J. A. Robertson

Oil and water analysis of sunflower seed by near-infrared reflectance spectroscopy

The applicability of NIR for oil and moisture analyses of sunflower seed was determined using a NIR spectrocomputer system. The method was compared with the wide-line NMR method for oil analysis and with the A.O.C.S. oven method for moisture analysis. The NIR was calibrated with 120 samples for oil (96 for calibration, 24 for prediction) and 63 samples for moisture (55 for calibration, 8 for prediction). Twenty-two sunflower seed samples were analyzed for oil and moisture by NIR and by methods used by industry. The oil contents of the samples by NMR and NIR were not significantly different. The overall mean oil contents and mean of the standard deviations for the samples were: NMR, 44.2%±0.35% and NIR, 44.34%±0.74%. A significant difference was found between the moisture values obtained by the oven-drying method and NIR. The average standard deviation for moisture by NIR was 0.57% compared with 0.07% for the oven-drying method. The variability of the oil content in one of the commercial seed samples was 1.52% oil as determined by NMR and 2.52% as determined by NIR. The advantages and disadvantages of both methods are discussed.

Effect of moisture content of oil type sunflower seed on fungal growth and seed quality during storage

Oil-type hybrid sunflower seed exposed to relative humidities of 65%, 84% and 93% in environmental chambers at 10 C attained equilibrium moisture contents (mc) of 7.5±0.2%, 10.1±0.2% and 13.4±0.5% and were stored under these conditions for up to 60 weeks (wk). At 7.5% mc, germinability of seed changed very little during storage, but at 10.1% mc and 13.4% mc, germination significantly decreased during storage. At 7.5% mc, free fatty acid (FFA) levels in extracted oil did not change significantly during 60 wk of storage. However, at 10.1% mc, FFA increased significantly during 40 wk of storage and were significantly correlated with the invasion of seed by the storage fungusAspergillus (r=0.81) At 13.4% mc, FFA increased significantly during storage and were positively correlated with the invasion of seed byAspergillus andPenicillium and negatively correlated with germination percentage. Invasion of surface-disinfected seed by fungi decreased from 83% to ca 66% of total seed during storage at 7.5% mc. The predominant fungus wasAlternaria alternata (Fr.) Keissler. A previously unreportedAlternaria sp., morphologically similar toA. ricini (Yoshii) Hansford andA. macrospora, was isolated from 9% of the seed. At 10.1% mc, fungal invasion also decreased for 24 wk and then began increasing again. At 24 wk of storage,Aspergillus began invading the seed. At 13.4% mc, 100% of the seed were invaded with fungi within 8 wk of storage. TotalAlternaria rapidly decreased during storage: and after only 4 wk of storage, the seed were invaded by bothAspergillus andPenicillium. After 24 wk of storage, the predominant genus wasAspergillus, followed byPenicillim andAlternaria. Other fungi invading the seed wereCladosporium, Phoma, Mucor, Rhizopus and several unidentified fungi.

Moisture content/relative humidity equilibrium of high-oil and confectionery type sunflower seed☆

Abstract Adsorption and desorption moisture equilibrium (m.c./e.r.h.) was determined for high-oil and confectionery type sunflower seeds. The seeds were exposed to various relative humidities which were controlled with environmental chambers. The equilibration data for both seed types were determined at 10 and 20°C. The two seed types yielded almost identical adsorption and desorption moisture curves at 10°C which indicated that seed physical and chemical properties had little effect on m.c./e.r.h. at this temperature. The “hysteresis effect” was evident at 10°C, desorption equilibrium moisture levels being higher than adsorption for both seed types. There was no apparent “hysteresis effect” in seed equilibrated at 20°C. At the higher temperature, the confectionery seed equilibrated to higher moisture levels than did the high-oil type, thus hull to kernel weight ratio, hull thickness, and oil content could affect m.c./e.r.h. at 20°C

Effect of heat and frying on sunflower, oil stability

Sunflowers are one of the most important sources of vegetable oils in the world, second only to soybeans. Although in use throughout many parts of the world, sunflower seed are just now beginning to attact attention and use in the United States. Composition of the oil appears to be dependent on area of production. Sunflower oil from seed grown in northern US typically contains 70% linoleic acid. In contrast, oil from seed produced in the South generally contains 40–50% linoleic acid and is higher in mono-unsaturated fats. For most of the edible oil market, sunflower oil appears to have an advantage over most other vegetable oils. Lightly hydrogenated sunflower oil was compared with a cottonseed-corn oil mixture for frying potato chips. Organoleptic evaluation indicated that chips did not differ significantly. We also evaluated the useful life of various sunflower seed oils for deep-fat frying. Hydrogenated and unhydrogenated sunflower oils and a commercial shortening were used to deep-fry raw potatoes. A plot of the log of the Active Oxygen Method (AOM) values of the oils versus time gave a straight line, the slope of which reflects the oxidizability of the oil. Data indicated that lightly hydrogenated northern sunflower oil was much less prone to oxidation after abuse than the commercial shortening and was useful for a longer time. The southern oil deteriorated faster than the northern sunflower oil, but the two oils were processed differently. Thus, in recent work, care was taken to process both northern and southern grown sunflower seed under identical conditions. Frying studies indicated that oil from southern grown seed was more stable than that from northern seed as would be expected from their fatty acid composition.