This study started with the development of juice from sapodilla (Manilkara zapota L.) fruit.
Among three formulations, sapodilla juice with the combination of 50% pure sapodilla
juice, 25oBrix, and 0.40% of titratable acidity have gained the highest score in the hedonic
sensory test, with overall acceptability ranging from “like slightly” to “like moderately”.
Formulated sapodilla juice and pure sapodilla juice were analysed for their total phenolic
and ascorbic acid contents, pH, total soluble solid and titratable acidity. The formulated
sapodilla juice has lower pH (3.35), higher titratable acidity content (0.40%) and total
soluble solid (25oBrix) than pure sapodilla juice. The total phenolic (469.82 mg GAE/L)
and ascorbic acid contents (3.60 mg/100 mL) of formulated sapodilla juice which consists
only 50% of sapodilla juice showed the lower value than the pure sapodilla juice.
Formulated sapodilla juice with lower pH will be less susceptible to enzymatic browning.
In microbiology total plate count, no colony formed on the formulated juice, whereas the
mean number of colony forming units (CFU) in pure juice was 169318.18 CFU/ml juice
stored in room temperature (28°C) for a week. These results revealed that the formulated
juice had better microbial stability than pure juice.
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.
Water kefir is the product of a brown sugar solution fermented with water kefir grains. To produce starter cultures for manufacturing commercial water kefir on an industrial scale, six lactic acid bacteria (LAB), three acetic acid bacteria (AAB), and two yeast strains have been isolated from local water kefir grains, and in vitro α-glucosidase inhibitory activity has been investigated. Five of the 11 isolates (LAB [K65, K9, K67], AAB [A5], and yeast [Y6]) showed high α-glucosidase inhibitory activity. They were then tested in an in vitro gastrointestinal tract tolerance test in which all demonstrated tolerance (40‒80% survival rate). These five strains, identified as Lactobacillus mali, Lactobacillus casei, Leuconostoc mesenteroides, Gluconobacter hansenii and Saccharomyces cerevisiae; were then used to ferment water kefir beverages. The storage stability of the fermented beverage products was analysed during 28 days of storage at 4°C by measuring α-glucosidase inhibitory activity, microbial cell viability, and microbial survival in the beverage treated with simulated gastric juice. The water kefir beverage sample containing both pumpkin purée and brown sugar fermented using all five strains (109 CFU/mL LAB strains, 107 CFU/mL yeast strain, and 106 CFU/mL AAB strain) was the most suitable formulation because it achieved >50% α-glucosidase inhibitory activity and microbial survival rates of 106‒1010 CFU/mL viable LAB cells, 106‒107 CFU/mL viable AAB cells, and 105‒108 CFU/mL viable yeast cells during storage. Therefore, these five strains have potential to act as starters in the formulation of water kefir, which is an anti-hyperglycaemic beverage that can be used to manage type-2 diabetes mellitus.
The aim of the present work was to develop legume-based kefir yogurts to replace conventional dairy yogurts that are not suitable to be consumed by vegetarians and consumers who have lactose intolerance and milk allergy. Soy and black bean milk were incubated at 15°C and 20°C for 24 h with 35 g of water kefir grains to produce kefir yogurt. The proximate composition, physico-chemical and microbiological characteristics of the yogurts were evaluated. At 20°C, soy and black bean milk produced kefir yogurts with significantly lower pH, total soluble solids, and sucrose concentration, indicating that fermentation process carried out at 20°C had higher efficiency than 15°C; meanwhile, black bean milk produced better kefir yogurts than soymilk. Black bean kefir yogurt which was fermented at 20°C had higher level of total plate count (2.05 × 107 CFU/mL), yeast and mould count (6.95 × 106 CFU/mL), and lactobacilli count (8.3
× 105 CFU/mL) as compared to other kefir yogurts. In general, 20°C produced kefir yogurt with better technological properties. Both soymilk and black bean milk were good alternative substrates for kefir yogurt production.
The effect of heat treatment below the gelatinization temperature on the susceptibility of corn, mung bean, sago, and potato starches towards granular starch hydrolysis (35°C) was investigated. Starches were hydrolyzed in granular state and after heat treatment (50°C for 30 min) by using granular starch hydrolyzing enzyme for 24 h. Hydrolyzed heat-treated starches showed a significant increase in the percentage of dextrose equivalent compared to native starches, respectively, with corn 53% to 56%, mung bean 36% to 47%, sago 15% to 26%, and potato 12% to 15%. Scanning electron microscopy micrographs showed the presence of more porous granules and surface erosion in heat-treated starch compared to native starch. X-ray analysis showed no changes but with sharper peaks for all the starches, suggested that hydrolysis occurred on the amorphous region. The amylose content and swelling power of heat-treated starches was markedly altered after hydrolysis. Evidently, this enzyme was able to hydrolyze granular starches and heat treatment before hydrolysis significantly increased the degree of hydrolysis.
The aim of this study was to develop formulations to produce lycopene nanodispersions and to investigate the effects of the homogenization pressure on the physicochemical properties of the lycopene nanodispersion. The samples were prepared by using emulsification-evaporation technique. The best formulation was achieved by dispersing an organic phase (0.3% w/v lycopene dissolved in dichloromethane) in an aqueous phase (0.3% w/v Tween 20 dissolved in deionized water) at a ratio of 1:9 by using homogenization process. The increased level of homogenization pressure to 500bar reduced the particle size and lycopene concentration significantly (p<0.05). Excessive homogenization pressure (700-900bar) resulted in large particle sizes with high dispersibility. The zeta potential and turbidity of the lycopene nanodispersion were significantly influenced by the homogenization pressure. The results from this study provided useful information for producing small-sized lycopene nanodispersions with a narrow PDI and good stability for application in beverage products.