Preserving Juice from Industrial Beets Using Organic Acids

Efficient and cost-effective methods are necessary to preserve the sugars in beet juice to enable year-long end-processing into bioproducts. Organic acids are effective preservatives that could be produced from a fraction of the sugars in beet juice to preserve the remaining sugar fraction. The preserving acids and remaining sugars may then serve as fermentation substrates in other bioprocesses. The effectiveness of organic acids to preserve sugars in beet juice has not been reported. Therefore, the objective of this work was to screen several potentially effective organic acids for their ability to accomplish sugar preservation in beet juice. Six organic acids (acetic, butyric, citric, lactic, propionic, and pyruvic) were used in three storage experiments in which beet juice was stored at four pH levels (5.3, 5, 4.25, and 3.5) and at 22.5°C for 21 to 38 days. Butyric, citric, and propionic acids helped preserve at least 92% of sugars at pH = 4.5, and lactic acid only at pH 3.5. Meanwhile, acetic and pyruvic acids helped preserve up to 88% of sugars at pH 3.5. Changes observed in the stored beet juice mainly occurred within the first 10 days, and thereafter the juice appeared stable. Before the storage experiments, the response of beet juice pH to different amounts of added acid was evaluated. There was an exponential decrease in pH as the molar ratio of acid increased. Future research should focus on developing methods to achieve the desired storage conditions and validating storage techniques through final fermentations of stored juice. Keywords: Acidification, Beta vulgaris, Fermentable sugars, Organic acid, pH, Refractometric dissolved solids, Sugarbeet.