1. Sensory evaluation of fruit leather made from kiwifruit and blackcurrant purée
Peter Feng and G.P. Savage Food Group
Score
Over all liking
Colour
Flavour
Sourness
Sweetness
Texture 1
dislike extremely
too light
too weak
bland
too soft 2
dislike very much
very light
very weak
little sour
little sweet
very soft 3
dislike slightly
slightly light
slightly weak
a bit sour
a bit sweet
slightly soft 4
neither like nor dislike
Just about right 5
like slightly
slightly dark
slightly strong
slightly sour
slightly sweet
slightly hard 6
like very much
very dark
very strong
very sour
very sweet
very hard 7
like extremely
too dark
too strong
too sour
too sweet
too hard
Introduction
Fruit leather is a snack food made from homogenized fresh fruit with additions of sugar and pectin. The mixture of fruits is carefully dried to retain important nutrients such as vitamin C, polyphenols and anthrocyanins and colour. The dried product can be stored for a long time.
Method
Five different fruit leathers were prepared from pealed kiwifruit and blackcurrant purée along with additions of sugar (Chelsea Refinery, Auckland, NZ) and high methylester, slow set pectin powder (Classic AF401, Herbsteith & Fox, Germany).
In an earlier experiment a response surface method was used to identify the optimum processing conditions (70ºC, 17 h) of the two fruit mixture and this was used as the center point of the sensory evaluation. Two further formulations of the mix were made above and below the optimum formulation. Two fruit leather products were made from kiwifruit and blackcurrant purée (Barker’s, Geraldine, NZ) alone.
The five fruit leather products were then evaluated using sensory analysis to measure the acceptability of the kiwifruit-blackcurrant fruit leather and to identify the most appreciated mixtures and processing conditions.
The five different fruit leather formulations were evaluated using 52 panelists under controlled conditions. Panelists were asked record their preferences for colour, flavour, sourness, sweetness, texture and overall liking   
Six kilograms of firm ripe green kiwifruit were obtained from a local supermarket in Christchurch, New Zealand. The fruits were sorted to remove damaged or over-ripe fruits. The green kiwifruit were stored in a 4°C chiller until used in the experiments. The other three major ingredients to be used in the trials were white sugar and blackcurrant puree (BCP) (The BCP was also stored in the chiller.
To prepare these five samples, the green kiwifruit were peeled, sliced, cored and blended into a puree together with the sugar, BCP and pectin following the formulation shown in Table 1. The blending process was carried out at high speed for 2.5 min to get a smooth mixture. The puree mixture was poured into an aluminum tray with a non-stick surface and inside dimensions of 30 cm × 20 cm × 1 cm. The puree mixture filled up the tray to a depth of 10 mm by dipping a marked wooden stick at various points of the fruit puree mixture and adjusting accordingly.
Results
Analysis of the mean scores for each of the individual attributes showed that the optimised recipe was appreciated by almost all of the panelists and was confirmed by their overall liking score for this recipe. Flavour, colour and texture of the fruit leather were the most important characteristics appreciated by the panelists. The very dark colour of the blackcurrant fruit leather was the most disliked feature. The mixture of kiwifruit and blackcurrant processed using optimum conditions produced the most acceptable colour and texture and received the highest overall liking score.
Table 3. The scores and attributes of fruit leather
Fruit
leather
Overall liking
Colour
Flavour
Sourness
Sweetness
Texture
100% kiwifruit
4.3 ± 0.2b
3.3 ± 0.2c
3.5 ± 0.2b
5.0 ± 0.2a
3.5 ± 0.2a
4.2 ± 0.1b
100% blackcurrant
2.7 ± 0.2c
6.2 ± 0.2a
4.8 ± 0.2a
5.4 ± 0.2a
2.8 ± 0.2b
4.5 ± 0.2b
Optimized recipe
4.9 ± 0.2a
3.8 ± 0.1b
4.4 ± 0.1b
3.8 ± 0.1a
4.0 ± 0.1b
Below optimized recipe
4.7 ± 0.2ab
3.7 ± 0.1b
3.8 ± 0.2a
4.3 ± 0.1b
Above optimized recipe
2.8 ± 0.2c
3.4 ± 0.2c
3.3 ± 0.2b
4.6 ± 0.2b
2.9 ± 0.2b
5.8 ± 0.2a
Table 4. Mean preference scores (± SE) for overall liking, colour, flavor, sourness, sweetness and texture for different types of fruit leathers.
Mean values within a column with the same superscript are not significantly different (P < 0.05) using a LSD test.