Food Tannins Measurement, Determination of Food Tannins by Ultraviolet Spectrophotometry

Abstract

ated meat samples. At lower temperatures, the time required to ebulliate all the mercaptan was too long for convenient routine assay. At higher temperatures, the possibility of inaccurate high values as the result of protein degradation appeared likely.A series of experiments was run to determine the effect of short storage periods on the volatile methyl mercaptan content of irradiated beef. No significant difference in the amount of methyl mercaptan was noticed within 36 hours after irradiation, if the irradiated samples were stored in the frozen s:ate at -18°C.Thus, as long as the irradiated samples were kept frozen, methyl mercaptan could be quantitatively determined within 36 hours after irradiation.On the basis of methyl mercaptan determinations on a large number of irradiated-meat samples, the methyl mer-captan content of beef increases directly with gamma-irradiation dosage (Table III). In addition to this dosage effect, there is a difference in the amount of methyl mercaptan formed in different samples of beef during irradiation. Literature Cited(1) Almv, L. H., J. Am. Chem. Soc. 47, 1381-90 (1925).

Phenolics in cereals, fruits and vegetables: Occurrence, extraction and analysis

“…On the other hand, complexation of the phenolic with Al(III) is the principle of spectrophotometric assays used for quantification of total caffeic acid and total flavonoids [293][294][295]. Furthermore, simple phenolics have absorption maxima between 220 and 280 nm [296,297], but their absorption is affected by the nature of solvent employed and the pH of the solution. Moreover, the possibility of interference by UV-absorbing substances such as proteins, nucleic acids and amino acids should be considered.…”

Extraction, separation, and detection methods for phenolic acids and flavonoids

“…Simple phenolics have absorption maxima between 220 and 320 nm but their absorption is affected by the nature of the solvent and the pH of the solution [213]. On top of this, the possibility of interference by UV-absorbing substances such as proteins, nucleic acids, and amino acids should also be considered.…”

Analytical methodologies for quantification of ferulic acid and its oligomers

“…The measurement of sample absorbance at a characteristic wavelength is another simple way of quantifying phenolic acids 47–50. This technique was thus naturally applied to ferulic acid content measurements by reading the absorbance at 320 nm of chloroform extracts of rye and wheat grains or at 340 nm for acid‐hydrolysed extracts of barley 51, 52.…”