Fluorescence spectra of some common vegetable oils, including olive oil, olive residue oil, refined olive oil, corn oil, soybean oil, sunflower oil, and cotton oil, were examined in their natural state, with a wavelength of 360 nm used as excitation radiation. All oils studied, except extra virgin olive oil, exhibited a strong fluorescence band at 430–450 nm. Extra virgin olive oil gave a different by interesting fluorescence spectrum, composed of 3 bands: one low intensity doublet at 440 and 455 nm, one strong at 525 nm, and one of medium intensity at 681 nm. The band at 681 nm was identified as the chlorophyll band. The band at 525 nm was at least partly derived from vitamin E. The low intensity doublet at 440 and 455 nm correlated with the absorption intensity at 232 and 270 nm of olive oil. The measurements of these fluorescence spectra were quick (about 5 min) and easy and could possibly be used for authentification of virgin olive oil.
A new calculation method for the determination of iodine value (IV) from measurements of fatty acid methyl esters is proposed. The method is based on the quantitative determination of fatty acid methyl esters of vegetable oils by capillary gas chromatography. IV is a measure of the number of double bonds in the unsaturated fatty acids in one gram of oil. The analytical methodology of its evaluation includes the use of rather health dangerous reagents, and for that reason is mostly avoided by laboratory analysts. A calculation procedure to determine the IV of oils from their fatty acid methyl ester composition is in use based on the American Oil Chemists’ Society (AOCS) method Cd 1c‐85. A new calculation procedure for IV, based also on the evaluation of the fatty acid methyl esters of oils, was developed. The application of the proposed calculation methodology was checked with olive oil, corn oil, soybean oil, cottonseed oil, and sunflower seed oil. The proposed calculation gave results in better agreement with the Wijs method than with the relevant AOCS method.
Hard-to-cook and easy-to-cook bean and lentil seeds were boiled in water containing calcium ions at concentrations of 0, 40, 80, 120 and 160 mg L −1 and their texture and concentration of phytate and various peptic compounds were measured. In order to minimise matrix effects, hard-to-cook seeds were prepared from easy-to-cook seeds by soaking them at 50• C. It was found that, as calcium ion concentration increased, phytate concentration decreased and seed hardness increased. Also, during soaking and cooking, phytate and peptic compounds were leached into the water. Losses were larger for hard-to-cook seeds than for easy-to-cook seeds. These results are consistent with the proposed theory that the formation of hard-to-cook legume seeds involves an interaction among divalent cations, phytate and peptic compounds, which is based on the phytase-phytate-pectin hypothesis.
2007 Society of Chemical IndustryKeywords: phytase-phytate-pectin hypothesis; hard-to-cook; legumes
INTRODUCTIONGrain legumes, especially common bean (Phaseolus vulgaris L.) and lentil (Lens culinaris Medicus), are a staple food for people in many parts of the world. A shortcoming of these legumes is the hard shell and associated hard-to-cook phenomenon that develop after storage under conditions of high temperature and relative humidity. This hardness and the concomitant need for long cooking times lead to reduced palatability, increased fuel consumption and reduced protein digestibility.1,2 Owing to the importance of legumes in the human diet, the hardto-cook phenomenon has been extensively studied.
Olives from three different locations (Olea europaea cv. Koroneiki), uninfected or infected by the insect Dacus oleae, were collected and stored at 15°2C for 21 days. Samples were taken at 0, 3, 7, 10, 12, 14, 17 and 21 days following collection. Moisture and oil content of olive fruits and the quality parameters of the extracted virgin olive oil were evaluated. Analytical parameters determined were titratable acidity, peroxide value and the specific extinction coefficients at 232 nm (K232 and 270 nm (K270). Regression equations and best fitting curves between examined parameters and time were evaluated. Olive oil from fly infected olives had higher initial values and a higher rate of increase of the parameters measured. The only parameter affecting oil quality was K270. Maximum storage time within legal limit for K270 was 16 days for fly uninfected and 10 days for fly infected olives.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.