Margaret Slavin

Fatty acid composition, oxidative stability, antioxidant and antiproliferative properties of selected cold-pressed grape seed oils and flours

Cold-pressed chardonnay, muscadine, ruby red, and concord grape seed oils and their defatted flours were studied for their fatty acid composition, oxidative stability and antioxidant and antiproliferative activities. The phenolic profiles of the seed flours were also measured. The most abundant fatty acid in the oils was linoleic acid, ranging from 66.0g/100g of total fatty acids in ruby red seed oil to 75.3g/100g of total fatty acids in concord seed oil. The oils were also high in oleic acid and low in saturated fat. Ruby red grape seed oil recorded the highest oxidative stability index of 40h under the accelerated conditions. Total phenolic content (TPC) was up to 100 times lower in the oils than in the flours. Lutein, zeaxanthin, cryptoxanthin, β-carotene, and α-tocopherol levels were also measured. DPPH radical-scavenging capacity ranged from 0.07 to 2.22mmol trolox equivalents (TE)/g of oil and 11.8 to 15.0mmol TE/g of flour. Oxidative stability of menhaden fish oil containing extracts of the seed flours was extended by up to 137%. HPLC analysis was conducted to determine the levels of free soluble, soluble conjugated and insoluble bound phenolics in the seed flours. The phenolic compounds analyzed included catechin, epicatechin, epicatechin gallate, quercetin, gallic acid, and procyanidins B1 and B2. Antiproliferative activity was tested against HT-29 colon cancer cells. All of the seed flours and muscadine seed oil registered significant (P<0.05) inhibition of cancer cell growth. The results from this study demonstrate the potential of developing value-added uses for these seed oils and flours as dietary sources of natural antioxidants and antiproliferative agents for optimal health.

Antioxidant properties and phytochemical composition of China-grown pomegranate seeds

Four cultivars of Shanxi-grown pomegranate seeds were investigated for their phytochemical composition and antioxidant properties. Pomegranate seed oils were extracted and analysed for their fatty acid profiles, and tocopherol and carotenoid contents. The defatted flours were extracted with 50% acetone or 80% methanol, and evaluated for levels of phenolics, flavonoids and proanthocyanidins, and scavenging capacities against DPPH and ABTS+ and their ferric ion reducing abilities. Pomegranate seed oil was rich in punicic acid (73.5-78.8g/100g oil) and total tocopherols (5.3-12.0μmol/g). The 50% acetone and 80% methanol were appropriate solvents for extraction of total phenolic and total flavonoid, respectively. The four cultivars were significantly different in levels of phenolics, flavonoids, proanthocyanidins and their antioxidant properties (P<0.05), generally flowing an order: Suanshiliu>Tianhongdan>Sanbaitian≈Jingpitian. This study will assist in the cultivar selection of the above pomegranate seeds for commercial production to meet the market demand.

A single extraction and HPLC procedure for simultaneous analysis of phytosterols, tocopherols and lutein in soybeans

A saponification/extraction procedure and high performance liquid chromatography (HPLC) analysis method were developed and validated for simultaneous analysis of phytosterols, tocopherols and lutein (a carotenoid) in soybeans. Separation was achieved on a phenyl column with a ternary, isocratic solvent system of acetonitrile, methanol and water (48:22.5:29.5, v/v/v). Evaporative light scattering detection (ELSD) was used to quantify β-sitosterol, stigmasterol, campesterol, and α-, δ- and γ-tocopherols, while lutein was quantified with visible light absorption at 450 nm. Peak identification was verified by retention times and spikes with external standards. Standard curves were constructed (R(2)>0.99) to allow for sample quantification. Recovery of the saponification and extraction was demonstrated via analysis of spiked samples. Also, the accuracy of results of four soybeans using the described saponification and HPLC analytical method was validated against existing methods. This method offers a more efficient alternative to individual methods for quantifying lutein, tocopherols and sterols in soybeans.