Yogeshini Ramakrishnan

Combination of saponification and dispersive liquid-liquid microextraction for the determination of tocopherols and tocotrienols in cereals by reversed-phase high-performance liquid chromatography.

A simple sample preparation technique coupled with reversed-phase high-performance liquid chromatography was developed for the determination of tocopherols and tocotrienols in cereals. The sample preparation procedure involved a small-scale hydrolysis of 0.5g cereal sample by saponification, followed by the extraction and concentration of tocopherols and tocotrienols from saponified extract using dispersive liquid-liquid microextraction (DLLME). Parameters affecting the DLLME performance were optimized to achieve the highest extraction efficiency and the performance of the developed DLLME method was evaluated. Good linearity was observed over the range assayed (0.031-4.0μg/mL) with regression coefficients greater than 0.9989 for all tocopherols and tocotrienols. Limits of detection and enrichment factors ranged from 0.01 to 0.11μg/mL and 50 to 73, respectively. Intra- and inter-day precision were lower than 8.9% and the recoveries were around 85.5-116.6% for all tocopherols and tocotrienols. The developed DLLME method was successfully applied to cereals: rice, barley, oat, wheat, corn and millet. This new sample preparation approach represents an inexpensive, rapid, simple and precise sample cleanup and concentration method for the determination of tocopherols and tocotrienols in cereals.

Tocopherol and tocotrienol contents of different varieties of rice in Malaysia

BACKGROUND The present study examined the contents of tocopherols and tocotrienols and their distribution in 58 different varieties of whole rice cultivated in Malaysia. The analytical method used was saponification of samples followed by dispersive liquid-liquid microextraction and reverse phase high-performance liquid chromatography. RESULTS The total vitamin E contents of different varieties of whole rice ranged between 19.36 and 63.29 mg kg⁻¹. Contents of vitamin E isomers varied among rice varieties both within and between grain color groups. Black-pigmented rice showed significantly higher mean contents of α-tocopherol, β-tocopherol and α-tocotrienol than non-pigmented rice and red-pigmented rice. Red-pigmented rice had significantly lower mean contents of γ-tocotrienol and total vitamin E than non-pigmented rice. The mean contents of δ-tocotrienol and total vitamin E in non-pigmented rice, however, were similar to those in black-pigmented rice. γ-Tocotrienol was the predominant form of vitamin E isomer in all analyzed varieties. The Pearson correlations among vitamin E isomers and total vitamin E content of whole rice were also studied. CONCLUSION This study provides information on vitamin E content of different rice varieties that would be beneficial for decision making in genetic breeding of bioactive compound-rich rice varieties.

Functional and Preliminary Characterisation of Hydrocolloid from Tamarillo (Solanum betaceum Cav.) Puree

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.

REVIEW: Properties of Cereal Brans: A Review

ABSTRACT Cereal brans are functional ingredients with high nutritive value and enormous health properties. Cereal brans have not been fully utilized in food systems despite their health benefits. This review presents an overview on the physical, chemical, microbiological, functional, and sensory properties of cereal brans for possible comparisons and selection to enhance the utilization of this underutilized milling fraction.

Fractionation, physicochemical, and structural characterization of winged bean seed protein fractions with reference to soybean

ABSTRACT Proteins from defatted flour winged bean seed (Psophocarpus tetragonolobus) were sequentially fractionated with reference to soybean seed (Glycine max) using distilled water, 25 g/kg sodium chloride solution, 0.1 M NaOH, and 70% alcohol and subjected to physicochemical, functional, and structural analysis. Winged bean seed had globulin (31.94%) and albumin (26.46%), with denaturation temperatures (Td) of 92.82 and 82.76°C, and surface hydrophobicities (SHs) of 214.51 and 189.32, respectively, whereas soybean seed had 34.95% globulin and 32.82% albumin, with respective Td of 81.68 and 90.63°C, and SH of 210.80 and 204.66. This indicates that winged bean albumin could perform better at water/oil interface in an oil-in-water emulsion system because of it higher hydrophobicity, although soybean albumin had higher extraction rate. Both legumes’ proteins showed comparable gelation when employed for their gelling ability to form three-dimensional network in food systems. Soybean proteins had significantly (P < 0.05) higher foaming capacities, but winged bean proteins foams were more stable and soluble over broad pH, good for manufacture of ice cream and protein beverages, respectively. Though β-sheets and β-turns were the major secondary structures of both protein fractions, soybean albumin had significantly (P < 0.05) higher β-sheets than winged bean albumin, whereas winged bean globulin and glutelin had higher content of β-sheets than corresponding soybean fractions. The low amounts of β-sheets in the winged bean albumin and soybean globulin could render them more digestible than the corresponding soybean and winged bean protein fractions. Abbreviations: WB: Winged bean; SB: soybean; Td: denaturation temperature; SH: surface hydrophobicity; SH: surface hydrophobicity; W-ALB: winged bean albumin; W-GLO: winged bean globulin; W-GLU: winged bean glutelin; W-PRO: winged bean prolamin; W-ISO: winged bean isolate; S-ALB: soy albumin; S-GLO: soy globulin; S-GLU: glutelin; S-ISO: soy glutelin and S-PRO: soy prolamin.