PhD

Cocoa (Theobroma cacao) is a supporting crop to farmers due to its remunerative
income, which forms the basis for one of the world’s most popular food products chocolate. The
quality of final product depends upon the fermented dried beans. High free fatty acid content is a
serious quality defect and reduces the economic value of the cocoa beans. Recently, the cocoa
trade has assumed a more scientific position and a lot of emphasis are placed on the content of
free fatty acid. A reduction in the free fatty acids level will definitely have a positive impact. As
such there is a need for the farmers to carry more intensive research and to develop and
technology for the standardisation of free fatty acid content in the processing stages of cocoa in
both primary and secondary processing.
The present study was undertaken to develop protocol for primary processing of cocoa
beans based on free fatty acid content (<1.75 %), to standardise the time and temperature of
chocolate making using machine and to evaluate the quality attributes and shelf life of the
products.
Cocoa fermentation was carried out with three different types of fermentation methods
like basket, heap and sack method for the periods of 5, 6 and 7 days of fermentation with nine
different treatments. The physico-chemical qualities of fermented cocoa beans were evaluated.
The highest (84.99%) fermentation index or cut test score was recorded in heap method at
seventh day of fermentation (T6). The highest fermentation bean recovery of 84.33% was noticed
in treatment T4 in heap method at fifth day of fermentation.
The moisture content vary from 50.40 %, 53.67% and 54.40% to 39.80%, 37.83% and
39.43% from initial to seventh day of fermentation in sack, heap and basket method respectively.
The pH of fermented beans varied from 6.11 to 4.26 in all methods. Among the
fermentation methods the maximum fat content was in heap method from initial 42.66% to
32.89%. The lipase activity, decreased with fermentation periods in all three fermentation
methods. In heap method it varied from 0.0022 to 0.0005. The heap method with seven days of
fermentation were selected to sun drying and oven drying based on the lowest free fatty acid
content (0.80%).
The bean recovery of fermented dried beans was high (41.00 %) in sun dried cocoa beans
as compared to oven dried beans (40.12 %). The free fatty acid content (1.26 %) in sun dried
cocoa beans was less compared to 1.47% in T2 (oven dried beans). The moisture content (3.76%)
and lipase activity (0.0018μ eq) was less but, the fat content and pH was high in sun dried beans.
The sun drying proved to be adaptive as free fatty acid content was lower than oven dried beans
and were below the cut off value of 1.75%.
The sun dried beans were stored in gunny bags (control), polythene covers and plastic
containers under ambient condition for a period of six months and the physico-chemical qualities
of stored cocoa beans were done initially and at an interval of one month for a duration of six
months. The highest bean recovery (98%) and least moisture content (4.22 to 4.52) was in cocoa
beans stored in plastic container at the end of sixth month of storage. The lowest free fatty acid
content of 1.68% was in cocoa beans stored in plastic container at sixth month after storage.
The stored cocoa beans in plastic container were divided into two lots, one lot was used
as such and the second lot was subjected to alkalisation. The chocolates was prepared with
alkalised and non alkalised cocoa beans in tempering and conching machine for different time
periods of 7, 9 and 11 hours at a temperature of 600C and 700. After the preparation of different
types of alkalised and non alkalised chocolates in tempering and conching machine, chocolates
were subjected to analysis of physico-chemical qualities, organoleptic evaluation and for
enumeration of microflora. The treatment T6 (Chocolate prepared at 700C for 11 hours) and T12
(700C for 11hours) had the lowest free fatty acid content of 1.67% and 1.68% and maximum
score for overall acceptability (8.89 and 8,87).
Chocolates prepared at 700C for 11 hours from alkalised and non alkalised beans were
blended with dehydrated grapes, dehydrated dates, osmodehydrated jackfruit, osmodehydrated
pineapple, badam, cashew nut, powdered dehydrated mint leaves and white pepper powder.
From the, organoleptic evaluation of different treatments, the best rated treatments from alkalised
chocolates were T3 (95 % alkalised chocolates +5% osmodehydrated jack fruit), T6 (95 %
alkalised chocolates +5% badam) and T8 (95 % alkalised chocolates +5% white pepper) and
from non alkalised chocolates the treatments T11 (95 % non alkalised chocolates +5%
osmodehydrated jack fruit), T14 (chocolate blended with 95 % non alkalised chocolates and 5%
badam) and T16 (95 % non alkalised chocolates and 5% white pepper powder) were selected,
packed in aluminium foil and stored in refrigerator for six months. Initially the lowest hardness
of 74.41N and 76.71N was recorded in controls (T0 - AC) and (T0 – NAC. The maximum energy
content of 580.15Kcal was found in treatment T5 (95 % NAC+5% B). Initially the maximum
protein content (7.74 g/100g) was noticed in treatment T2 (95 % AC+5% B) and T5 (95 %
NAC+5% B). The highest polyphenol content ranging from 0.23g/100g to 0.19g/100g was seen
in T0 (100% NAC) throughout the storage periods. A reduction in mineral contents like calcium,
phosphorus and iron content was observed in all treatments and at the end of sixth month
calcium content varied from 0.39g/100g to 0.63g/100g. An increase in lipase activity and free
fatty acid content of blended chocolates was recorded during storage and FFA was within 1.75%
up to fourth month of storage.
Based on organoleptic score, the treatment T2 (95 % AC+5% B) attained the highest rank.
The blended chocolates were evaluated for the presence of bacteria, yeast and mould initially and
monthly intervals for a period of six months, At the end of sixth month of storage the highest
bacterial count of 2.0 x 104 cfu/g was found and during sixth month of storage. The cost for
blended chocolates was varied from Rs.46.54 to Rs.50.62 / 40 g of chocolate bar. The cost of the
chocolates prepared in the present study was lesser as compared to the commercial chocolates.
The present study found that good quality, nutritious and healthy blended chocolates
using cocoa could be prepared without adding any preservatives. The blended chocolates contain
treasure of nutrients and bioactive compounds polyphenol which is essential for the growth and
development of children and also give several health benefits.