Pectin from different fractions of dragon fruit (Hylocereus polyrhizus) peel was extracted using 1% citric acid and the physico-chemical characteristics of the pectin were studied. The highest pectin yield (26.38% on dry weight basis) was obtained from fresh inner layer of the peel when extraction was carried out at temperature: 73 °C, time: 67 min, pH: 2.03, and sample to citric acid ratio: 1:4 (w/v). The pectin also demonstrated the highest degree of esterification (63.74%) when compared with pectin from other fractions of the dragon fruit peel investigated in this study. The calculated degree of esterification confirmed that the extracted pectin is a high methoxyl pectin. The molecular weight of the pectin determined using size exclusion chromatography was 0.88 × 105 Da. Monosaccharide composition determined using high performance liquid chromatography revealed that the pectin was predominantly constituted of galacturonic acid (39.11%), followed by moderate concentrations of mannose, rhamnose, galactose, glucose and minor amounts of xylose and arabinose. The pectin exhibited Newtonian behaviour at concentrations of 0.5% and 1.0%, and pseudoplastic behaviour at concentrations of 2.0% and 3.0%. Although the viscosity of the dragon fruit peel pectin was lower than that of commercial apple and citrus pectins, it can be used as a functional and health ingredient in low viscous foods and beverages.

Tamarillo (Solanum betaceum Cav.) is an underutilised fruit in Malaysia. The fruit, however, contains good proportions of soluble fibre, protein, starch, anthocyanins and carotenoids. Amongst the fruits, only tamarillo mesocarp contains both polar (anthocyanins) and non-polar (carotenoids) pigments. The ability to retain both polar and non-polar pigments in the mesocarp could be related to the unique properties of its hydrocolloids. To understand the pigment-hydrocolloid interaction in the fruit, information on the physicochemical characteristics of the hydrocolloids is required. Therefore, hydrocolloids from the anthocyanin-rich seed mucilage fraction of the tamarillo and its carotenoid-rich pulp fraction were extracted and characterised. Water and 1% citric acid were used to extract the seed mucilage hydrocolloid while 72% ethanol and 20mM HEPES buffer were used for pulp hydrocolloid extraction. Seed mucilage hydrocolloid was primarily composed of arabinogalactan protein-associated pectin whereas pulp hydrocolloid was composed of hemicellulosic polysaccharides with some naturally interacting proteins and neutral polysaccharides.

Hydrocolloid from tamarillo (Solanum betaceum Cav.) puree was extracted using water and characterised for the first time. Proximate compositions of the extracted hydrocolloid were also determined. Functional characteristics such as water-holding capacity, oil-holding capacity, emulsifying activity, emulsion stability, foaming capacity and stability of the hydrocolloid were evaluated in comparison to that of commercial hydrocolloids. Its functional groups and degree of esterification were determined using Fourier Transform Infrared (FT-IR) spectroscopy. Monosaccharide profiling was done using reverse-phase high pressure liquid chromatography (RP-HPLC). Screening of various fruits for high hydrocolloid yield after water extraction resulted in tamarillo giving the highest yield. The yield on dry weight basis was 8.30%. The hydrocolloid constituted of 0.83% starch, 21.18% protein and 66.48% dietary fibre with 49.47% degree of esterification and the monosaccharides identified were mannose, ribose, rhamnose, galacturonic acid, glucose, galactose, xylose and arabinose. Higher oil-holding capacity, emulsifying activity and emulsion stability compared to commercial hydrocolloids propose its possible application as a food emulsifier and bile acid binder. Foaming capacity of 32.19% and good foam stabilisation (79.36% of initial foam volume after 2 h of foam formation) suggest its promising application in frothy beverages and other foam based food products. These findings suggest that water-extracted tamarillo hydrocolloid can be utilised as an alternative to low methoxyl pectin.

Hydrocolloids were extracted from seed mucilage and the pulp fractions from red tamarillo (Solanum betaceum Cav.) mesocarp, and characterisation of their techno-functional properties and in vitro bile acid-binding capacities was performed. The seed mucilage hydrocolloids that were extracted, using either 1% citric acid (THC) or water (THW), had a good foaming capacity (32-36%), whereas the pulp hydrocolloids that were extracted, using 72% ethanol (THE) or 20mM HEPES buffer (THH), had no foaming capacity. The pulp hydrocolloid, however, possessed high oil-holding and water-holding capacities in the range of 3.3-3.6 g oil/g dry sample and 25-27 g water/g dry sample, respectively. This enabled the pulp hydrocolloid to entrap more bile acids (35-38% at a hydrocolloid concentration of 2%) in its gelatinous network in comparison to commercial oat fibre and other hydrocolloids studied. The exceptional emulsifying properties (80-96%) of both hydrocolloids suggest their potential applications as food emulsifiers and bile acid binders.

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Available online A B S T R A C TTwo types of hydrocolloids in two distinct zones of red tamarillo (Solanum betaceum Cav.) mesocarp were resistant to digestive enzymes and exhibited different in vitro prebiotic activities. Low molecular weight tamarillo seed mucilage hydrocolloid that was extracted using 1% citric acid or water encouraged the growth of bifidobacteria and lactobacilli more than the high molecular weight tamarillo pulp hydrocolloid that was extracted using 20 mM HEPES buffer or 72% ethanol. The seed mucilage hydrocolloid was also better in reducing the number of pathogenic bacteria than the pulp hydrocolloid. In vitro fermentation of seed mucilage hydrocolloid resulted in higher production of acetate whereas propionate was formed in higher concentration from fermentation of the pulp hydrocolloid. Both hydrocolloids can produce higher amounts of butyrate than inulin and oligofructose during the fermentation. Tamarillo hydrocolloids can act as prebiotics.

Introduction: Rice noodles are widely consumed as a staple food in Asia. The main ingredient of rice noodle is polished white rice flour which lacks in nutritional components. Substitution of white rice flour with brown rice flour often results in noodles with better nutrient content but less favourable for cooking, textural and sensory characteristics. Thus, this study aimed to develop and characterise brown rice noodles substituted with mung bean powder at the level of 5% (g/100 g) and compared with other formulations. Methods: Four formulations of rice noodles were prepared using: a. 100% white rice flour; b. 100% brown rice flour; c. white rice flour with 5% mung bean powder; and d. brown rice flour with 5% mung bean powder. The rice noodles were produced by conventional extrusion method and evaluated for their proximate composition, cooking qualities and sensorial properties. Results: The results of proximate analysis indicated that protein (8.70g/100 g), dietary fibre (3.10g/100 g), ash (1.50g/100 g) and fat (2.40g/100 g) contents were significantly (p<0.05) higher in mung bean powder substituted brown rice noodles than that of white rice noodles (control). The blending of mung bean powder with brown rice flour had significantly reduced noodle cooking time and cooking loss. The sensory evaluation revealed that mung bean powder substituted brown rice noodles had similar consumer preference to control sample. Conclusion: The blending of mung bean powder with brown rice flour had substantially improved the nutritional value and cooking qualities of the brown rice noodles while maintaining consumer acceptability.

PurposeDeep-fried banana (Musa spp.) fritters is one of the frequently consumed fruit based snacks in Southeast Asian countries despite its substantial amount of oil content. Consistent with the demand for low fat food with maintained palatability, this study aimed to determine the quality of banana fritters as affected by batter system containing selected hydrocolloids such as pectin (PCN), whey protein isolate (WPI) and soy protein isolate (SPI).Design/methodology/approachBanana fritter batters were prepared with individual addition of 2% PCN (w/w), 10% WPI (w/w), 10% SPI (w/w), combination of 2% PCN and 10% WPI, combination of 2% PCN and 10% SPI and control (without hydrocolloid addition). Batter viscosity (Pa.s) and batter pick-up (%) were determined. Banana fritters were analysed for moisture and fat contents, moisture loss, colour, hardness and sensory characteristics.FindingsHydrocolloid addition in the batter system resulted in a higher batter pick-up and viscosity in comparison to control batter system. Moisture loss from banana fritters with batter formulation of 2% PCN and 10% SPI was the lowest while the reduction in oil content (55%) was the highest. Banana fritters with inclusion of hydrocolloids in the batter formulation were equally accepted as the control sample by the sensory panelists with a score range between 6 and 7 for most of the sensory attributes evaluated except for oiliness.Originality/valueApplication of PCN and SPI in batter system to develop banana fritters with low oil content, moist fruit core and crunchy crust is reported for the first time. Batter premix containing PCN and SPI can be produced for fresh and frozen fritters preparation.