Identification of bacterial species on Lippia multiflora herbal tea leaves and the influence of steam pasteurization

Abstract

The consumption of herbal teas is an increasing phenomenon among tea consumers globally. Some of these herbal teas are not pre-treated to reduce their microbial load before consumption, and thus constitute a health risk to consumers. In this study, the effect of steam pasteurization, at [99°C for 2.5 min, on the microbial load of Lippia multiflora herbal tea leaves was evaluated. Microbial enumeration was conducted on potato dextrose agar, plate count agar, violet red bile agar, yeast peptone dextrose agar, and DeMan-Rogosa-Sharpe agar. Morphologically distinct colonies were isolated, sub-cultured and their Gram reaction recorded. These bacteria were identified to the species level using 16S ribosomal DNA sequence data. Most of the bacteria identified belonged to the genus Bacillus. One species each from the genera Pantoea and Kocuria was also identified, but only the Bacillus species survived the steam pasteurization treatment. Coliform bacteria detected prior to pasteurization were not detected after the steam treatment. Steam pasteurization reduced the microbial load from 10 4 to 10 2 c.f.u.g -1 and it is potentially an effective method to treat L. multiflora herbal teas prior to consumption. It is important to note that the steam treatment should complement good agricultural and hygienic practices rather than replace them, as some bacteria can survive this treatment.

Phenylethanoid glycosides as major antioxidants in Lippia multiflora herbal infusion and their stability during steam pasteurisation of plant material

“…A recent initiative to commercialise African plants for international markets has targeted L. multiflora for development. Under this initiative, steam pasteurisation of the dry leaves has been investigated to control microbial loads on the tea (Arthur, Cameron, Joubert, & Witthuhn, 2011).…”

<span lang="EN-GB" style="font-size: 12.0pt; font-family: Times New Roman"> The Survey of Microbial Quality of the Dry Sample, Extract and Brewing of some Medicinal Plants </span></p>

“…The results showed that herbs need boiling water for brewing, because water with lower temperature cause an increase in the number of microorganisms of the brewing. Arthur et al (2011) evaluated steam pasteurization and temperature treatments (99 °C for 5 min) on the microbial load of Lippia multiflora leaves. Results showed that pasteurization treatments reduced the microbial load and no Coliform was observed.…”