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In this study, we developed a novel, simple, rapid, and low-cost colloidal gold-based immunochromatography method, with filter paper replacing nitrocellulose membrane as the substrate. To obtain adequately immobilized protein, chitosan was used to functionalize the filter paper. After conditions and parameters were optimized, the novel immunochromatography method was applied for detection of sulfonamide residues in milk. Quantitative detection was accomplished using a smartphone and Photoshop software (Adobe Inc., San Jose, CA), allowing us to screen 13 sulfonamides with a limit of detection ranging from 0.42 to 8.64 μg/L and recovery ranging from 88.2 to 116.9% in milk. The proposed novel method performed similarly to the conventional method that uses a nitrocellulose membrane as the transport medium, and it had lower cost and better usability because of the inexpensive and easily available filter paper.

Eleven papers were compared for absorption of whey and for digestibility in vitro. Papers were squared, ground, and soaked in whey for 1,5, and 15 min and for 1, 6, 24, 48, and 72 h. Digestibility in vitro was determined on minimum and maximum whey absorption of each squared and ground paper sample. Whey absorption by squared papers increased with time. Ground samples absorbed more whey than squared ones and maximum quantities were absorbed within 1 to 5 min. Mean percent absorptions for ground telephone book covers, glossy magazines, computer cards, computer printout sheets, daily newsprint, telephone directory yellow pages, cardboard box, feedsacks, brown bags, telephone directory white pages, and coasters were: 31.0, 35.2, 35.4, 36.5, 43.9, 47.9, 51.0, 51.4, 51.7, 55.6, and 67.4. For seven papers, addition of whey increased digestibility. Four papers were either unchanged or decreased in digestibility. This depression of digestibility may have resulted from the high fat content of whey used. Based on in vitro digestibilities, we conclude that it is possible to recycle selected paper/whey combinations through ruminants.

A new reduction method using resazurin-impregnated filter paper was applied for determining the sanitary quality of raw milk. Experimental results of standard agar plate and resazurin test paper methods showed a high correlation between the plate count and the resazurin reduction time. By measuring the velocity constant of the reaction, color change from resazurin to resorufin on the filter paper indicated it to be a unimolecular reaction. It was concluded that the resazurin test paper method has the advantage of accuracy and simplicity for a field test.

Summary Alpha-, beta-, and gamma-components of casein were separated by paper electrophoresis, and the dyed proteins in paper were estimated by direct photometry. Correction factors were determined because the components did not bind dye in proportion to their concentration. Protein concentrations corrected for differences in dye-binding capacities agreed with results of protein-nitrogen analyses, and casein composition was alpha-, 60%; beta-, 32%, and gamma-, 9%.

Summary Sugars in ice cream were separated by descending: paper chromatography, using an irrigation solvent system consisting of n -butanol :ethanol :water (2:1:1 v/v). Paper strips containing the resolved sugars were eluted with water. Quantitative determinations were performed photometrically on aliquots of eluates reacted with anthrone reagent. No preliminary treatment of the ice cream was necessary except dilution with water. The following sugars could be resolved on a single chromatographic strip: fructose, glucose, galactose, sucrose, maltose, lactose, and higher sugars. Four sugars, glucose, sucrose, maltose, and lactose, formed distinct spots when an ice cream containing corn syrup was analyzed. Recoveries ranging from 93 to 104% and averaging close to 100% indicate a fair degree of reliability of the technique.

Summary Paper chromatographic methods are presented for the resolution and identification of maltol and hydroxymethylfurfural. By using such methods these compounds were detected in highly heated milk (120° C., 2 hours) and in samples of evaporated milk produced and distributed under commercial conditions. Neither of these compounds could be detected in milk receiving limited (65.6° C., 20 minutes) heat treatment.

Summary To study the electrophoretic properties of milk proteins under conditions as nearly similar as possible to those found in milk, a paper strip electrophoresis apparatus was designed which required small volumes of electrolyte and in which electro-osmosis could be substantially reduced. Using this apparatus, it was shown that β -lactoglobulin could be isolated from milk, crystallized, and returned to its native environment without grossly affecting its initial charge density.

Summary A study has been made of the paper electrophoresis of casein and casein fractions in Veronal buffers containing urea levels from 0 to 7.0 M . A method using the Sharples supercentrifuge was developed that permits the isolation of whole κ -casein from α-casein without the need for an ultracentrifuge. It was found that whole κ -casein migrates in the α, or fastest-moving peak, when the urea level is 0–2.5 M , but migrates in the β , or second-fastest peak, when the urea level is about 6.0–7.0 M . Veronal buffers containing urea levels of about 2.5 M or greater (pH ∼ 8.9, Γ/2 0.050) permit the resolution of casein into at least six components; four of these components migrate slower than β -casein. κ -Casein could not be completely resolved from the other components of whole casein, although at 4.8 M urea the κ -casein formed a peak between α s - and β -casein. Whole κ -casein became increasingly heterogeneous as the urea level of the buffer was increased. Whole casein contained approximately 39% α s -casein, 11% κ -casein, 43% β -casein, and 7% minor components. The use of urea in electrophoresis buffers for casein appears promising as a high order of resolution is attained. The effect of urea level on the migration of κ -casein appears important in quantitative studies on the relative abundance of casein fractions.

Summary The analyses of human, cow, rat, and sow milk after the removal of proteins and salts have disclosed some marked differences in their respective chromatographic patterns. All, of course, contained lactose. In addition, human milk contained 11 other unidentified spots as compared to eight for sow's milk, six for rat's milk, and ten for cow's milk. Glucose was found in human milk and galactose and glucose in cow's and sow's milk, whereas rat's milk contained neither galactose nor glucose.

Summary A quantitative method for lactose determination in milk by chromatographic analysis is described. Direct application of milk to the strip and subsequent determination of lactose on the chromatostrip after partitioning are desirable features of the procedure. The reproducibility of the method was determined for lactose in pure solution and in milk. At a mean value of 4.516% lactose, anhydrous, in milk the optimum standard deviation was 0.16%. The recovery from milk of added lactose, anhydrous, varied between 92 and 97% and averaged 95%.

Ground waste paper absorbed approximately three times its weight of blackstrap molasses. Upon drying, a stable and friable product resulted. It appeared to be palatable when included in the diet of lactating cows. Yearling heifers gained 0.8 kg daily on a ration which included 1.1 kg of paper and 1.7 kg molasses.

Filtration of the residue from the in vitro rumen true digestibility determination was attempted on filter paper. In the first experiment, comparisons were between in vitro true and apparent digestibility and between filter paper and sinter glass crucibles. There were significant (P A second experiment, consisting of a series of in vitro true digestibilities with concurrent blank fermentations, was conducted. When the estimates using filter paper were corrected for the blank fermentations, they were not significantly different from those with crucibles. The results suggest that filter paper can be substituted for crucibles in the estimation of in vitro rumen true digestibility provided a blank fermentation is conducted concurrently.

In vitro dry matter disappearances were determined for 11 paper sources and three complete rations containing 0, 10, and 20% newsprint. Inoculum was from an alfalfa hay-fed steer. Alfalfa hay, brome hay, and Solka Floc were reference substrates. Brown wrapping paper and brown cardboard had the highest dry matter disappearances of 90.8 and 77.8%; whereas four glossy or slick magazine papers had significantly lower values of 46.1, 45.1, 41.3, and 41.0%. Newsprint with black ink, without ink, and with colored inks had dry matter disappearances of 33.2, 32.6, and 26.5%, which were significantly lower than those of the glossy magazine papers. Lowest dry matter disappearances of 24.0 and 20.1% were from two magazine papers. The complete rations had 77.9, 80.1, and 81.8% dry matter disappearances for the 0, 10 and 20% paper rations. These data indicate substantial differences in digestibilities of various paper sources.