Effect of carbohydrate degradation upon browning and corrosion in canned applesauce

Two statistical methods are described. These were used for the derivation of regression line, coefficient of correlation, and experimental error, and for the use of control charts in laboratory experiments, as a simple technique for the derivation of accuracy and precision. The two methods mentioned above were modified for application to this work.

A micro method for quantitative, simultaneous determination of fructose, glucose, and sucrose in foods was developed. A reflectance method was modified to determine browning in applesauce. The modified method can be applied to any homogeneous, flowing food.

The canning of fruit and vegetable food products in metallic containers leads to the dissolution of metals within the food products. Formation of complexes takes place between carbohydrates, proteins, fats, their degradation products, and the metal cations. Various types of chelates are eventually formed under these conditions. The presence of trace metals in food products, whether they originate from processing water or from corrosion reactions, influence the dissociation of the sugars and ultimately the color and the keeping quality of the canned products. A tentative explanation of the mode and rate of sugar degradation in the presence of tin ions in canned applesauce was developed. Various types of chelates likely to be formed between sugar intermediates and tin cations are suggested.

The presence of certain additives in applesauce also influenced the rate and mode of the degradation process. The following observations were made:

1. Hydroxymethyl furfural increases corrosivity and browning in canned applesauce.
2. Betaine appears to be an efficient corrosion inhibitor, reducing corrosion without excessively increasing overall browning.
3. Lecithin appears to be a better corrosion inhibitor than betaine. However, this advantage is negated by its greater tendency to produce browning.
4. Glutamic acid is a satisfactory corrosion inhibitor. It is, however, believed to be less stable than lecithin and betaine, especially at 100°F. Therefore, to achieve the desired result, higher levels would have to be used.
5. Cystine can be considered to be an efficient chromophoric inhibitor. It is a satisfactory corrosion inhibitor for temperatures not exceeding 75°F.

It is recommended that future research take into account the importance of trace metals on the quality and storage life of fruit and vegetable products. A better understanding of the degradation process could be achieved by a study of the nature of the chelates occurring between dissolved metals and various degradation intermediates in canned fruit and vegetables products stored under various conditions of time and temperature.

The commercial sucrose used in preparing processed food products should be examined for trace impurities. The trace constituents of sucrose can have an influence both on can corrosion and browning formation. Care should be taken in controlling the presence of metal cations in the water used for processing.