Summary Roasted sweet potato is a popular food because of the attractive aroma produced by the Maillard reaction. However, the roasting process may lead to charred skin. Cooking with superheated (saturated) steam provides a solution to this problem. As the results show, when comparing sweet potatoes cooked by superheated steam, and those roasted for 40 min, respectively, the degree of gelatinisation could reach as high as 95% with only 140 °C superheated steam, while roasting required temperatures up to 240 °C. Moreover, in appearance, the skins of the sweet potatoes cooked using superheated steam were not charred like the roasted ones. However, sweet potatoes roasted at 240 °C for 60 min had the highest overall sensory score. When comparing the antioxidant activity, the sweet potatoes cooked by superheated steam had the highest content of total phenol and flavonoids, the best scavenging ability of 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) and the highest ferric‐reducing ability of plasma (FRAP).

WanKao (rice curd) products, included control and added pregelatinized waxy rice flour (PWRF) retarding agent, were prepared and evaluated by texture profile analysis and sensory evaluation. The results showed that the amylose complexing index of the WanKao products contained PWRF were higher than the control, and directly added α‐amylase or monoglycerides. Upon storage, WanKao products contained PWRF showed higher water activity and starch digestibility than those added α‐amylase or monoglycerides. The hardness and soluble starch content of WanKao products contained PWRF were significant lower than those of added α‐amylase or monoglycerides and the control. The WanKao products added PWRF also exhibited softer texture during storage. For sensory evaluation, the higher score of was the added PWRF‐D (contains 100 g of waxy rice flour, 200 g of water, 6% of monoglycerides and 400 mg/kg of α‐amylase) WanKao product presented higher overall acceptability than that of added α‐amylase, monoglycerides, and control either fresh or after low‐temperature storage (5C for 5 days). As a result, the texture qualities of WanKao could be improved by the addition of the PWRF and also the staling and retrogradation rates were further retarded. PRACTICAL APPLICATIONS Taiwan's consumers demand for high quality WanKao products, i.e., softer, slow to staling and retrogradation, and good acceptability. Our results indicated that the qualities of WanKao could be improved by the addition of the novel retarding agent, PWRF, and the staling and retrogradation rates were further retarded.

Pteris multifida Poiret (Pteridaceae), also known as Fong‐Wei‐Cao, is the most commonly used material in herb beverages in Taiwan and also used as one of the vegetable resources in Main China. The aqueous extract of P. multifida Poiret (AEPM) was prepared and its antioxidant and free radical‐scavenging activities were studied. AEPM showed high antioxidant activities by conjugated diene method. At 20 mg/mL, AEPM exhibited high scavenging effects on α‐diphenyl‐β‐picrylhydrazyl, hydroxyl, ferrous radical (82.5, 80.1 and 85.4, respectively) and reducing power (Abs, 700 nm = 1.03). AEPM has various antioxidant activities that may be due to the different naturally occurring antioxidant components. PRACTICAL APPLICATIONS Consumers need high‐quality herb‐beverage products and to understand their potential functions. Our results indicated that the qualities of aqueous extract of P. multifida Poiret possess antioxidant and free radical‐scavenging activities and this evidence could be regard as the important scientific basis.