The effect of calcium fertilization on the processing properties and storability of frozen French fries was investigated using three different varieties of processing-type potatoes, namely Toyoshiro (TS), Kitahime (KH) and Snowden. We attempted to understand the possible mechanisms contributing to quality differences in the French fries, by comparing tuber, starch and cell wall material properties. Calcium fertilization significantly increased the calcium contents of cell wall materials of all varieties, while a significant increase in chelating-agent soluble pectin content was observed in TS. The oil content of French fries was not significantly affected by calcium fertilization. On the other hand, two-way ANOVA indicated a significant effect of calcium fertilization on the hardness of the center and bud-end of French fries after 24 weeks of frozen storage. Results of this study suggest that calcium fertilization may be an effective method to improve the processing properties and storability of French fries.Keywords: French fries, calcium fertilization, processing properties, frozen storability, texture, oil uptake
IntroductionFrench fries are a popular food world-wide because of their pleasant taste, which is created by the combination of a crispy crust, soft inside and typical fried potato flavor (Van Loon et al. 2005). Frozen French fries, a semi-processed food product that is a common form of French fries, are produced from raw potato generally by washing, peeling, cutting, blanching, drying, parfrying and freezing (Gould 1999). The frozen French fries are finalfried by consumers, e.g., households and restaurants, prior to serving. During frozen storage of French fries, however, the growth of ice crystals, known as an ice recrystallization, is promoted by prolonged periods of frozen storage (Sutton et al. 1996; Hagiwara et al. 2002; Pronk et al. 2005), and the presence of large ice crystals within the tuber tissue can result in physical damage, drip loss and a consequent reduction in product quality (Sun and Li
2003).Texture is a major factor determining consumers' acceptance of French fries, and depends on both the characteristics of the raw material and the processing history (Du Pont et al. 1992). In addition, oil content is another important quality characteristic of French fries that contributes to consumer acceptability (Romani et al. 2008), notable because of the demand to reduce the oil content of fried foods in response to health concerns (Moreira and Barrufet 1998). According to various studies, the tuber, starch and pectin D. MurayaMa et al. 452 properties of potato contribute to the texture as well as the oil uptake of French fries (Kirkpatrick 1956; Johnston et al. 1970; Sayre et al. 1975; Aguilar et al. 1997; Khalil 1999; Tajner
Materials and MethodsPotato varieties Three processing varieties of potatoes (Solanum tuberosum L.) were used in the present study, namely Toyoshiro (TS), Kitahime (KH) and Snowden (SD). TS is an early variety, while KH and SD are late varieties.Potato pro...
