Open Access Original Research Article

Functional and Physicochemical Properties of Turmeric Powder as Affected by Processing Methods

Emelike, Nkechi-Juliet Tamuno

Asian Food Science Journal, Volume 19, Issue 2, Page 1-10
DOI: 10.9734/afsj/2020/v19i230232

Turmeric rhizomes are exposed to a variety of conditions during processing such as boiling, cooking, blanching and drying before being utilized. In this study, the effect of processing methods on the functional properties and physicochemical properties of turmeric powder was investigated. Fresh turmeric rhizomes were processed into powder and five samples generated from the turmeric powder: Sample A (oven drying), sample B (blanching + oven drying), sample C (sun drying), sample D (cooking + oven drying). The processed turmeric powders were subjected to functional and physicochemical analysis using standard methods. Results obtained showed that cooking/oven drying resulted to a significant (p<0.05) improvement in the bulk density, water and oil absorption capacities and swelling power of the turmeric powders as compared to other processing methods. Dispersibility and solubility were greatly improved on sun drying/oven drying. Among the processing methods employed, blanching/oven drying exhibited significantly (p<0.05) higher colour value and curcumin content whereas decreases in TTA and pH was observed for cooked/oven dried sample. It is therefore recommended from the study that blanching/oven drying be used in the processing of turmeric powder for better nutrient retention. For better functionality of the turmeric powder, cooking/oven drying method should be employed.

Open Access Original Research Article

Proximate Composition, Phytochemical and Mineral Analysis of Cooked and Raw Walnut (Tetracarpidium conophorum)

Ojokoh Eromosele, Ojokoh Linda O., Nwachukwu Chidinma M., Omonu Richard, Eletuanya Jessica C.

Asian Food Science Journal, Volume 19, Issue 2, Page 11-17
DOI: 10.9734/afsj/2020/v19i230234

Aim: This work attempts to determine the bioactive agents’ groups probably responsible for the diverse growth characteristics and medicinal uses of (Tetracarpidium conophorum) Nigerian walnut.

Methodology: The following analyses were carried out in the study proximate, phytochemical and mineral were analyzed.

Results: The result for proximate analysis of the raw and cooked walnut seed extract contained the following parameters 42.57% and 40.91% moisture content, 20.54% and 23.03% protein, 4.51% and 4.27% Fat content, 7.26% and 7.05% crude fiber, 5.02% and 5.16% Ash content, 20.12% and 19.59% carbohydrate respectively. The phytochemical analysis results obtained revealed the presence of bioactive compounds containing 0.92 mg/100 g Tannin, 1.69 mg/100 g Saponin, 2.78 mg/100 g Flavonoid, 0.41 mg/100 g Alkaloid for cooked walnut while raw walnut contained 1.10 mg/100 g Tannin, 3.09 mg/100 g Oxalate, 2.63 mg/100 g Phytate, 3.43 mg/100 g Saponin, 3.19 mg/100 g Flavonoid and 1.34 mg/100 g Alkaloid. This study has shown the phytochemical, mineral and proximate compositions of boiled Tetracarpidium conophorum seeds.

Conclusion: The study revealed that the boiled seeds contain concentrations of alkaloids and also contain moderate quantities of tannins. These bioactive compounds could be responsible for the reported medicinal properties of Tetracarpidium conophorum seeds. This partly shows the use of this seed in herbal medicine.

Open Access Original Research Article

Antioxidant Capacity of Indigenous Root and Tuber Crops of Sri Lanka as Affected by Simple Processing

Poojanee Rupasingha, Kamani Ratnayake, Anoma Senarathne

Asian Food Science Journal, Volume 19, Issue 2, Page 18-27
DOI: 10.9734/afsj/2020/v19i230235

The indigenous root and tuber crops in Sri Lanka have not been exploited by the food industry. With a view to establish their nutritional importance and promote consumption and industry usage, this study determined the contents of selected bio active compounds and antioxidant properties in 15 root and tuber crops varieties namely, Amorphophallus paeoniifolius, Canna indica (2 Selections), Dioscorea alata (6 varieties), D. bulbifera, D. esculenta, Maranta arundinacea and Xanthosoma sagittifolium (3 varieties), both in their raw and processed (boiled) forms. Antioxidant capacity (AOC) of yams was determined by Ferric Reducing Antioxidant Power (FRAP) Assay and 2,2-diphenyl-1-picrylhydrazyl (DPPH) Radical Scavenging Assay. Total phenolics (TPC) and ascorbic acid contents (AAC) were determined by Folin-Ciocalteu method and 2,6-dichlorophenol indophenol visual titration method, respectively. Chemical analyses were performed on triplicate samples. The AOC in the raw form ranged from 56 mg TE/g dry weight (D. bulbifera) to 30 mg TE/g dry weight (M. arundinaceae) while it showed a 0.4% (D. alata ‘Raja ala’) to 45% (D. alata ‘Hingurala’) decrease when boiled. The TPC in the raw form was highest in D. bulbifera (190.5 GAE; mg/100 g) while it was lowest in D. esculenta (6 mg/100 g). Dioscorea alata ‘Jaffna Rasawalli’ showed the highest loss (95%) of phenolics when subjected to boiling. The Xanthosoma sagittifolium varieties ‘Kiri ala’ and ‘Isuru’ had the highest AAC (12 mg/100 mg) in raw form while it was lowest (2 mg/100 mg) in M. arundinaceae.   D. bulbifera and X. sagittifolium ‘Kaha kiri ala’ retained relatively higher levels of antioxidants in their boiled forms. The contents of bioactive compounds in yams tended to decrease when subject to boiling. However, the degree of loss depended on the yam variety.  Further research should focus on developing processing technologies to minimize the loss of bioactive compounds in root and tuber crops.

Open Access Original Research Article

Comparative Study of Commercial Starter and Gum-producing Lactic Acid Bacteria Isolated from Palm-sap on Yoghurt

Oniovosa Leonard Adamu- Governor, Peter Nwabueze Okolie, Emmanuel Mmmaduabuchi Ikegwu, Ifedinma Henrietta Obeten, Christiana Oluwatoyin Abiona, Sylvia Veronica Ajagugha Uzochukwu

Asian Food Science Journal, Volume 19, Issue 2, Page 28-39
DOI: 10.9734/afsj/2020/v19i230236

Yoghurt remains a fermented milk of choice globally but its desirability is limited by quality attributes and syneresis. In this study, the effect of using exopolysaccharide (EPS) producing starter cultures and EPS on the quality attribute of yoghurt produced from cow milk was examined. Two starter cultures of EPS-producing LAB were used singly and in combination in three treatments portions (YEPSLa, Lactobacillus acidophilus yoghurt; YEPSLs, Leuconostoc suionicum; YEPSLa + YEPSLs, Lactobacillus acidophilus and Leuconostoc suionicum); Yxg, Streptococcus thermophilus and Lactobacillus delbrueckii subsp. Bulgaricus to produced yoghurt while reference yoghurt (RY) was obtained from the market and refrigerated stored at 4oC. Sensory, proximate composition, textural, rheological properties and whey separation were carried out after 1 and 28 days only, while physicochemical and microbiological were analyzed after 1, 7, 14 and 28 days. No significant difference (p ˂0.05) between RY (8.60 ± 0.60), (7.21±0.10) and YEPSLa + YEPSLs (8.54 ± 0.71), (7.25 ± 0.21) in overall acceptability for day 1 and 28. Moisture (82.45 ± 0.12 - 81.31 ± 0.06%), fat (3.46 ± 0.01 - 3.42 ± 0.03%) and carbohydrate (13.05 ± 0.11 to 12.51 ± 0.10%) contents decreased while total solids (17.57 ± 0.12 - 17.97 ± 0.12%), ash (0.56 ± 0.02 - 0.57 ± 0.02%) and protein (3.74 ± 0.01 - 4.30%) contents increased respectively across the yoghurts. The result showed that the highest cohesiveness and syneresis was observed in YEPSLa + YEPSLs (27.52 ± 0.63) and commercial yoghurt (29.10 ± 0.31), the lowest in Yxg (16.71 ± 0.21) and YEPSLa + YEPSLs (21.50 ± 0.51). The highest viscosity was observed in YEPSLa + YEPSLs across the rotation speeds.  The pH and titratable acid ranged (4.28 – 4.50; 0.90 – 1.41) while the total bacteria colony count (5.5×108 – 11.0×108cfu/ml) during 28 days storage period. Overall, EPS produced by EPS-producing LAB both In-vitro and In-vivo improve texture, mouthfeel, viscosity and reduce syneresis in yoghurt. Combine cultures of Lactobacillus acidophilus and Leuconostoc suionicum and their EPSs competed favourably with conventional starter, and other stabilizing agents in cow milk yoghurt.

Open Access Original Research Article

The objective of this study was to determine the functional and pasting properties of composite flours from Triticum durum (wheat), Digitaria exilis (acha), Vigna unguiculata (cowpea) flours and Moringa oleifera leaf powder. The flour samples were mixed in a four by four factorial, in complete randomized design (CRD) to formulate the composite blends at four different levels (25, 50, 75 and 100) which gave 16 samples. The statistical analysis of data collected was used to select five (5) generally accepted composite flour samples (wheat, acha, cowpea and moringa oleifera leaf powder flours) with ratio of 100:0:0:0, 75:25:0:0, 0:50:50:0, 50:23:25:2 and 75:25:0:0, respectively. The flour samples were analyzed for functional and pasting properties using standard methods. Results of the functional properties showed that water absorption capacity of the composite flour blend ranged from 0.87-1.11g/g, bulk density 0.39-0.42 g/ml, least gelation concentration 2.00-4.00%, solubility 19.46-25.35%, wettability 2.57-4.02min, oil absorption 1.61-1.79g/g and least gelation temperature 62.00-68.50oC. The functionality of the composite flours such as water and oil absorption capacities, least gelation concentration and bulk density were improved when cowpea was incoporated into the blends than for moringa oleifera leaf powder and acha flour. On the other hand, wettability and solubility of the flour blends were improved when acha was incorporated into the blend. Results of pasting properties showed that peak viscosity ranged from 73.04-385.79RVU, trough viscosity 57.96-341.42RVU, break down viscosity 15.08-44.38RVU, final viscosity 109.54-581.58RVU, set back viscosity 51.58-240.17RVU, pasting time 5.70-6.40min and pasting temperature 50.08oC-50.35oC. These properties were shown to be higher when cowpea was incorporated into the flour blends than for moringa oleifera leaf powder and acha flour. However, pasting properties of the composite flour blends were higher than 100% wheat flour. This result therefore showed that composite flour from wheat, acha, cowpea and Moringa oleifera leaf powder has improved functionality and high pasting properties than the individual wheat flour and will serve as a useful ingredient in food formulations such as in dough, soups and baked products.