Effects of a brief blanching process on quality, safety, and shelf life of refrigerated cucumber pickles

Authors: Lafountain, Lisa; Johanningsmeier, Suzanne; Breidt, Frederick; STOFOROS, GEORGE - North Carolina State University; PRICE, ROBERT - Former ARS Employee

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2022
Publication Date: 4/1/2022
Citation: LaFountain, L.J., Johanningsmeier, S.D., Breidt, F., Stoforos, G.N., Price, R.E. 2022. Effects of a brief blanching process on quality, safety, and shelf life of refrigerated cucumber pickles. Journal of Food Science. 87(4):1475-1488. https://doi.org/10.1111/1750-3841.16112.
DOI: https://doi.org/10.1111/1750-3841.16112

Interpretive Summary: Refrigerated pickles do not undergo thermal processing, which can leave them vulnerable to microbial contamination. This study illustrates that adding a brief blanching step in refrigerated pickle processing can reduce indigenous microbiota without negatively impacting quality attributes. This blanching process could assist pickled vegetable manufacturers in providing additional safeguards for consumers, while maintaining a high-quality product.

Technical Abstract: Refrigerated pickles are characterized by crisp, crunchy texture, opaque flesh, and fresh flavor. Typically produced without a thermal process, microbial safety relies on preventive controls, brine composition, and sufficient hold time prior to consumption. We hypothesized that brief blanching of whole cucumbers prior to pickling could provide an additional hurdle for pathogenic microbes without negatively impacting finished product quality. Blanch treatments (15, 90, or 180 s) in 80°C water were conducted in duplicate on two lots of cucumbers prior to cutting into spears, acidifying, and storing at 4°C. Enumeration of total aerobes, lactic acid bacteria, and glucose-fermenting coliforms was conducted for fresh and blanched cucumber. Texture, color, cured appearance development, and volatile compound profiles were analyzed for fresh and blanched cucumber and corresponding pickle products during refrigerated storage. The 90 s blanch consistently achieved a minimum 2-log reduction in cucumber microbiota and a predicted 5-log reduction of Escherichia coli O157:H7 up to 1.1 mm into the cucumber fruit. Blanching had no impact on tissue firmness during refrigerated storage for 1 year (p > 0.098). There were no differences in flavoractive lipid oxidation products (E,Z)-2,6-nonadienal and (E)-2-nonenal, and consumers (n = 110) were unable to differentiate between control and 90 s blanched cucumber pickles stored for 62 days. Exocarp color and mesocarp opacity were preserved by the blanching treatment, potentially extending product shelf life. This method offers processors an option for reducing the risk of microbial contamination while maintaining the quality attributes associated with refrigerated cucumber pickles.