Development of jam from sea lettuce (Ulva lactuca) and yellow passion fruit peel (Passiflora edulis f. flavicarpa)

Abstract

Seaweeds are macroalgae that grow in coastal regions and are a good source of nutrients. However, they are rarely used in functional foods. Therefore, this study aimed to enhance seaweed consumption as a functional food among Sri Lankans by developing a seaweed incorporated jam. The marine seaweed, Ulva lactuca, collected from Thalalla rocky shore area of the Southern coast of Sri Lanka, was thoroughly washed, cleaned with water several times and pre-treated with hot-water blanching. Jam was prepared by mixing Ulva with different fruit pulps, namely mango, pineapple and passion fruit peel. Preliminary sensory evaluations identified yellow passion fruit peel as the most suitable fruit pulp for incorporation with Ulva. A series of jam samples were developed using different ratios of air-dried (ADT1-4) and oven-dried (ODT1-4) Ulva powder with fruit pulp and sugar. The ratios for ADT1-4 were1:1:2, 1:2:3, 1:3:4 and 1:4:5, while those for ODT1-4 were1:8:10, 1:9:11, 1:10:12 and 1:11:13. The best ratio was selected through sensory evaluations conducted by 37 untrained members, assessing appearance, texture, taste, sweetness, aroma, spreadability, and overall acceptability using a five-point Hedonic scale. Sensory data revealed that jam prepared with oven-dried Ulva powder, yellow passion fruit peel pulp and sugar in a 1:9:11 ratio (ODT4) was significantly preferred. This jam contained 33.51% moisture, 3.89% total minerals, 0.17% crude fat, 8.61% crude fiber, 4.56% crude protein and 49.03% carbohydrate, with an energy content of 215.85 kcal/g. It also showed that a total antioxidant capacity of 61.68 mg AAE/g, 65.30 ± 1.07 °Brix and pH 6.15. Shelf-life studies indicated that the product remain consumable for over three weeks under refrigerated conditions (4 °C). In conclusion the developed seaweed-based fruit jam offers an affordable, nutrient-rich and novel confectionary product for consumers.