Optimising the tenderisation and saturated fat reduction in beef by ginger extract using response surface method / Assoc. Prof. Dr. Zainal Samicho, Assoc. Prof. Dr. Norashikin Saim and Dr. Azami Zaharim

The purpose of this study was to investigate the usage of ginger ("Halia Putih": Zingiber officinale Rose, var Officinale and "Halia Bara": Zingiber officinale Rose, var Rhubrum Thailade) on the tenderisation and saturated fat reduction of beef. Ginger extracts were diluted in the range of 20% - 100%. Physical properties for both ginger extracts such as cloudiness, acidity, pulp content and total soluble solid were determined using UV-Vis spectrophotometer, pH meter, centrifuge machine and hand refractometer respectively. It was found that the more ginger extract diluted, the higher pH values vice verse for the percentage of pulp content, total soluble solid and absorbance values. By using Response Surface Method of the MrNITAB software (version 14), experimental design could be created whereby variables such as ginger extract concentration, temperature and time of immersion were involved. Beef were immersed in different ginger extract concentrations and shaken in shaking water bath with temperatures ranging from 30°C to 70°C, for immersion times ranging from 5 to 25 minutes. The tenderisation of treated beef was immediately measured using Texture Analyzer, TX TA2i with P2N needle probe. The optimum conditions for beef tenderisation using "Halia Putih" and "Halia Bara" could be determined using regression equations and response surface models of response surface methodology. The highest increment of tenderisation in beef was determined in beef which was treated with "Halia Bara" that is 60.88% at the optimum condition: 100% ginger extract concentration, immersion temperature of 30°C and immersion time of 18 minutes. "Halia Bara" showed tremendous activity in reducing toughness in beef compared to "Halia Putih". It was found that only test variable, concentration of ginger extract (Xj) gave significant effect at 5% level on the percentage increment of beef tenderisation. To determine the saturated fat content of beef such as myristic, palmitic and stearic acids, about 1 u.1 methyl ester was injected to Gas Chromathography (Hewlett Packard, 5890 Series II). The highest reduction of myristic acid content that could be predicted was up to 71.12% when beef was treated with "Halia Bara" at the feasible optimum condition of 100% ginger extract concentration, immersion temperature of 70°C and immersion time of 14.3 minutes. The highest reduction of palmitic acid content that could be predicted was up to 79.93% when beef was treated with "Halia Bara" at the feasible optimum condition of 99% ginger extract concentration, immersion temperature of 30°C and immersion time of 5 minutes. The highest reduction of stearic acid content that could be predicted was up to 76.83% when beef was treated with "Halia Bara" at the feasible optimum condition of 100% ginger extract concentration, immersion temperature of 70°C and immersion time of 16.7 minutes. In addition, the significant regression equations or models at 5% levels were also created for the estimation of the percentage reduction of tenderisation and saturated fat in beef which was treated with "Halia Putih" and "Halia Bara".