A Novel Method for the Determination of Synthetic Colors in Ice Cream Samples

A simple method has been developed for the extraction, separation, and determination of synthetic colors in ice cream samples. The process involves the breakdown of emulsion by neutral detergents (Triton X-100 and Tween 20) followed by extraction with petroleum ether for removal of fat. The aqueous colored solution obtained is treated with 5% acetic acid, and the uptake of color is carried out by a wool-dyeing technique. The color is eluted from the wool with 5% ammonia solution, the solution is evaporated to dryness, and the residue is dissolved in 60% ethanol for paper chromatography using trisodium citrate–ammonia–water (2 + 5 + 95, w/v/v) as the mobile phase. The colored spots from the paper chromatogram are cut and eluted with 60% ethanol, and the absorbance is measured at the respective λ maximum corresponding to the Rf value of the appropriate standard. The recoveries of 6 colors, including sunset yellow FCF (SSYFCF), tartrazine, carmoisine, ponceau 4R, brilliant blue FCF (BBFCF), and fast green FCF from spiked samples with either detergent were found to be >90%. However, recoveries of erythrosine were 21 and 65% with Triton X-100 and Tween 20, respectively. Indigo carmine could not be recovered at all because of its fugitive property in 5% ammonia solution, which is used to strip the color from the wool. The sensitivity of the method with the use of Tween 20 is 1 ppm (1 μg/g) for the colors in spiked ice cream samples. With this method, we analyzed samples of 20 branded colored ice cream. The results showed the presence of tartrazine (8.4–43.3 ppm), SSYFCF (23.5–117.6 ppm), carmoisine (traces–53.2 ppm), erythrosine (3.5 ppm), and BBFCF (4.1 ppm) in the ice cream samples. Apart from 2 samples of tuttifruity, all of the ice cream samples showed the presence of permitted synthetic colors below the permissible level of 100 ppm established by the Prevention of Food Adulteration Act of India.

Elution of Artificial Colors from Cardboard and Wrapping Paper Used for Food Packages

In Japan artificial colors and pigments can be used for food packages if they are processed so that the artificial color or pigment will not be eluted to contaminate food. Ten samples of cardboard and five samples of wrapping paper were subjected to the elution test. One hundred cm2 of cardboard or paper was immersed in water at 40 C and held for 30 min. Artificial color was eluted from all samples of whole cardboard and, when it was divided into three parts (surface, inner part and reverse side) to do the elution test separately, artificial color was eluted from all parts except with one sample when color was eluted only from inner part. By comparing Rf values on a paper chromatogram as well as its maximal absorbance with color standards, the eluted color was identified to be croceine orange. Congo red and croceine orange were eluted each from one sample of wrapping paper.

Identification of guanosine diphosphate derivatives of d-xylose, d-glucose and d-galactose in mature strawberry leaves

The nucleotides from a trichloroacetic acid extract of mature strawberry leaves were separated into ten main fractions by chromatography on a Dowex 1 (formate form) column with ammonium formate as the eluting agent. One of these fractions, which was suspected to contain not only ADP but also GDP-sugars, was separated into a number of subfractions by further chromatography on a Dowex 1 (formate form) column with the formic acid system as the eluting agent. One of these subfractions was identified from its ultraviolet spectra, from its position on the two ion-exchange columns and by thin-layer chromatography as a GDP-sugar. Mild acid hydrolysis gave GDP and a mixture of sugars. The sugars, after a preliminary separation on a paper chromatogram, were identified by an isotope-dilution method. The sugars were condensed with sodium [14C]cyanide, the [14C]nitriles were hydrolysed and one of the epimeric acids was isolated, either as lactone or amide, by co-crystallization with a non-radioactive carrier. This method distinguishes between enantiomorphic sugars. d-Mannose, d-xylose, d-glucose and d-galactose were present in the proportions 40:10:1:1 respectively. The total amount of the GDP-sugars was approx. 0·1μmole/100g. of fresh leaves.

Fluorometric estimation of antigens (antibodies)

A method for the titration of antigens based on separation by filtration through millipore filters of the complex of antigen with fluorescein isothiocyanate-labeled antibodies from free labeled antibodies and nonspecific γ-globulins is described. The fluorescence of the antigen-antibody complex is measured directly on the millipore filters using the Turner fluorometer equipped with a paper chromatogram door. The limit of sensitivity of the method is about 0.05 μg of antigen protein. Quenching of fluorescence by nonlabeled antibodies can be used for the titration of antisera. An example of the application of the method for titration of rabies virus antigen is also presented.

The sulpholipids of plants I. The distribution of sulpholipids and phospholipids among the major plant classes

It is shown that sulpholipid is the predominant acetone-insoluble lipid of grass, sphagnum moss, Selaginella, and of some blue-green, green and brown algae.This sulpholipid is separable into three entities by paper chromatography.Phospholipid predominates over sulpholipid in red algae, fungi and the fluffy pericarp of the broad bean.The sulpholipid in these plant tissues gives a single spot on paper chromatogramA relationship between sulpholipids and photosynthesis is suggested.