From food waste to functional ingredients: Study finds potential to transform cashew apple pulp

27 Feb 2023 --- The underutilized cashew apple pomace (Anacardium occidentale) has nutritional, environmental and economic benefits, according to a review of 26 studies. Sensory evaluations support incorporating cashew apple pomace in several products, but manufacturers must choose appropriate food products and optimize the formulation.

Pomace or pulp is the material that remains after processing cashew apples into juice. The wet pomace can also be dried to create a pomace powder. 

NutritionInsight spoke with one of the review’s authors, Nathalie van Walraven, MSc nutritional sciences from the Hebrew University of Jerusalem, Israel, who hopes the study raises awareness of the fruit. 

“Currently, many people don’t know that there even is such a thing as a cashew apple. Of course, the hope is that this ‘fruit’ will be utilized instead of wasted.” 

She adds that the cashew apple pomace is a versatile ingredient and “can be incorporated into a wide variety of products.” 

The authors note that 36.9 million tons of cashew apples are produced worldwide, but only small amounts are used to make juice. 

Food applications
The reviewed studies used cashew apple pomace as a food ingredient and performed sensory analyses. Food products incorporating the pomace included burgers, meat substitutes, baked goods, local Brazilian dishes, jam, croquettes and a cereal-based extrudate. 

The review found that cashew apple pomace has nutritional, environmental and economic benefits. “In the studies reviewed, the food products that received the highest scores were meat or alternative meat products,” notes Van Walrave. She adds that pre-tests likely contributed to this factor, as did the use of professionals from gastronomy and focus groups for recipe development. 

“What products to incorporate should also be adjusted to where the product will be consumed. There are different food traditions and norms that need to be taken into account for success.”

Adding cashew apple pomace (powder) was found to lower the moisture content in some cases, reduce fat and protein content, increase ash and carbohydrates and lowered pH. 

Processing conditions can influence product composition. For example, washing the pomace increased pH and fermenting cashew apple pomace powder added to its protein content. 

Most studies found that participants preferred products with lower cashew apple pomace (powder) concentrations. If products only substituted low levels of its ingredients for the pomace, organoleptic qualities were comparable to the control product. 

In some cases, scores improved by adding the powder, such as chicken patties and cereal-based extrudates. 

Challenges to overcome 
Van Walrave explains different pieces need to come together to make the pomace commercially available and notes that investments are required to address these aspects. 

From the producers’ side, infrastructure needs to be developed so that the cashew apples can be collected and then processed, for example, into juice or other beverages and then utilized in food products. 

She warns that product development and marketing also need to improve. Without this, “there will not be an incentive for the farmers to collect the apples.” 

However, setting-specific best practices still need to be developed.

The article further states that wasting this potential food source is attributed to numerous factors, such as inadequate knowledge and a lack of processing skills and post-harvest technology.

The fruit’s high perishability limits its potential, adds Van Walrave. Moreover, cashew does not grow everywhere and in many of the cultivation areas the cashew apple has not been prioritized in studies. Manufacturers must choose appropriate food products and optimize the formulation, stress the authors. 

However, she adds that much research has been done in Brazil, where cashew is cultivated.  

According to the authors, well-designed clinical trials must be conducted with adequate sample size and unequivocal evidence of safety. This could help establish the pomace’s contribution to health beyond basic nutrition. 

Nutritional benefits 
The study published in Critical Reviews in Food Science and Nutrition also compared the nutritional benefits of whole cashew apples and wet and dry cashew apple pomace. The dry pomace had a lower moisture content but higher macronutrients. 

The review found the vitamin C content of cashew apple pomace higher than the concentration in lemons, mandarins, oranges and peppers. However, studies found significant differences (between 6 and 900 mg/100g for dry pomace). 

Protein content reached up to 13.8%, higher than commonly found in fruit peel flour (3-6%), while lipid content was relatively low. 

Dietary fiber content varied considerably in the reviewed studies (35-79%) but was higher than comparable products, such as dried peach pomace (30.7%). 

Although levels of soluble dietary fiber (8%) were higher than those found in lemon pomace (6.7%), it was lower than for carrots (22.7%), apples (20.3%) and orange pomace (13.4%). 

By Jolanda van Hal