Effect of pre‐fry drying of oil uptake and distribution in potato crisp manufacture

Abstract

Microwave, hot air (40 and 105OC) and freeze drying were used to remove varying amounts of moisture from 1.3 mm thick potato slices. The partially dried slices were then fried in oil at 165°C either for a constant 2 minor a variable frying time based on the amount of pre-drying. The microwave and hot air treatments resulted in a reduction in the final oil content, which was related to the degree of pre-fry drying. Freeze drying resulted in an increase in the oil content, again related to the initial moisture reduction. Oil distribution at the microscopic and macroscopic level was determined and found to be related to the initial moisture distribution in the slice. It is suggested that pre-fry drying may be a more successful point of influence than post-fry treatment in the manufacture of a 'lower fat crisp'.

Relationship between Oil Uptake and Moisture Loss during Deep Fat Frying of Deboned Chicken Breast Meat

“…In the second phase (>45 s), moisture loss increases almost linearly (Figure 1(b)), as also reported for potato strips by Mittelman et al [8], with a slight convexity (>600 s) representing the onset of mass-transfer limitations. The effect of frying oil temperature (FOT) becomes more evident (separation of curves) after about 175 s, moisture loss being significantly affected by FOT.…”

“…In the case of moisture loss, the latter increment has nevertheless, a noticeable effect on the slope, whereas in the case of oil uptake, the change in slope is negligible. Kassama and Ngadi [10], Gambleand Rice [8] observed a similar decreasing effect of higher frying oil temperatures on oil uptake in chicken breast meat and potato slices, respectively.…”

“…In contrast, Gambleand Rice [8] reported that oil uptake was directly proportional to moisture content over the full range of moisture content (1% to 80%) in thick slice potatoes (1.5 mm). Although, our results may differ due to the inherent differences of the pore structure and the pore size distribution of the products, however, the limiting factor to the transport mobility of moisture and oil observed may not have been detectable in much thinner slabs.…”

“…It has been shown that fat absorption by thin potato slices is directly related to the amount of moisture lost; hence moisture loss is directly proportional to the square root of frying time, and the frying oil temperature has indirect effect on oil absorption [7]- [9]. These relationships have been studied for various foods [8]- [14]; however, there is some disagreement as to the mechanisms of fat absorption. Moreover, fundamental differences in composition and structure of various food materials make it difficult to generalize results, even though foods in general are considered to be hygroscopic porous media [1].…”

Effect of hydrocolloids incorporation in casing of samosa on reduction of oil uptake

“…Crust formation and browning also take place giving the product an attractive golden appearance and crispy mouthfeel (Annapure et al 1998). The amount of oil uptake is directly proportional to the amount of moisture lost (Gamble and Rice 1987). The oil uptake and its distribution in the fried product is mainly near the surface i.e.…”