[Reduction of the transfer of surface active agent residues in food]. / Minderung des Tensidübergangs von Werkstoffoberflächen auf Lebensmittel.

Surfactants used for cleaning and disinfection in food production and food processing can form residue on treated materials. Upon sequential contact of these materials with foods these foods may become contaminated. Different materials (steel, acrylonitrile rubber, polypropylene, polyamide, methyl methacrylate) were treated with aqueous solutions of dodecyl-trimethyl-ammoniumchloride, a bactericidal quaternary ammonium compound, and stearyl alcohol oxethylate, a nonionic surfactant. The adhering amounts of surfactants were measured by a radio tracer technique. It was analysed, how much of the adhering surfactants could be removed with water depending on rinsing time, water temperature, flow velocity, and number of rinsing cycles. It has furthermore been determined to what extent adhering surfactants are rinsed off by milk and juice.

[Contributions to mechanical dishwashing. III. Dynamics of removal of protein residue from glass surfaces (author's transl)]. / Beiträge zum maschinellen Geschirrspülen. 3. Mitteilung: Zur Dynamik des Ablösens von Proteinrückständen von Glasoberflächen.

Using tracer technique the removal of protein soil--dried casein resp. skin milk--from glass plates by mechanical dishwashing was investigated. Prerinsing for 2 min with cold tap water removes 91.25 percent of the quantity of casein originally present. When this prerinse is followed by 20 min main wash, the residual casein can be removed if at least 30g of detergent has been added to 131 water. Optimum inter-relation-ships of quantity of detergent added with time and temperature of the washing and rinse cycles are given. Dry protein residues from skim milk are more easily removed than casein residues, probably because the salts and lactose dried together with the proteins facilitate the cleaning.

[Photometric micro-determination of the residues of disinfectant quaternary ammonium compounds in milk. 3. Improvement and adaption for milk products (author's transl)]. / Photometrische Mikrobestimmung der Reste keimtötender QAV in Milch 3. Methodische Verbesserung und Erweiterung.

The photometric method for the quantitative micro-determination of the residues of quaternary ammonium compounds (QAC) in milk was improved. The casein has proved as an essential interfering substance and it was largely eliminated. Furthermore the bond of QAC on casein in discussed. The minimum level für determination for QAC in milk was reduced to 0.2 ppm. By modifying the photometric method for some milk-products as cream, joghurt, and quarge QAC can be determined at minimal concentrations of 1 ppm.

[Thoughts about the qualification of assessors for sensory testing (authors transl)]. / Gedanken zum Qualifikationsmassstab (BQ) für Prüfpersonen anhand des Tetradentestes nach Renner und Römer

On the occasion of a storage test in order to evaluate the tightness of milk packing materials to permeating flavours by sensory analysis the statistical method for judging the concerned assessors recommended by Römer and Renner was applied. We gained the experience, that this method allows no statement about the assessor's sensory ability at all, but merely fixes his order of precedence in a panel as to his ability to realize sensory differences in the scope of one special problem. The mentioned statistical procedure cannot substitute a selection of assessors aimed at the subject of the following sensory analysis.

[Investigations on the influence of insecticides on autoxidation processes. X. Formation of peroxides from octadecenic acid methylester in the presence of water and chlorinated hydrocarbon insecticides (author's transl)]. / Untersuchungen und Betrachtungen zum Insecticideinfluss auf Autoxydationsprozesse. X. Peroxidbildung aus Octadecensäuremethylester in Gegenwart von Wasser und insecticiden Chlorkohlenwasserstoffen

According to the range DDT less than DDE less than heptachlor less than heptachlorepoxide, chlorinated hydrocarbon insecticides promote the formation of peroxides from cis- and trans-9-octadecenic acid methylesters within the lipid and the water phase of the investigated model system. Compared with DDT and heptachlor the metabolites DDE and heptachlorepoxide proof as more efficient prooxidants; this may be explained by their higher reactivity. According with these observations the amount of insecticides, especially of heptachlor and heptachlorepoxide, that can be extracted from the model system with petroleumether after 72 hrs of autoxidation is markedly diminished. From that it is concluded, that in the investigated lipid-water-system the insecticides not only have a catalytic effect, but also are in part immediately involved in the formation of peroxides from 9-octadecenic acid methyl ester.

[Investigations on the influence of insecticides on autoxidation processes. XI. Formation of secondary metabolites from octadecenic acid methyl ester in the presence of water and chlorinated hydrocarbon insecticides (author's transl)]. / Untersuchungen und Betrachtungen zum Insecticideinfluss auf Autoxydationsprozesse. XI. Bildung sekundärer Umwandlungsprodukte aus Octadecensäuremethylester in wässrigem Milieu in Gegenwart insecticider Chlorkohlenwasserstoffe

For determining the influence of chlorinated hydrocarbon insecticides on the formation of secondary metabolites from peroxidized 9-octadecenic acid methylester by autoxidation within 72 hrs, substances reacting with phosphomolybdanic acid have been separated by TLC. Furthermore the increase of metabolites containing carbonyl groups and the variation of the ratio of polar to unpolar OH-groups in the metabolites have been determined by IR-spectrophotometry. All results proved, that the trans-9-octedecenic acid ester is autoxidized more rapidly than the cis-ester. Moreover the insecticides principally favour the formation of secondary metabolites from the lipidperoxide. This effect increases in the range DDT, DDE, heptachlor, heptachlorepoxide. If the increase of metabolites with carbonyl groups is chosen as a measure for the prooxidative effect, the effect appears equally high for the cis- and the trans-ester. But the hydroxyl index is changed depending on the kind of the insecticide added and the steric configuration of the lipid.