Bakery boosts: Upcycled tea leaves and coffee grounds elevate nutrition and shelf life in cakes

25 Sep 2023 --- Spent tea has had a long history and vital role in traditional cuisines, but researchers have found a novel approach to including the ingredients in baking. A new study, featured in ACS Omega, demonstrates the incorporation of spent tea leaves and coffee grounds into sponge cake batters, resulting in a snack that enhances nutrition and extends shelf life.

Tea and coffee, two beverages outranked only by water in global consumption, according to the American Chemical Society, are renowned for being rich sources of antioxidants, fiber and essential nutrients such as potassium and calcium.

However, the traditional brewing process often leaves these valuable compounds behind in the spent tea leaves or coffee grounds. 

A modern culinary innovation
Abdelrahman Ahmed, Khaled Ramadan and Mohamed Mahmoud, along with their colleagues from King Faisal University, Saudi Arabia, ventured into uncharted territories by including spent tea and coffee powders in sponge cakes.

To formulate the enriched powders for the treat, the team brewed either black tea or Arabica coffee. The resultant leftover grounds or leaves were meticulously rinsed, dried and pulverized before being integrated into the sponge cake batter, creating variants with 1%, 2% or 3% powder. 

This process resulted in cakes exhibiting heightened antioxidant activity and enhanced concentrations of crucial nutrients. 

The fortified cakes developed by researchers showed increased shelf stability, with reduced microbial growth. (Image credit: Mohamed Mahmoud, King Faisal University).

These fortified cakes were not only comparable in taste and texture to their traditional counterparts but also demonstrated increased shelf stability, with reduced microbial growth observed after up to 14 days of storage.

However, it was observed that cakes with higher amounts of spent tea powder were rated lower by a sensory panel primarily due to their darkened appearance, whereas those with spent coffee powder received scores closer to the control loaves.

A treasure in ancient palate
In traditional Asian culinary practices, spent tea plays a notable role as a versatile ingredient. Varieties such as gyokuro and sencha green tea leaves find their way into traditional Asian salads and hot dishes. 

Varieties such as gyokuro and sencha green tea leaves find their way into traditional Asian salads and hot dishes.One of these traditional cuisines is chazuke, a simple Japanese delicacy that involves pouring green tea, dashi or hot water over cooked rice. When properly stored, spent tea can often outshine its fresh counterparts as an ingredient.

Lei cha, a traditional tea-based soup, holds a cherished place in the culinary traditions of countries such as China, Malaysia and Singapore. The soup can also be used as a paste in classic dishes like Hakka tea rice, achieved by blending spent tea with a variety of vegetables and toppings, including nuts and tofu. 

Health benefits of coffee grounds
Meanwhile, coffee grounds have embarked on a culinary journey in the West, enriching an array of food products, from smoothing out shakes to elevating the taste of cookies and brownies. 

Research has shown that spent coffee grounds are a natural source of antioxidants, insoluble fiber, essential amino acids and low glycemic sugars. Furthermore, these grounds exhibit resilience in the face of thermal food processing and the digestion process, rendering them an intriguing and safe ingredient in various culinary applications.

Using spent coffee grounds as a food ingredient in innovative bakery products might not only enhance nutrition and taste but also hold the promise of lowering the risk of chronic conditions like obesity and diabetes.

By Sichong Wang