The use of apple pomace flour (APF) to fortify baked goods has been studied extensively for the past several decades.
Pomace is the byproduct of juicing, made up of about 54% pulp, 34% peels, 7% seeds, 4% seed cores and 2% stems that is either thrown out to biodegrade or used as livestock feed. It’s also often used to make jam and can be made into a flour.
It is high in dietary fibre and a rich source of polyphenolic compounds, along with antioxidant, anti-inflammatory, antitumor, antidiabetic and cardioprotective benefits. Products made from apple flour can also be gluten free, depending on its ratio with other flours like wheat flour.
However, a cost-effective method to produce the flour at industrial scale has essentially been out of reach.
High water content
APF has a high water content of around 75%, significantly more than wheat flour. While the porous structures developed within the apple product’s cell walls during the dehydration process allows for easy and complete rehydration, it means bakers have to use more water than is typical to create a workable dough.
However, the removal of its water content without affecting its nutritional and functional properties has been a major obstacle in commercialising it on an industrial scale.
To date, various drying techniques have been tested, but most are time- and energy-consuming.
Recently, though, an efficient low-cost drying method was developed to dehydrate AP on an industrial scale, which significantly reduces time and energy.
Following this, the November 2019 study published in the MDPI journal Foods looked into cookies fortified with APF.
“As ready-to-eat, quite durable products with long shelf life, cookies are very popular snacks. In addition, they represent a matrix suitable for fortification, thus providing an opportunity for the intake of important nutrients,” wrote the study’s authors.
“Due to the increasing incidence of various metabolic disorders, obesity, and gluten intolerance, there is an interest in developing fortified products with a high content of dietary fibre and antioxidants.”
The scientists experimented with various ratios of wheat flour to pomace flour in industrial settings.
The effect of wheat flour substitution with 25%, 50% and 75% of fine and coarse APF was studied during production on an industrial scale and after one year of storage.
Bulk and tapped density, swelling, water and oil holding capacity, solubility and hydration density of both fine and coarse APF were compared.
Ticking all the boxes
The researchers found coarse APF performed better in respect to sensorial properties, content and retention of dietary compounds and antioxidant activity.
The cookies with a 50% substitution of coarse APF contained 21g/100 g of dietary fibre and several times higher polyphenolics and flavonoids, as well as antioxidant activity than control cookies, while creating an intensely fruity aroma and crispy texture that would be positively received by consumers.
The dietary fibre content, alone, is a significant benefit, given the Dietary Guidelines for Americans, which recommend that adults consume between 28g to 34g of fibre per day. Currently, the average American adult only gets about 15g, according to the National Academy of Medicine.
Additionally, the researchers found that incorporating APF extended a product’s shelf life.
The study – which was supported by cookie company Gold Kusadak, and juice producers Fruvita and Sunny Delight – has paved the way for new business opportunities for both the bakery and apple industries.
Upcycling the byproduct of juicing ticks many consumer boxes, including reducing waste, creating more nutritional shelf-stable baked items and possibly even confronts food instability.
Authors: Snežana Zlatanović, Ana Kalušević, Darko Micić, et al
Foods 2019, 8(11), 561; https://doi.org/10.3390/foods8110561