Abstract:
With the increase in global demand for healthy foods, public preference for natural sweeteners has increased. A natural sweetener with high sweetness and bioactivity would be beneficial to human health. In this direction, the current research aimed to develop a novel food ingredient from monk fruit (Siraitia grosvenorii (Swingle) C. Jeffrey ex Lu et Z. Y. Zhang) extract to be used as a natural sweetener to substitute sugar. A previous study has reported the presence of mogroside V, an antioxidant that gives zero-calorie and high sweetness in the monk fruit extract. In the study, determination of mogroside V content was conducted to evaluate the extraction efficiency from monk fruit. Microencapsulation of the extract via spray drying was conducted to obtain monk fruit powder with good quality and storage stability as well as a high retention rate of mogroside V. The relative sweetness, sensory profile, and consumer acceptance of the spray-dried monk fruit powder were evaluated.
According to the results, the optimal extraction conditions for the monk fruit extract were obtained at the sample-water ratio of 1:40, extract temperature of 80℃ and extraction time of 20min. Under these conditions, the extraction efficiency of mogroside V was the highest, which was 19.03 mg mogroside V/g sample. The extract containing the highest mogroside V was spray-dried by screening different wall materials and their combinations as well as finding suitable spray drying conditions. The following conditions were finally determined to prepare the spray-dried powder: wall material consisted of Gum Arabic (GA) and Whey Protein Isolate (WPI) at 1:1 ratio; the core-wall ratio of 1:2; inlet temperature at 180℃ with the feed rate of 20%. The spray-dried powder obtained under such conditions has the lowest water activity (0.2196), moisture content (5.26%), hygroscopicity (11.54g water/100g dry powder), water solubility index (91.35%) and the highest mogroside V retention (85.38%).
Sensory evaluation of the encapsulated monk fruit extract revealed the relative sweetness of the powder as 3.88 folds compared to that of sucrose. The powder had the aroma of succade, cocoa, caramel, herbal, and a weak fruity and sourdough-like odours. Moreover, it also gives a sweet and liquorice taste, with weak herbal, caramel-like, sour and bitter and succade-like flavour. The results from the consumer acceptance test showed that the overall acceptance of monk fruit powder
sweetened products (cookies and black tea) was above satisfactory, indicating good application potential of the monk fruit extracts in food products as a natural sweetener.
In summary, the monk fruit powder obtained by water extraction followed by spray drying encapsulation has a higher sweetness level than sugar (sucrose). It imparts a unique flavour with reasonably good consumer acceptability. Therefore, the monk fruit powder could be a promising natural sweetener to be applied in food formulations for people with diabetes or those who like the sweet flavour but do not want the extra calories or sugar content.