Roasting is an important process that contribute to formation of flavour compounds in cocoa beans. Pyrazines, a by-product of Maillard reaction is one of the character impact compounds that contribute to unique cocoa flavour. Unfortunately during roasting, carcinogenic acrylamide are also produced through Maillard reaction. Therefore, this study was focussed on optimising the roasting conditions using Central Composite Design (CCD) to produce superior quality cocoa beans with high concentration of pyrazines and low concentration of acrylamide. The roasting conditions used were temperatures in the range of 110⁰C to 160⁰C and time ranging from 15 min to 40 min. Roasting conditions significantly (p
This study was conducted to develop an edible coating containing combined hydrophilic (chitosan) and hydrophobic (palm stearin) components which demonstrated gas barrier and moisture barrier properties, respectively, to prolong the post harvest life of star fruits (Averrhoa carambola L.). The emulsions of chitosan (C) and palm stearin (S) were prepared by using different ratios of C:S which were 1:0, 1:1, 1;2, 1:3, 2:1, 3:1 and 0:1. Viscosity of emulsions was studied. The physicochemical properties of coated star fruits were also evaluated in terms of weight loss, firmness, visual appearance, oxygen concentration, carbon dioxide concentration and ethylene concentration during storage at room temperature (26-28˚C) for 18 days. The results obtained showed that coating reduced weight loss, maintained firmness and appearance, slowed down the production of respiratory gases and reduced ethylene production. The most recommended coating for star fruits was C:S of 1:1 ratio as it showed good water barrier and gas barrier properties and could extend the post harvest life of star fruits up to 20 days as compared to the control samples which had a post harvest life of 12 days.
Extraction of lemongrass oleoresin was successfully optimised using Pressurised Liquid Extraction (PLE). Character impact compounds; neral, geranial and geraniol which constituted 72% oleoresin, were monitored during this optimisation study by using GCMSD. Based on maximum extraction of these compounds, the optimised operating conditions for PLE were a temperature of 167°C, a pressure of 1203 psi and a static time of 20.43 min. The quality of PLE extract were compared with conventional extraction methods, hydrodistillation and Soxhlet extraction. The proposed method was found to be better in term of quantity of the targeted character impact compounds.
The aim of this study were to find out the physicochemical characteristics of cholesterol-reduced egg yolk powder and its application in the production of mayonnaises. Cholesterol-reduced egg yolk powder (CREYP) were prepared from removal of cholesterol by formation of cholesterol:β-cyclodextrin inclusion complex. The physicochemical characteristics of CREYP and NEYP were foaming capacity (FC): 1.96%, 4%; foaming stability (FS): 96.48%, 94.55%; emulsion capacity (EC): 59.82%, 58.43% and emulsion stability (ES): 43.94%, 41.48% respectively. Whereas the viscosity of CREY, NEY and commercial mayonnaises were 8000, 4768 and 6747 cP respectively. The lightness (L*), redness (a*), yellowness (b*), saturation (C*) and hue angle (h°) values for CREYP and NEYP results showed significantly different (p>0.05) for all chroma values with CREYP showed higher L* and h° values but lower in a*, b* and C* values showing that the yellow colour of NEYP lessened. Commercial mayonnaise appeared to be lighter and less yellowish than CREY mayonnaises with L* and b* values of
commercial to CREY mayonnaises were L*: 78.34; 63.78% and b*: 8.29; 14.98% respectively. It can be concluded that CREYP can be used as replace to the NEYP and whole liquid egg yolk
with enhance nutritional values. The results obtained from this study will be very useful for producing CREYP.
The effect of microwave heating and conventional heating towards the physicochemical and
functional properties of corn and rice flour with 30% moisture content in water suspension at
temperature of 50°C and 60°C were investigated. Conventional heat treatment was carried out
at 50°C and 60°C respectively by direct heating the moisture treated flour. Microwave heating
treatment was carried out by using domestic microwave oven at 50°C and 60°C respectively.
The amylose content, particle size diameter, and gelatinization temperature are increasing in
microwave and conventional heat treated corn and rice flour. Decreasing of pasting temperature,
swelling power and solubility of all the heat-treated starches compared to control were detected.
X-ray diffraction pattern of all control and heat treated corn and rice flour exhibit typical A-type
pattern. Scanning Electron Microscopy (SEM) has revealed the heat treated corn and rice flour
showed rougher surface, porous granules and rupture granules. There are no significance effect
of temperature differences on corn and rice flour carried out at 50°C and 60°C. Evidently,
microwave heating was effective to alter the physicochemical and functional properties of corn
and rice flour.
This study investigated the effect of annealing treatment (at 50°C for 72 h) on hydrolysis of tapioca and sweet potato starches using a raw starch hydrolyzing enzyme namely STARGEN 001 (a blend from fungal α-amylase and glucoamylase) at sub-gelatinization temperature (35°C) for 24 h. The degree of hydrolysis of the starches was evaluated based on the dextrose equivalent (DE) value. The hydrolyzed starches were then characterized in terms of its morphology, swelling power and solubility, gelatinization and pasting properties, amylose content and x-ray diffraction pattern. After 24 h of hydrolysis, annealed starches were hydrolyzed to a greater degree with higher DE value compared to native starches (40% vs 33% for tapioca; and 29% vs 24% for sweet potato starch). Scanning electron microscopy (SEM) micrographs revealed a more porous granules and rougher surface in annealed starches than their native counterparts. The swelling power and solubility of annealed starches decreased significantly. Annealing was found to affect the pasting properties of the starches appreciably and increase the starch gelatinization temperature. The amylose content in hydrolyzed annealed tapioca and sweet potato starches increased while no significant changes observed in the X-ray diffraction of those starches. This study shows that the annealing treatment can be used as a way to increase the degree of hydrolysis of tapioca and sweet potato starches at sub-gelatinization temperature using a raw starch hydrolyzing enzyme.
Central Composite Design (CCD) was used to optimize roasting conditions (temperature and
time) for Arabica coffee beans. Current method of roasting was able to give good quality beans
in term of flavour but the formation of acrylamide was not studied. In this study, optimization
based on high quantity of flavour compounds (pyrazines) with low level of acrylamide resulted
in roasting temperature of 167ºC for 22 minutes. The coffee beans produced using the optimized
conditions have the following characteristics: flavour compounds: 2,3,5 trimethyl pyrazine (0.48
mg/100 g), 2,3,5,6 tetramethyl pyrazine (0.42 mg/100 g), 2 methyl pyrazine (0.25 mg/100 g)
and 2,5 dimethyl pyrazine (0.13 mg/100 g) and low concentration of acrylamide (0.11 mg/100
g) with sensory evaluation of 7.5 from 10 points. This proposed roasting condition will be very
useful for coffee manufacturers in order to produce high quality coffee beans.