Tuyen C. Kha

Microencapsulation of gac oil by spray drying: optimization of wall material concentration and oil load using response surface methodology

The objective of this study was to optimize the wall material concentration and the oil load on the encapsulation of Gac oil using spray drying by response surface methodology. Results showed that the quadratic polynomial model was sufficient to describe and predict encapsulation efficiencies in terms of oil, β-carotene, lycopene, peroxide value (PV), moisture content (MC), and total color difference (Δ E) with R 2 values of 0.96, 0.95, 0.86, 0.89, 0.88, and 0.87, respectively. Under optimum conditions (wall concentration of 29.5 % and oil load of 0.2), the encapsulation efficiencies for oil, β-carotene, lycopene, PV, MC, and Δ E were predicted and confirmed as 92 %, 80 %, 74 %, 3.91 meq/kg, 4.14 % and 12.38, respectively. The physical properties of the encapsulated oil powders obtained by different formulations were also determined. It was concluded that the protein-polysaccharide matrix as the wall material was effectively used for spray-drying encapsulation of Gac oil.

Bitter Melon ( Momordica charantia L.) bioactive composition and health benefits: A review

ABSTRACT Bitter melon (Momordica charantia L.) has traditionally been used as a medicinal food in many developing countries. It is a tropical fruit claimed to have therapeutic effects due to its content of bioactive compounds. The present review is an attempt to highlight the bitter melon varieties, bioactive composition that is linked to its therapeutic effects, especially antidiabetic effect, in vitro and in vivo models, and understanding of the mechanisms of actions of bitter melon that are associated with epidemiological evidences. This paper also outlines a proposed processing scheme aiming to fully utilize bitter melon and add further value to this fruit.

Gac Fruit: Nutrient and Phytochemical Composition, and Options for Processing

Momordica cochinchinensis Spreng or Gac fruits are rich in nutrients, including carotenoids, fatty acids, vitamin E, polyphenol compounds, and flavonoids. Medicinal compounds are also found in the seeds, but the benefits of traditional preparations from these need to be clarified. The plant has the potential to be a high-value crop, particularly as parts of the fruit can be processed into nutrient supplements and/or natural orange and yellow colorants. However, the plant remains underutilized. There is limited information on its requirements in production, and the processing of health products from the fruits is a relatively new area of endeavor. The versatility of the fruit is highlighted through processing options outlined for fruit aril, seeds, pulp, and skin into powders and/or encapsulated oil products. These Gac fruit products will have the potential to be utilized in a range of foods such as pasteurized juice and milk beverages, glutinous rice, yogurt, pasta, and sauces.

Effects of pre-treatments and air drying temperatures on colour and antioxidant properties of Gac fruit powder

Gac fruit contains extraordinarily high levels of carotenoids that are well-known as strong antioxidants with an attractive yellow-orange-red colour. The aim of this study was to investigate the effects of different pre-treatments and air drying temperatures on colour characteristics, total carotenoid content (TCC) and total antioxidant activity (TAA) of resultant Gac fruit powder. Results showed that pre-soaking in solutions of ascorbic acid or bisulfite prior to air drying at low temperature of 40°C was effective in preserving TCC and TAA. Loss of TCC and TAA increased as drying temperatures increased (50, 60, 70, and 80°C). Moreover, the colour characteristics of Gac powder, such as chroma and hue angle, were not significantly affected by pre-treatments and air drying temperatures. The sorption isotherm curve of Gac aril powder has sigmoid shape.

Ultrasound-Assisted Aqueous Extraction of Oil and Carotenoids from Microwave-Dried Gac (Momordica cochinchinensis Spreng) Aril

Abstract The study aimed to optimise the ultrasound-assisted aqueous extraction of oil, β-carotene and lycopene from powdered microwave-dried gac arils. Ultrasound power, extraction time, powder particle size and the ratio of water to gac powder during the extraction, the centrifugal force used to recover the extracted components were investigated. Microwave-drying followed by aqueous extraction without ultrasound-assistance and air-drying followed by aqueous extraction with or without ultrasound-assistance was also carried out for comparisons. The gac material left behind after the extractions was also investigated using scanning electron microscopy (SEM). The results showed that ultrasound power of 32 W/g of aril powder, extraction time of 20 min, powder particle sizes of 0.3–0.5 mm, a ratio of water to powder of 9 g/g and a centrifugal force of 6,750×g gave optimal extraction efficiencies for oil (90%), β-carotene (84%) and lycopene (83%), and the oil had a low peroxide value (PV) of 2.2 meq/kg. The SEM analysis confirmed that the combination of microwave-drying followed by ultrasound-assisted aqueous extraction caused strong disruption of the gac aril cellular structures, which was consistent with the high extraction of oil, β-carotene and lycopene obtained with the combination. It was concluded that gac oil containing high amounts of β-carotene and lycopene and having a low PV could be extracted using microwave-drying and ultrasound-assisted aqueous extraction.

Effect of Drying Pre-treatments on the Yield and Bioactive Content of Oil Extracted from Gac Aril

Abstract Gac fruit (Momordica cochinchinensis Spreng) aril contains high levels of bioactive compounds including β-carotene, lycopene and fatty acids. Therefore, it is important to find an extraction method of Gac oil resulting in the highest content of bioactive compounds. The effects of microwave and air-drying pre-treatments of Gac aril prior to hydraulic pressing and Soxhlet extraction on the oil yield, nutrients and chemical properties of the oil were compared. Results showed that the highest oil yield could be obtained when the aril was microwave-dried before Soxhlet extraction. This finding was explained by microstructural changes of the dried arils. Microwave-drying prior to pressing resulted in the highest content of β-carotene (174 mg/100 mL) and lycopene (511 mg/100 mL) in the oil extract. Oleic acid (48%) and linoleic acid (18%) were found to be the dominant fatty acids in the oil extracts. Gac oil with the lowest acid (0.69 mg KOH/g) and peroxide values (1.80 meq O2/kg) was extracted when microwave-drying was applied prior to pressing. It can be concluded that the microwave drying pre-treatment before pressing was better than the air-drying pre-treatment for extracting Gac oil of high quality.

Optimising the Encapsulation of an Aqueous Bitter Melon Extract by Spray-Drying

Our aim was to optimise the encapsulation of an aqueous bitter melon extract by spray-drying with maltodextrin (MD) and gum Arabic (GA). The response surface methodology models accurately predicted the process yield and retentions of bioactive concentrations and activity (R2 > 0.87). The optimal formulation was predicted and validated as 35% (w/w) stock solution (MD:GA, 1:1) and a ratio of 1.5:1 g/g of the extract to the stock solution. The spray-dried powder had a high process yield (66.2% ± 9.4%) and high retention (>79.5% ± 8.4%) and the quality of the powder was high. Therefore, the bitter melon extract was well encapsulated into a powder using MD/GA and spray-drying.