Waste generated from apple juice or cider processing, often referred to as apple pomace, contains nutrients and bioactives that may be used as a nutritional aid for diet-induced metabolic complications, argued a team of researchers from West Virginia University and University of the Ozarks.
Their paper, published on Saturday in the Journal of Functional Foods, investigated how the livers of rats fed a so-called Western diet (high in calories from fat and carbohydrates) reacted to supplementation of apple pomace.
In rats whose diets contained the apple pomace mixture, the researchers observed improvement of palmitic and oleic acid transportation from the fat deposited in the liver, as well as improved antioxidant status—both of these are common indicators of suppressed non-alcoholic fatty liver disease (NAFLD) progression.
While positive results from rat studies cannot directly be applied to human health, the benefits seen in rats suggest future studies in humans are warranted.
“Based on the current animal study, absence of detrimental effect on liver health while attenuating NAFLD progression to [non-alcoholic steatohepatitis] NASH induced by Western diet consumption indicates apple pomace is a potential beneficial, and sustainable functional food for human consumption,” they wrote.
Reducing food processing waste
Over half of harvested apples are processed into beverages, and as the most widely consumed fruit in the United States, beverage processing creates a significant amount of waste.
“Apple pomace disposal is costly and is an industrial waste product that contributes to environmental pollution,” the researchers wrote.
“Apple pomace can be a sustainable food source for a growing population by repurposing processing waste as a functional food which decreases costs associated with disposal and reduces environmental pollution,” they added.
The researchers used 32 female Sprague-Dawley rats and randomly divided them into four groups with eight rats in each.
The first group of rats were fed a standard purified rodent diet, the second group fed a standard diet with 10% weight substituted with freeze-dried apple pomace, a third group fed a Western diet, and the fourth group fed a Western diet with 10% of weight substituted with freeze-dried apple pomace.
Rats had full access to their assigned diets and deionized water, meaning they can eat and drink whenever they wanted throughout eight weeks.
Food intake was measured, and diets replaced every other day while the water was replaced weekly. At the end of eight weeks, rats were fasted overnight and euthanized by carbon dioxide inhalation.
The liver was then extracted, weighed, flash frozen and analyzed.
The apple pomace used in the study came from locally grown Gala and Honey Crisp varieties, donated by the West Virginia-based Swilled Dog Hard Cider Company.
Source: Journal of Functional Foods
Published online ahead of print, https://doi.org/10.1016/j.jff.2019.103471
Apple pomace improves liver and adipose inflammatory and antioxidant status in young female rats consuming a Western diet
Authors: R. Chris Skinner, et al.