HPLC Analysis of Phytic Acid in Selected Foods and Biological Samples

Analytical Methods for Determination of Phytic Acid and Other Inositol Phosphates: A Review

From the early precipitation-based techniques, introduced more than a century ago, to the latest development of enzymatic bio- and nano-sensor applications, the analysis of phytic acid and/or other inositol phosphates has never been a straightforward analytical task. Due to the biomedical importance, such as antinutritional, antioxidant and anticancer effects, several types of methodologies were investigated over the years to develop a reliable determination of these intriguing analytes in many types of biological samples; from various foodstuffs to living cell organisms. The main aim of the present work was to critically overview the development of the most relevant analytical principles, separation and detection methods that have been applied in order to overcome the difficulties with specific chemical properties of inositol phosphates, their interferences, absence of characteristic signal (e.g., absorbance), and strong binding interactions with (multivalent) metals and other biological molecules present in the sample matrix. A systematical and chronological review of the applied methodology and the detection system is given, ranging from the very beginnings of the classical gravimetric and titrimetric analysis, through the potentiometric titrations, chromatographic and electrophoretic separation techniques, to the use of spectroscopic methods and of the recently reported fluorescence and voltammetric bio- and nano-sensors.

Physicochemical, functional, and nutritional characteristics of stabilized rice bran form tarom cultivar

Extrusion is a multistep thermal process which has been utilized in a wide spectrum of food preparations. The effect of extrusion processing on the physicochemical, nutritional, and functional properties of Tarom cultivar rice bran was studied. However, the color of rice bran was improved by extrusion processing, but the protein content was reduced in the stabilized rice bran, which can be related to the denaturation of protein. Extrusion had also a reduction significant effect on the phytic acid as well as vitamin E in rice bran. However, the content of niacin, riboflavin, pantothenic acid, and folic acid remained unchanged, but the dietary fiber was enhanced which has beneficial health effect on human consumption. In comparison with unstabilized rice bran, water holding capacity was enhanced, but the oil absorption capacity was reduced. Foaming capacity and foaming stability of extruded rice bran was more than that of untreated rice bran, although they were less than that of rice bran protein concentrate/isolate. In general, the extrusion process improves some functional and nutritional properties of rice bran which are valuable to industrial applications and have potential as ingredient in food to improve consumer health.

Rapid measurement of phytate in raw soymilk by mid-infrared spectroscopy

The phytate content in soymilk is known to affect tofu curdling. A rapid measurement of phytate from a water extract of soybean (raw soymilk) in an early stage of tofu processing was investigated using mid-infrared spectroscopy (IR) with an ATR accessory. IR absorption of phytate was observed from 1200 cm-1 to 900 cm-1, and saccharide and protein in the extract also had IR absorption in the same region. In order to separate phytate from other components, the phytate was precipitated completely by the addition of calcium under alkaline condition (pH 11.5). The precipitate was dissolved in citrate buffer (pH 6.0) and then used for IR measurement. The absorbance at 1070 cm-1 correlated well with the phytate content of the soymilk. The measurement of phytate in raw soymilk can be done rapidly by FT-IR measurement with an ATR accessory and gives reproducible values, which can be used for the measurement of phytate content in various soybeans for tofu making.

The phytate and mineral content of some cereals, cereal products, legumes, legume products, snack bars, and nuts available in New Zealand

Analyses for phytate by an indirect precipitation method and for the minerals calcium (Ca), zinc (Zn), iron (Fe), copper (Cu), and manganese (Mn) by atomic absorption spectrophotometry were carried out on 100 foods available in New Zealand. Foods with 1% phytate (dry weight basis) included untoasted muesli, rolled oats, wheat germ, wheat bran, soybean, and some soy products. Most breads contained between 0.35 and 0.60% phytate; legumes on average had 0.62% phytate, as did snack bars. There was a wide variation in Ca and Zn contents: There was a tenfold variation in Ca content among the legume products, whereas there was a seventyfold variation in Zn content among the cereals. The phytate: Zn molar ratio, which is presumed to indicate the biovailability of Zn, was above 20∶1 for two-thirds of the cereals and almost all of the snack bars; it was above 15∶1 for one-third of the breads, almost all of the legumes, and half of the legume products. These high phytate: Zn molar ratios, as well as some Ca: phytate molar ratios above 6∶1, indicate that there might be a reduced biovailability of Zn in many of the foods analyzed in this study.