393: Kombucha From Carrot Processing By-Products: An Upcycled Food

Introduction

FAO estimates that one-third of edible food produced for human consumption is wasted annually. Carrot pomace, a byproduct of carrot juice production, is a potential source of fermentable sugars. Kombucha, a functional beverage made through the fermentation of sweet tea using a symbiotic culture of bacteria and yeast (SCOBY), offers a promising way to repurpose these by-products. This study explores the use of carrot pomace as a fermentable sugar source for kombucha production, aiming to reduce food waste.

Methods

Carrot pomace was treated with commercial enzymes: cellulase (FoodPro BSL), cellulase complex (FoodPro CBL), and glucoamylase (FoodPro CGL), all manufactured by Danisco. Vinegar was used to adjust the pH for cellulase and glucoamylase treatments. Individual and combined enzyme treatments were tested, and samples were incubated for 0 to 120 minutes at 60°C. After enzyme treatment, inactivation occurred at 90°C. Reducing sugars were measured using the dinitrosalicylic acid method.

Kombucha was prepared using each enzymatically treated carrot pomace, along with a control batch without pomace. All batches contained water, green tea, kombucha starter, and SCOBY. The control kombucha had 6% sugar, while the carrot pomace-based kombucha had no added sugar. Fermentation took place at 23°C for 2 to 5 days, stopping when the samples tasted sour. Brix, pH, titratable acidity (TA), and Brix/TA ratios were measured.

Results

Reducing sugars from the cellulase + glucoamylase treatment increased from 8 to 26 mg/ml from 0 to 60 minutes, before slightly decreasing at 90 and 120 minutes to 20 mg/ml. Still this treatment had the highest reducing sugar value (20 mg/ml) at the longest incubation time (120 min) which was 2.5 times higher than the control at the same incubation time (8 ml/min).

The Brix/TA ratio, as an indicator of the sensory desirable kombucha’s sweet-sour balance, was 0.8 to 1.3 for carrot pomace kombucha after just 2 days, while the control needed at least 5 days.

Significance

Repurposing carrot processing by-products into kombucha reduces food waste while providing a nutritious, eco-friendly beverage. This approach supports a circular economy by integrating nutrient-rich by-products, promoting sustainability and environmental conservation.

Authors: D. Mom, S. Amin and R. García-Torres