N.A.M. Eskin

Chemical and physical properties of yellow mustard (Sinapis alba L.) mucilage

Abstract The yield of crude mucilage (CM) obtained from yellow mustard ( Sinapis alba , L.) was 5% of the total seed weight. CM was separated into a water-soluble fraction (WS, 55·6%) and a water-insoluble fraction (WI, 38·8%). Proximate analysis of CM and its fractions revealed carbohydrates as the major component (80–94%) with ash (1·7–15·0%) and protein (2·2–4·4%) as minor constituents. Glucose (22–35%) was the major monosaccharide present followed by galactose (11–15%), mannose (6·0–6·4%), rhamnose (1·6–4·0%), arabinose (2·8–3·2%) and xylose (1·8–2·0%). All mucilage fractions exhibited interfacial activity and shear thinning behaviour typical of xanthan gum dispersions. Of the mucilage fractions studied, the WS fraction was least affected by pH, temperature and solutes (NaCl, sucrose).

Characterization of quinoa (Chenopodium quinoa) lipids.

Abstract Lipids isolated from quinoa seed and seed fractions were characterized for lipid classes and their fatty acid composition. Quinoa seed lipids contained the largest amount of neutral lipids among all the seed fractions analyzed. A very high content of free fatty acids was detected in whole quinoa seed and hulls, accounting for 18·9 and 15·4% of total lipids, respectively. Triglycerides were the major fraction present and accounted for over 50% of the neutral lipids. Diglycerides were present in whole seed and contributed 20% of the neutral lipid fraction. Of the phospholipids examined, lysophosphatidyl ethanolamine, was the most abundant and made up 45% of the total polar lipids. Phosphatidyl choline was the second largest phospholipid component and contributed 12% of whole seed phospholipids. Considerable variation in phospholipids was evident between the different fractions. The overall fatty acid composition of whole quinoa seeds, however, was similar to that reported for other cereal grains, with linoleic, oleic and palmitic acids as the major acids present.

Performance of Canola and Soybean Fats in Extended Frying

Abstract The effects of extended deep frying on chemical and physical changes occurring in hydogenated solid and liquid canola and soybean frying fats were examined in two separate frying studies. Samples of the frying fats and french fries were taken at intervals throughout each experiment and were analyzed for a number of chemical and physical parameters. The values for free fatty acids (FFA) and for polar components (PC) were each highly correlated with hours of frying for all types of fats; therefore, equations for predicting levels of PC from FFA values were calculated. All fats contained only moderate levels of degradation products after 5 or 10 days of frying. These levels of degradation products did not appear to affect the sensory qualities of the french fries adversely, and there were only minor differences in sensory quality between fries cooked in liquid soy or canola fats.

Consumer acceptance of canola oils during temperature-accelerated storage

Abstract Ninety-two consumers judged the odour acceptability (yes or no) of regular (12·5% 18:3) and low linolenic acid (2·5% 18:3) canola oils which had been stored at 60°C for 21 and 42 days, respectively. For each storage day an average proportion of acceptance (APA) was calculated. Logistic regression analyses of storage days vs. APA yielded valid relationships for both oils. These equations permitted prediction of the number of days of accelerated storage for APA values from 0·4 to 0·8. The storage time to 0·5 APA, the consumer acceptance threshold, was 12·5 days for regular canola oil and 34·3 days for low linolenic acid canola oil, indicating substantially greater stability for the genetically modified caltivar. The frequency and character of free choice negative odour descriptors which were assigned to both oils at 0·5 APA were similar.

The Flavor Of Fababeans As Affected By Heat And Storage

Abstract Sensory evaluation of fababean flours ( Vicia faba , minor) identified dried pea flavor and bitter aftertaste as the dominant flavor characteristics. In comparing year-old flour from the 1972 crop with freshly milled flour from the 1973 crop, slurries (5% solids) of stored flour exhibited a significantly more intense “dried pea” flavor as judged by a 7-member trained sensory panel. Sensory analysis showed that “dried pea” flavor was stronger in the protein concentrate than in the flour. Relationships between dried pea flavor and free fatty acids were examined in an accelerated storage study. Free fatty acids increased in flour and concentrate although the sensory data did not indicate a corresponding flavor change. Heat treatment of flour and concentrate at 130, 150 and 160°C resulted in a decrease in dried pea flavor although stronger and objectionable novel flavors were introduced for those flours incubated at 150 and 160°C.

Effect of saponin on the surface properties of quinoa proteins

Abstract Quinoa seeds were cleaned, ground, and defatted using hexane. The defatted flour was dispersed and stirred in alkali to extract the proteins, one half of which was desaponized with methanol. The whole seed flour, protein, and desaponized protein fractions were compared for their functional properties. Removal of saponins increased water hydration capacity and lowered the fat binding capacity. The emulsion capacity was also reduced in the desaponized protein although emulsion the stability increased markedly. A slight decrease in buffer capacity was observed which was attributed to the removal of saponins. The foaming capacity and foam stability were affected in the similar manner to that of the emulsifying properties. The removal of saponins also lowered the total nitrogen solubility of quinoa proteins.

Two simplified approaches to the analysis of cereal lipids

Abstract Two simple methods were adapted for analyzing complex cereal lipids. Direct separation of lipids extracted from quinoa seed was performed with the complete separation of components within lipid classes. Different solvent mixtures were used for the sequential development of neutral, galacto lipid and polar lipid components. Utilization of flame ionization detector with TLC permitted quantification of lipid components at levels of total lipids as low as a few micrograms. Optimization of lipid classes separation was achieved with aminopropyl silica with pure fractions analyzed for fatty acids. Lipid separation by solid phase extraction produced a sufficient amount of fractions for quantitative analysis of lipid components and for fatty acid evaluation.

Development of a gas chromatographic system for trapping and analyzing volatiles from canned tuna

Abstract Profiles of canned tuna volatiles were obtained using a simple and effective isolation system and high resolution gas chromatography. A high correlation between the volatile profile, chemical groups of components identified and sensory panel scores was obtained. Two models based on chemical groups of components were developed to predict decomposition and rancid off-odor. Recovery of over 80% of the volatile components from canned tuna was obtained with a coefficient of variation of 3.2%.

A study of gossypol reduction by choline and ethanolamine using a model system

The objective of the present investigation was to assess the effect of choline and ethanolamine on the availability of lysine, employing a cottonseed flour-gossypol model system. The model system was developed so that the time, temperature and level of gossypol used produced a 33–38% decrease in lysine availability. Heating cottonseed flour with gossypol at a ratio of 16:1 at 90 °C for 30 min. reduced the available lysine from 21–22 to 12–14 mmol100 g protein. Different amounts of choline and ethanolamine were added to the model system to compete with lysine for the formyl groups of gossypol. A significant (p < 0.05) increase in available lysine was evident in the presence of 0.8 and 1.6 × 10−1 m choline or ethanolamine. Of the bases examined, ethanolamine was almost twice as effective as choline in restoring the level of available lysine in cottonseed flour.

Isolation and partial purification of phytase from Vicia faba minor

Abstract Phytase was partially purified from small fababeans by ammonium sulphate fractionation and Sephadex gel filtration. Phytase activity coincided with phosphatase activity, suggesting it may be part of the general group of phosphatases. Kinetic studies showed that the properties of fababean phytase were similar in general to those of phytases from other sources. Fababean phytase was inhibited by the presence of substrate concentrations greater than 1·5 mM.