In consideration of the market needs, the product is designated a day cream with both sun-screening and anti-oxidant functions. Market survey reveals that customers prefer such a cream product to be non-greasy, soft and with good spreadability. These sensorial and rheological quality factors are translated to corresponding technical specifications, such as emollient content and constituent droplet size. A light cream with low viscosity (6,000-50,000 mPa•s) gives a pleasant spreadability and an oil/water microstructure is preferred due to its non-greasy feel. The cream formula also includes other supporting materials such as emollients, emulsifiers, thickeners, stabilizers, and preservatives, which should be selected to meet the technical specifications and selection criteria. Based on the formula, a prototype cream is fabricated. The prototype is characterized by their pH, droplet size distribution, feel on application, as well as on their stability. If any of the parameters does not meet the specifications, a new prototype is made by adjusting the formula compositions or operating parameters according to a set of heuristics. In addition, a bioassay using rats is established for assessing the biological activity of this anti-oxidant-supplemented sunscreen cream. Significant increases (18-25%) in the amount of natural anti-oxidants, glutathione (GSH) and a-tocopherol (a-TOC), are observed on rat skin treated with FS containing cream by comparing the control cream with no FS. Also, the FS containing cream is found to give protection on the natural anti-oxidant network on the skin against UV irradiation.