16 research outputs found
Effects of organic acid pretreatment on microstructure, functional and thermal properties of unripe banana flour
Starch availability has been implicated in unripe
matured banana (Musa species), which when processed
yields flour suitable for application in low gluten and
composite wheat formulations. Unripe Musa species:
Williams, Luvhele, Mabonde and Muomva-red obtained
from fruit bunch were pretreated with ascorbic, citric and
lactic acids, processed into 50 g of flour and characterised
for their functional and thermal properties. Scanning
electron microscope of unripe banana flour (UBF) showed
varying micrographs of flour, with polygonal for Luvhele,
oval for Mabonde, elongated for Muomva-red and between
polygonal and spherical for Williams. The bulk density of
UBF samples was within the range of 0.66–0.84 g/mL for
all organic acid pretreatment while citric acid pretreated
UBF had the least browning index. Significant difference
(p\0.05) was recorded in swelling power with no significant
difference in water solubility index except for
Mabonde UBF. Thermal properties showed single
endothermic transition for all UBF samples at various
pretreatment concentration. The onset temperature (To) of
UBF ranges from 49.82 to 65.59 C, peak temperature (Tp)
from 60.11 to 76.71 C, conclusion temperature (Tc) from
70.36 to 94.16 C and enthalpy of gelatinization (DH) from
2.61 to 32.24 J/g. Short amylopectin chains present in
starch of UBF was attributed to low To, Tp, Tc and
DH values recorded for Mabonde cultivar, while the contribution
of heat-moisture treatment rather than organic
acid pretreatment of UBF samples was attributed to different
gelatinization and transition temperatures recorded
for all cultivars examined.TAA from the University of Venda (UNIVEN) Research and Publication Committee Fund (SARDF/13/FST/01) and the Work Study Programme of the UNIVEN, South Afric
Improving Carob Flour Performance for Making Gluten-Free Breads by Particle Size Fractionation and Jet Milling
Many different raw materials have been proposed for producing nutritious gluten-free breads, but rarely, there is a parallel analysis of the effect of physical treatment on those ingredients. The aim of this study was to incorporate carob flour fractions of varying particle size on rice gluten-free breads prepared with carob/rice (15:85) flour blends. Carob flour particle size was controlled by fractionation or jet milling application. Quality features of gluten-free breads containing carob flour and commercially available gluten-free breads were compared. Carob flour addition led to breads with improved colour parameters, crumb structure, retarded firming and lower moisture loss compared to rice bread. Further improvement in specific volume, crumb hardness, protein and ash content and estimated glycaemic index (eGI) could be obtained by a careful selection of the particle size distribution of the carob flour. Carob breads prepared either with the coarsest or the finest fraction prepared using jet milling led to end products with the highest specific volume (≈2.2 g/cm3) and the lowest crumb hardness (≈5.5 N), although they had lower specific volume and harder crumbs than breads from commercial blends (≈3–4 g/cm3, 0.6–3.8 N). Nevertheless, rice-based bread made with the finest carob flour was superior considering its slower firming, protein content and lower eGI. The incorporation of carob flour obtained by jet milling in rice-based gluten-free breads led to end products with quality characteristics and sensory acceptance resembling commercial breads and high nutritional value.Financial support of the Spanish Ministry of Economy and Competitiveness (Project AGL2014-52928-C2-1-R) and the European Regional Development Fund (FEDER)Peer reviewe
Modelling the Effects of Debranching and Microwave Irradiation Treatments on the Properties of High Amylose Corn Starch by Using Response Surface Methodology
Response surface methodology was applied to determine the effects of pullulanase debranching, microwave irradiation time (2-4 min) and power (20-100%) on resistant starch (RS) formation and in-vitro glycemic index (GI) values in high amylose corn starch, Hylon VII. Starch:water (1:10) suspensions were cooked and autoclaved, debranched with pullulanase (1000 PUN/g; 1500 U/kg starch) at 60 A degrees C and then different microwave-storing cycles and drying (oven or freeze drying) processes were applied. In order to describe the relationship between the dependent and independent variables (microwave power and irradiation time), the response values were fitted by first order polynomial regression models. Significance analysis showed that microwave irradiation time had significant effect on RS content and GI value of the samples treated with one cycle of microwave-storing prior to freeze-drying. Microwave power had significant factor on the GI value of the samples that were oven-dried after one cycle of microwave-storing. Solubility and water binding capacity values of all heat treated samples were higher than those of native starch. On the other hand, RVA viscosity values were lower than native starch for oven-dried samples. Water binding capacity, solubility and final viscosity values of the freeze-dried samples were higher than those of oven-dried ones