What causes kava spoilage?

Kava drinkers often ask, “How long can I keep my kava in the fridge?” Luckily, a study by researchers at the University of Hawaii at Moana has tackled this question. They collected samples of both fresh and dry kava beverages from kava bars in Honolulu to quantify and identify bacterial growth.

The researchers refrigerated the kava beverage samples and checked them after 0, 3, and 6 days. They discovered different types of bacteria, yeasts, and mold in kava, but they mainly focused on Pseudomonas Spp bacteria, which is known to be the main cause of food spoilage in fresh foods stored in aerobic refrigerated conditions, and lactic acid bacteria (LAB).

The study found that when kava is left uncovered in the fridge, the bacteria group Pseudomonas, lactic acid bacteria (LAB), yeast, and mold can increase considerably. LAB was possibly responsible for fermenting carbohydrates into lactic acid, which increases the acidity of kava and gives it a sour flavor. Yeast and molds also increased significantly over the 6-day period in refrigeration, contributing to spoilage. The study suggests that vacuum sealing the container can prevent some spoilage caused by Pseudomonas bacteria by removing oxygen.

Summary:
When stored in the fridge, kava still has a limited shelf life. It was once believed that kava had widely-ranged antimicrobial properties, but this study suggests otherwise. Testing conducted at 0, 3, and 6-day intervals showed an increase in bacteria, yeast, and mold counts, which can cause food spoilage. While none of the levels were unsafe after 6 days, the taste and smell of the kava deteriorated significantly.

Dong, J., P. Kandukuru, A. S. Huang, and Y. Li. 2011. “PCR-DGGE Analysis of Bacterial Community Dynamics in Kava Beverages during Refrigeration.†Letters in Applied Microbiology 53 (1): 30–34. https://sci-hub.se/10.1111/j.1472-765X.2011.03065.x