3 research outputs found
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Effects of heat-moisture treatment on the thermal, functional properties and composition of cereal, legume and tuber starches: a review
Several methods are currently employed in the modification of starch obtained from different botanical sources. Starch in its native form is limited in application due to retrogradation, syneresis, inability to withstand shear stress as well as its unstable nature at varying temperatures and pH environment. Modification of starch is therefore needed to enhance its food and industrial application. A primary and safe means of modifying starch for food and industrial use is through hydrothermal methods which involves heat-moisture treatment and annealing.
Heat-moisture treatment (HMT) is a physical modification technique that improves the functional and physicochemical properties of starch without changing its molecular composition. Upon modification through HMT, starches from cereals, legumes and tuber crops serve as important ingredients in diverse food, pharmaceutical and industrial processes. Although changes in starch initiated by HMT have been studied in starches of different plant origin, this work further provides insight on the composition, thermal and functional properties of heat-moisture treated starch obtained from cereals, legumes and tuber crops
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Influence of head-moisture treatment on functional, colour and thermal properties of bambara ground-nut starch
MSCFSTDepartment of Science and TechnologyHeat-moisture treatment (HMT) is a physical modification that alters the physicochemical
properties of starch without changing its molecular structure. The objective of the study was to
investigate the influence of HMT on the functional, colour and thermal properties of bambara
groundnut (BG) starch. A central composite rotatable design comprising two independent factors
(temperature and time) was used for the study. The central composite rotatable design was
generated using Design-Expert software version 8.0.1.0. Bambara starch extraction was done by
milling BG into flour (5 Kg), suspension in 15 L, 0.3% sodium hydroxide and centrifugation
followed by washing using distilled water. The starch was then HMT treated in an air oven at 80 -
120 °C for 30 - 90 min under 15 % moisture content (MC) (HMT 15), 25% MC (HMT 25) and 35%
MC (HMT 35). The highest L* and WI values for HMT treated BG starch were observed at HMT
80 °C for 30 min under 15% MC; 100 °C for 60 min (25% MC); and 100 °C for 17.57 min (35%
MC) while the lowest was observed in HMT 100 °C for 102.43 min (15% MC); 120 °C for 90 min
(25% MC); and 120 °C for 90 min (35% MC). In HMT 15-BG starch, the gelatinisation parameters
onset (To), peak (Tp) and concluding temperature (Tc) of the samples decreased as treatment time
and temperature increased whereas gelatinisation enthalpy of BG starch increased with increase
in HMT treatment temperature and time. In HMT 25-BG starch Tp, and gelatinisation enthalpy of
the starch increased with increase in HMT treatment temperature and time. While in HMT 35-BG
starch, To, Tp, Tc and gelatinisation enthalpy of the starches decreased with increase in HMT
treatment temperature and time. In HMT 15-BG starch, the water absorption capacity (WAC),
solubility and swelling power (SP) decreased as treatment time and temperature increased while
oil absorption capacity (OAC) of the starch increased with increase in HMT treatment temperature
and time. In terms of HMT 25-BG starch, the WAC and OAC increased as HMT treatment time
and temperature increased while SP and solubility of the starch decreased with increase in HMT
treatment temperature and time. In HMT 35-BG starch, OAC, solubility and SP decreased as
treatment time and temperature increased while WAC of the starch increased with increase in
HMT treatment temperature and time. The optimum HMT conditions for BG starch were found to
be 80 °C for 30 min (HMT 15), 105.74 °C for 30 min (HMT 25), and 113.16 °C for 30 min (HMT
35). Desirability of the obtained optimum conditions were 0.63 (HMT 15), 0.56 (HMT 25) and 0.64
(HMT 35). Information obtained from scanning electron micrograph indicates oval and round
shape for bambara starch granules, with varying sizes. The range of the granule size width was
4.2 – 4.7 mm and 10 μm for length. The modified starches showed some changes in granule
morphology as they seem to disintegrate with application of HMT. Unmodified and HMT - BG
starches showed characteristic FTIR bands linked with common starches. All the samples
displayed complex vibrations in the region below 1000 cm-1 due to the skeletal vibrations of the
glucose pyranose ring. Statistical analysis on colour, thermal and functional properties of HMT
15-BG, HMT 25-BG and HMT 35-BG starch showed that effects of temperature and treatment
time had no significant (p ≥ 0.05) effect on these properties of HMT-BG starch. However,
treatment time had a significant linear effect (p ≤ 0.05) on swelling power, for HMT 15-BG starch.
In HMT 35-BG starch, WAC was significantly affected by quadratic effect of temperature and time
while solubility was significantly affected by linear effect of time and quadratic effect of
temperature.NR
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Optimisation of the techno-functional and thermal properties of heat moisture treated bambara groundnut starch using response surface methodology
This work optimised the techno-functional and thermal properties of heat moisture treated Bambara groundnut starch (BGS). A central composite rotatable design (Design-Expert software v8.0.1.0) comprising two independent factors of temperature and time was used. Extracted BGS were subjected to heat-moisture treatment (HMT) at 80–120 °C for 30–90 min at different moisture levels of 15% (HMT 15-BGS), 25% (HMT 25-BGS) and 35% (HMT 35-BGS). The optimum HMT conditions for BGS were found to be 80 °C for 30 min (HMT 15), 105.74 °C for 30 min (HMT 25), and 113.16 °C for 30 min (HMT 35). The desirability values of the obtained optimum conditions were 0.63 (HMT 15) and 1.00 (HMT 25 and 35). In HMT 35-BGS, water absorption capacity was significantly affected by the quadratic effect of temperature and time. In contrast, solubility was significantly affected by the linear effect of time and the quadratic effect of temperature. Temperature and treatment time had no significant effect (p ≥ 0.05) on the differential scanning calorimetry thermal properties of HMT 15, 25 and 35-BGS. Scanning electron micrographs of optimised BGS showed round and oval-shaped starch granules ranging from 4.2 to 4.7 mm (width) and 10 μm for length. Unmodified and optimised HMT–BGS showed characteristic FTIR bands linked with common starches. All BGS samples displayed multiple vibrations in the region below 1000 cm−1 due to the skeletal vibrations of the glucose pyranose ring