 and 5.0) of collagen were more resistant to precipitation upon extended heating.     

Bioactive compounds and antioxidant activities of Quercus salicina Blume extract

Food Science and Biotechnology - Quercus salicina Blume (QS) is an oak species that is indigenous to Japan and Korea. Historically, extracts of leaves, stems, barks and buds from the QS tree had...     

Optimization of spray drying process parameters for production of Japanese apricot (Prunus mume Sieb. et Zucc.) juice powder

Food Science and Biotechnology - Optimization of spray drying conditions namely inlet air temperature (IAT) and maltodextrin (MD) concentration was utilized by response surface methodology for...     

Effect of temperature on oxidation kinetics of walnut and grape seed oil

The effects of temperature on the oxidation of walnut oil (WO) and grape seed oil (GSO) were investigated. Both oils were stored at 25, 40, 60, and 80°C for 60, 30, 12, and 6 day, respectively. Degree of oxidation was measured in terms of peroxide value (POV), conjugated dienoic acid (CDA) value, and p-anisidine value (p-AV). The rates of increase in POV, CDA, and p-AV in both oils were strongly dependent on storage temperature. The induction period (IP) decreased gradually with increasing storage temperature in both oils. WO showed shorter IPs (23.0, 9.2, and 1.0 day at 25, 40, and 60°C, respectively) than those of GSO (41.5, 12.0, and 1.8 day at 25, 40, and 60°C, respectively), indicating the higher susceptibility of WO to oxidation. The activation energy (Ea) for the IP of WO and GSO autoxidation was similar (75.87 and 75.66 kJ/mol, respectively), revealing similar temperature dependence for autoxidation in WO and GSO.

     

Mechanistic insights on burdock (Arctium lappa L.) extract effects on diabetes mellitus

Food Science and Biotechnology - Diabetes mellitus (DM) type 2 is amongst the most common chronic diseases, being responsible for various problems in humans and contributing to increased mortality...