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A new, energy efficient production process for French fries was developed and evaluated. Superheated steam (SHS) was used for evaporation of water instead of pre-drying with air and par-frying with oil. The product was frozen by vacuum cooling. Unfortunately, with this process it was not possible to reach the quality of conventional French fries. Sensory analysis indicated that the main quality defect was a tough crust with a fatty appearance. Confocal Scanning Laser Microscopy showed that this was caused by skin formation on the surface during both SHS drying and vacuum cooling. A frying step was necessary to obtain a porous crust. A satisfactory product quality was feasible after drying with SHS instead of air. Due to the concessions made for the product quality, the final energy reduction was limited. Nevertheless, this study has gained more insight into how processing affects potato tissue on micro-scale and it has shown that a porous structure is essential for good quality French fries.

Polythene terephthalate (PET) is frequently used as a packaging material for mineral water and other non-alcoholic beverages. PET contains detectable amounts of acetaldehyde, which is able to migrate to its packed product. An automated headspace gas chromatographic method for the determination of acetaldehyde has been developed and was used for the quantification of acetaldehyde in aqueous food products and their PET packages. A cold trap, mounted in the GC oven, between the auto sampler and analytical column was introduced as a new application. The detection limit of acetaldehyde was found to be 3 ng/ml with a standard deviation of 3%. The contents of acetaldehyde found in carbonated mineral water and lemonade ranged between 11 ng/ml and 7447 ng/ml, while the contents of acetaldehyde in the PET packages ranged from 1.1 microgram/g to 3.8 micrograms/g.

Uronides and saccharides were determined in the ethanol-insoluble residue of some fruits and vegetables, and in the pectin, hemicellulose and cellulose fractions of that residue. For molecular absorption spectrometry of uronides, enzymic, acidic and alkaline extraction were compared. The sugar composition was determined by gas chromatography after enzymic hydrolysis and trifluoroacetic acid (concn. 2 mol/1) or Saeman hydrolysis [sulphuric acid (concn. of H+ 0.8 mol/1 or 2 mol/1)]. Uronide contents found by molecular absorption with m-hydroxydiphenyl and copper binding were of the same order of magnitude. Saccharide composition of samples and fractions varied widely.