Cashew Processing and Quality Indices
Date
2000-08
Authors
Journal Title
Journal ISSN
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Publisher
University of Ghana
Abstract
Cashew is made up of the nut attached to the apple (false fruit) both of which have nutritional
significance and economic value. Evaluating the changes that occur during growth and
maturation as well as processing will help to optimize quality. This is what the study
involved.
Compositional and physical changes were monitored in six cultivars of cashew (apple and
nut). Local cashew trees were selected randomly after flowering. Collection of samples
commenced after fruit set and at weekly intervals till 8 weeks (maturity). Physical analysis
included weight (whole cashew, nut, apple, cashew nut, nut kernel and shell) and size (length
of apple and nut, thickness and width of nut and top and bottom diameter of apple).All the physical indices of apples showed a single phase of continuous increase after fruit set
reaching maximum values at 8 weeks. Weight and length of apples increased from 0.31 ±
0.01-68.56 ± 0.32g and 0.69 ± 0.03-5.82 ± 0 .12cm respectively. Unlike the apples, the growth
pattern of nuts occurred in two stages. There was initial rapid increase with the attainment
of maximum values at 4 and 5 weeks after which a decrease occurred. At 8 weeks the nuts
attained a proportion o f their maximum values i.e. weight (4.89 ± 0.09-6.33 ± 0.15g) and
length (2.41 ± 0.01- 2.90 ± 0.02cm). Growth time was more strongly correlated with the
physical indices of apples.Similar trends of total sugar accumulation occurred in both the apples and cashew nut kernels.
Increases were observed with maturation and optimal values of 10.01-10.85% for apple and
5.04-6.14% for the kernels was observed at 8 weeks. Increase in the ash (0.48-2.70g/l OOg),
total solids (27.57-80.28%), fat (1.81-39.42g/100g) protein (0.95-20.93g/100g) and mineral
(e.g K:20.81 -491.3 5mg/1 OOg) contents occurred in the kernel from fruit set to 8 weeks. These
increases were rapid after 4 weeks of growth. The apples increased in moisture (69.42-
86.95%), vitamin C (72.51-225.9-49mg/100g) and titratable acidity during growth and
maturation (Fruit set-8 weeks). All the above constituents in the cashew kernel and apple
were at maximal values by the eighth week of growth. The nut kernel generally decreased in
moisture (73.46-19.46%) with growth. pH (4.11-3.65) of apples generally decreased whilst
total solids (30.58-13.05%)ash(0.84-0.45g/100g)andmineral(e.g.P:243.04-128.21mg/100g)contents decreased continuously from fruit set to 8 weeks. Pectin and tannin contents of the
apples increased to maximum values generally between 3-5 weeks, after which depletion
occurred. At 8 weeks, minimum values of pectin (0.59-0.76%) and tannin (0.19-0.40 g/1 OOg)
was attained.
Changes in chlorophyll (total chlorophyll, chlorophyll a & b) and absorption spectra of two
apple cultivars were monitored during growth. Chlorophyll contents of the apples (e.g. total
chlorophyll: 15.05-1,04mg/l OOg) decreased with maturation (fruit set to 8 weeks). The same
occurred for the number of peaks (5-1) in the absorption spectra.
Processing methods, peeling, steaming and peeling before steaming were applied to the
apples. Quality indices o f the resultant juice was analyzed by objective and sensory methods
and during one week of storage. pH, acidity, vitamin C and tannin contents of apples were
significantly affected by the methods of processing (P < 0.05). Peeling before steaming was
most effective in reducing tannin contents. Apart from tannin, vitamin C (266.42-
155.42mg/100g) and pH (4.41-4.08) decreased whilst titratable acidity increased during
storage. Sensory analysis included sweetness, colour, flavour, astringency intensities, and
overall acceptability. Panelists generally preferred and most accepted the quality indices of
juices obtained from steamed (SAJ and PSAJ) apples as compared to unsteamed ones (WAJ
and PAJ).
Description
Thesis (MPhil) - University of Ghana, 2000