Screening of Fungal Strains Grown in Solid-state Culture for Production of Pectinase from Coffee Husk

Eighty percent of Vietnamese coffee production can be found in Central Highlands (Tay Nguyen). This paper describes a screening of fungi strains isolated from coffee husk waste collected in Dak Lak province, Tay Nguyen, for pectinase production. It was found that 17 different fungi strains were isolated from samples of 11 coffee farms. Among them. there were only 9 trains which could hydrolyze pectin. The diameter of the hydrolysis halo around fungi colonies in Pectinase Screening Agar Medium (PSAM) was measured as an indicator to assess the pectinase activity. Phylogenetic analysis based on 28S rRNA gene sequences showed that detected Rhizopus oryzae. Aspergillus oryzae and Hypocrea pseudokoningii were those giving the largest holo zones. Hypocrea pseudokoningii presented the best pectinase activity of 657.16 UI/g and was chosen for biomass production to collect enzyme. In a further study, effect of rice bran addition to coffee husk and moisture of culture medium on the spore yield of Hypocrea pseudokoningii were investigated. Using coffee husk medium with 23% rice bran addition and 65% moisture at ambient temperature, the highest spore yield of 9.2 x108 spores/g was found after incubation for 168 hours. The fungi biomass product was dried at 40oC for 54 hours to obtain the final moisture of 12% and spore survival of 5.9 x108 spores/g. 

Effects of Cooking Methods on the Changes of Total Anthocyanins, Phenolics Content and Physical Characteristics of Purple-Fleshed Sweet Potato (Ipomoea batatas L.) Grown in Vietnam

Total anthocyanin content (TAC) and total phenolics in “Nhật tím” purple-fleshed sweet potato (PFSP) variety were analyzed as affected by four cooking methods: steaming, baking, roasting, and frying. Moisture content (%), core flesh temperature (oC) and color characteristics of cooked PFSP were evaluated. TAC in steamed, fried (skin-on), roasted, baked, and fried (skin-off) PFSP were 234.18; 217.14; 208.11; 195.25; 173.68 mg/100g dry weight (DW), respectively. Under the same cooking time, steaming was good for the retention of total phenolics and anthocyanins as compared with baking. Cooking by steaming, roasting, baking, skin-on or skin-off frying produced significant increase (P ≤ 0.05) of TAC and total phenolics as compared to the respective fresh samples. Steaming resulted in the greatest increase of TAC whereas skin-on frying showed a good cooking method to retain high total phenolics (826.47 mg GAE/100g DW) in shred PFSP

Effect of Non-thermal Plasma on Physicochemical Properties of Nam Dok Mai Mango

Mango is considered as a popular and economically important tropical fruit around the world because of its attractive color, favorable flavor, and high nutritional quality. Nowadays, more consumers consciously desire not only fresh and nutritious but also safe fruits with low or free of microorganisms and chemical contamination. Non-thermal plasma (NTP) is one of the emerging technologies that could potentially decontaminate the fresh food and food processing surfaces. Recently, NTP emerges as a new sanitizing method in the agro-industrial application, where the qualitative characteristics of the treated product could probably be modified by the reactive species as well as the residues of oxidation processes. This study evaluates the changes of physicochemical indexes of Nam Dok Mai mango treated with several NTP conditions. The NTP process was discharged in 0.05 % sodium bicarbonate solution under different voltage levels (800-1500 V) and various treatment durations (2-10 min). It was found that there were significant decreases (p<0.05) in titratable acidity and total phenolic content of NTP treated mango, while the total soluble solid showed a significant increase (p<0.05). The color and texture parameters of this fruit with NTP treatments were not significantly different (p>0.05). The results demonstrated that NTP had slight effect on the physicochemical properties of mango. Future work is required to investigate more comprehensive effect of NTP on the pesticides residues in the mango

Extraction of oil and minor compounds from oil palm fruit with supercritical carbon dioxide

A significant quantity of tocochromanols and carotenoids remains in the residual from palm oil production by traditional screw pressing. Supercritical carbon dioxide extraction was used as alternative method with the purpose to recover better these valuable minor compounds. Total oil yield and co-extracted water were investigated in the course of extraction. Tocochromanols and carotenoids were evaluated, not only in the extraction oil, but also in the oil of residual fibre. Modelling of extraction process was also performed for a further up-scaling. The results showed that oil yield up to 90% could be observed within 120 min. Supercritical carbon dioxide (SCCO2) could extract tocochromanols and carotenoids with concentration in the same range of normal commercial processing palm oil, while co-extracted water remained rather low at a level of 2–4%. Moreover, recovery efficiencies of these minor compounds were much higher in case of extraction processed with supercritical carbon dioxide than those with screw pressing method

Effect of Non-thermal Plasma on Physicochemical Properties of Nam Dok Mai Mango

Mango is considered as a popular and economically important tropical fruit around the world because of its attractive color, favorable flavor, and high nutritional quality. Nowadays, more consumers consciously desire not only fresh and nutritious but also safe fruits with low or free of microorganisms and chemical contamination. Non-thermal plasma (NTP) is one of the emerging technologies that could potentially decontaminate the fresh food and food processing surfaces. Recently, NTP emerges as a new sanitizing method in the agro-industrial application, where the qualitative characteristics of the treated product could probably be modified by the reactive species as well as the residues of oxidation processes. This study evaluates the changes of physicochemical indexes of Nam Dok Mai mango treated with several NTP conditions. The NTP process was discharged in 0.05 % sodium bicarbonate solution under different voltage levels (800-1500 V) and various treatment durations (2-10 min). It was found that there were significant decreases (

Effects of pre-treatments on the yield and carotenoid content of Gac oil using supercritical carbon dioxide extraction

The effects of air-drying temperature, particle size and enzymatic pre-treatment on the oil yield and content of carotenoids in the resultant Gac oil using supercritical CO₂ extraction method were investigated. It was found that the highest oil yield was obtained when using the enzyme concentration at 0.1% (w/w) for pretreatment before air-drying. Furthermore, the content of carotenoids was also enhanced by suitable drying temperature and the particle size. High oil yield (34% g/g) and high content of β-carotene (83 mg/100 mL oil) and lycopene (508 mg/100 mL oil) were obtained using the drying temperature of 50°C and particle size of 0.45 mm as pre-treatments prior to SC-CO₂ extraction at pressure of 200 bar and extraction temperature of 50°C. Results also indicated that the most suitable extraction time was 120 min. It was concluded that Gac oil containing high amount of carotenoids could be extracted using the chosen air-drying temperature, particle size, enzymatic pre-treatment and extraction time

Non-thermal plasma for elimination of pesticide residues in mango

The effects of non-thermal plasma (NTP) on elimination of pesticide residues and on quality changes of mango (cv. Nam Dok Mai) were investigated. Varied flow rate of Ar gas (2, 5 and 8 L/min) and time dependent degradations of chlorpyrifos and cypermethrin as a result of NTP treatments using a gliding arc (GA) discharge for 5 or 10 min were studied. Results showed that the NTP treatment for 5 min at 5 L/min Ar flow rate successfully decreased the concentrations of chorpyrifos by 74.0% and cypermetrin by 62.9%. There were significant (p ≤ 0.05) decreases in titratable acidity and total phenolic content and increases in carotenoid content for the treated mangoes. However, total soluble solid, color and texture parameters were not significantly different (p > 0.05). The emission signal of hydroxyl (OH) radicals at 309 nm was also obtained to monitor that the system was working properly