2. Materials and methods
2.1. Sample collection
Fresh firmly ripe banana, pineapple, and apple fruits and the lemon used as a preservative and to reduce browning, in this study were obtained from Umuahia main market, Umuahia, Abia State, Nigeria. Fruit leather preparation was carried out at the food processing laboratory of Food Science and Technology Department, Michael Okpara University of Agriculture, Umudike Umuahia, Abia State, Nigeria.
2.2. Preparation of the mixed fruit leather
The mixed fruit leather was prepared using the Maskan et al. (2002) method with little modification. The fruits (Banana, Pineapple and Apple) were selected, sorted, washed, weighed and manually peeled with a stainless steel knife. They were then cut and sliced into pieces and dipped in lemon juice for 5–10 min. The pieces were transferred to a 60–70% sugar solution, boiled for 10–15 min and allowed to soak for up to 18 h. Up to half the water in the fruit is removed. The fruit pieces are then pulped, spread on aluminum foil and dried in an oven at a temperature, between 60 and 80 °C for 10 h. The fruit leather is cut into small sizes, sprinkled with sugar and packed in a cool and dry place, away from sunlight, until the leather pieces were required for analysis (Fig. 1).
The three fruits were combined in different proportions for the leather production and coded as follows:
Sample 443 – (20% banana: 40% pineapple: 40% apple)
Sample 314 – (60% banana: 20% pineapple: 20% apple)
Sample 819 – (40% banana: 40% pineapple: 20% apple)