Sweetpotato chip texture and fat content: Effects of enzymatic modification of cell wall polymers

Authors: Allan, Matthew; Johanningsmeier, Suzanne

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/6/2022
Publication Date: 9/1/2022
Citation: Allan, M.C., Johanningsmeier, S.D. 2022. Sweetpotato chip texture and fat content: Effects of enzymatic modification of cell wall polymers. Journal of Food Science. 87(9):3995-4008. https://doi.org/10.1111/1750-3841.16267.
DOI: https://doi.org/10.1111/1750-3841.16267

Interpretive Summary: Sweetpotato chips are an increasingly popular snack, but little is understood on how to control texture and fat contents. Raw sweetpotato slices were treated with enzymes to selectively breakdown cell wall polymers before frying to investigate the impact of sweetpotato composition on chip texture and fat contents. Alterations to pectin affected chip texture while breaking down hemicellulose components reduced chip fat content. Therefore, sweetpotato cell wall composition should be considered when selecting cultivars and processes for producing sweetpotato chips.

Technical Abstract: Impacts of cell wall polymers on sweetpotato chip texture and fat content were investigated through enzymatic modification. Covington sweetpotato slices were treated with cellulase, hemicellulase, pectinase, pectin methyl esterase, protease, the enzyme blend Viscozyme, or no enzymes (control) at 40–45°C for 0.5–2 h. Treated slices were blanched, dried, and fried in triplicate per experimental condition. Breaking forces of 20 chips per frying replicate were measured followed by chip fat, moisture, sugar, alcohol insoluble solids, glass transition temperature, and color analyses. Untreated slices from each batch (daily check) were fried and analyzed to account for starting material variability. Viscozyme and protease-treated chips had the greatest reduction in breaking force from untreated chips (-30.9% and -23.7%, respectively), while pectin methyl esterase-treated chips had the lowest reduction in breaking force (-9.0%). Chips treated with Viscozyme for 2 h were 6.7-6.3 percentiles lower in fat than the control. Principal component analysis elucidated that chip breaking force was associated with unfried slice puncture force, alcohol insoluble solids, and chip color, and chip fat content was inversely associated with maltose content and glass transition temperature. Breaking down multiple cell wall polysaccharides or structural proteins weakened chip textures, while strengthening the pectic fraction resulted in harder chips. Chip fat reduction also occurred when multiple cell wall polysaccharides were broken down. Therefore, cell wall polymers impact sweetpotato chip texture and fat contents, and their attributes should be considered when selecting cultivars and processes for sweetpotato chips.