Fry Shortening Evaluation
Cake and yeast-raised donut deep frying studies comparing partially hydrogenated soybean oil (approximately 31% trans fat), a palm/soy blend, conventional soybean shortening and high oleic soybean shortening prove that donut fry shortening made with high oleic soybean shortening performs similarly to traditional shortenings made with partially hydrogenated oils.
Donut Fry Shortening Evaluation
In the study, high oleic soybean shortening produced donuts similar to those made with partially hydrogenated soybean oil; the analysis measured texture, spread, height, oil weeping and more. High oleic soybean oil also performed favorably in a sensory panel and fry-life evaluation.
Donut Performance
In the cake donut study, high oleic soybean oil shortening produced donuts with star-shaped holes similar to those produced with partially hydrogenated soybean oil; star shape is not a criterion with yeast-raised donuts. Oil weeping was lowest with donuts fried in partially hydrogenated soybean oil and second lowest with high oleic soybean shortening.
High oleic soybean shortening produced donuts similar in texture, interior grain, spread, height and size to partially hydrogenated soybean oil in both cake and yeast-raised donut frying studies.
Oil weeping is when oil leaches out of the donut providing an oily, possibly soggy, taste and mouthfeel. It can lead to inconsistent covering of glaze or powdered sugar. Additionally, excessive weeping results in undesirable greasy and stained packaging.
As determined by a trained sensory panel, high oleic soybean shortening performed most similarly to partially hydrogenated soybean oil in a sensory evaluation of color, mouthfeel and texture. While high oleic soybean shortening absorbed slightly more fat than partially hydrogenated oil, optimization of interesterification conditions and fatty acid composition can modify the absorption characteristics of high oleic soybean shortening to achieve lower fat absorption.
Shortening Performance
Total polar materials (TPM), a measurement of oil fry life, rises as oil is used. Therefore, the lower the TPM rise and overall TPM content, the better.
The TPM of high oleic soybean shortening was similar to partially hydrogenated soybean oil and significantly outperformed conventional soybean shortening and the palm/soy blend.
Partially hydrogenated soybean oil had the lowest degradation rate by p-Anisidine value of all oils tested. Due to significantly lower levels of polyunsaturated fatty acids, high oleic soybean shortening and the palm/soy blend outperformed conventional soybean shortening. p-Anisidine values quantify secondary oxidation compounds. These secondary oxidation compounds are converted to TPM, resulting in a reduction in oil quality. In addition to increasing the viscosity of the frying oil, these tertiary polymers tend to accumulate on the sides of the fryers resulting in hard-to-clean residues and undesirable fryer down time.