Microbial Growth and the Effects of Mild Acidification and Preservatives in Refrigerated Sweet Potato Puree

• Published in: Journal of food protection 2008-03, Vol.71 (3), p.639-642
• Main Authors: Pérez-Díaz, I.M, Truong, V.D, Webber, A, McFeeters, R.F
• Format: Article
• Language: English
• Subjects: acid tolerance; acid treatment; bacterial contamination; Biological and medical sciences; citric acid; cold tolerance; Consumer Product Safety; cooked foods; food contamination; Food engineering; Food industries; Food microbiology; food pathogens; food preservation; Food Preservation - methods; food preservatives; Food Preservatives - pharmacology; food storage; Fundamental and applied biological sciences. Psychology; General aspects; Humans; Hydrogen-Ion Concentration; Ipomoea batatas - microbiology; Listeria monocytogenes; Listeria monocytogenes - drug effects; Listeria monocytogenes - growth & development; potassium sorbate; potato pulp; pureed foods; Refrigeration; shelf life; sodium benzoate; Sodium Benzoate - pharmacology; sorbic acid; Sorbic Acid - pharmacology; steaming; storage time; sweet potatoes; Temperature; Time Factors; vegetative cells
• ISSN: 0362-028X; 1944-9097
• DOI: 10.4315/0362-028X-71.3.639

Refrigerated sweet potato puree is a convenient form of sweet potato that can be used as an ingredient in formulated foods. The microbiology of refrigerated sweet potato puree during storage for up to 5 weeks was evaluated. Because the puree was made by comminuting steam-cooked sweet potatoes before refrigeration, no naturally occurring vegetative bacterial cells were detected during a 4-week period of refrigerated storage at 4 degrees C. However, if postprocessing microbial contamination of the puree were to occur, contaminating microorganisms such as Listeria monocytogenes could grow during refrigerated storage. The effects of acidification or the addition of potassium sorbate and sodium benzoate on a population of L. monocytogenes inoculated into refrigerated (4 degrees C) sweet potato puree were determined. Inoculation of the refrigerated puree with L. monocytogenes at 10(6) CFU/ml resulted in a 3-log increase after 3 weeks storage of nonsupplemented puree. Supplementation of the sweet potato puree with 0.06% (wt/vol) sorbic acid or benzoic acid plus mild acidification of the sweet potato puree with citric acid to pH 4.2 prevented growth of L. monocytogenes during storage at 4 degrees C.