Sensory evaluation of new lines of oca (Oxalis tuberosa) grown in New Zealand

Five new and one local cultivar of oca or New Zealand yam (Oxalis tuberosa) were evaluated by a consumer-type panel for appearance, flesh colour, flavour, texture and overall acceptability of raw, steamed and baked tubers. The intensity, `just rightʹ or liking scores were analysed using the proportional odds model. Skin and flesh colour of tubers were also measured objectively using a colorimeter. For raw oca, panellists preferred bright red tubers, but size was also important. Flesh colour, bitterness and mealiness were important variables which described the overall acceptability of steamed oca, while only flesh colour and bitterness were important variables for baked oca. Cultivars which had flesh colour described as `bright yellowʹ, flavour as `no bitter tasteʹ, and a `very slightly mealyʹ texture were more preferred. Cultivars with higher yellow/blue (b*) and chroma (c*) values for cooked tuber skin and flesh colours were more acceptable.