3.2.2 Sample Preparation
The mayonnaise samples are prepared from the extraction of salmon fish oil from Salmo salar and grape seed extract from Baccaurea ramiflora.
3.2.2.1 Preparation of Fish Oil
Heat extraction is not suitable to use since access to heating will accelerate lipid oxidation and decreasing oxidative stability of fish oil (Arab-Tehrany et. al., 2012). Hence, the extraction of fish oil from salmon fish is carried out according to the enzymatic extraction as described by Deepika et. al. (2014). First, blend whole salmon fish without addition of water. Next, weigh 1000 g blended fish samples and placed them equally in four 500 mL beakers. Add 100 mL of distilled water to each beaker in the ratio of 1:0.4 (fish: water) and mix the mixture well with the aid of magnetic stirrer. After that, measure the pH value of the mixture using a pH meter and adjust it to pH 6 by adding 1 N hydrochloric
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(2013). Firstly, grind 5.0 g grape seeds into powder to get 40-mesh size powder. Then, defat the grape seed powder with n-hexane (one part powder to ten parts hexane ratio, w/v) and n-hexane is required to remove later in a vacuum oven at 40 °C. Place approximately 0.5 g of the defatted grape seed powder in a centrifuge tube, then mix with 9.5 mL of 70% (v/v) acetone in Milli-Q water and shake for 1 hour in dark at room temperature. Centrifuge the mixture at 8750 g for 15 min at 20 °C and transfer the supernatant into an amber vial. Repeat the procedures for four times collection. Combine all the supernatants and evaporate them to dryness in a vacuum rotary evaporator at 45 °C. FTIR spectroscopy is used to confirm the absence of traces of hexane in the extraction solvent by using a library spectrum as reference for 4000 to 400 cm-1 region. All the procedures are needed to be carried out in dim light because polyphenols are extremely sensitive to