Apple Pomace in a Sustainable View

In addition to all of the sustainability on food systems studies, the recent three years, two different research groups have shown research alignment on the usability of apple pomace as known as a by-product in yogurt making with three published articles. Actually, the usability of apple pomace by-product has been searched for many years and recycle as a feedstock. Nevertheless, this way is not an efficient way due to the containment of valuable sources like hydroxycinnamic acids, flavonols, dihydrochalcones, and anthocyanins in it. 

Before starting to examine these articles, it is helpful to know what is apple pomace. During the pressing process of apple generally to apple cider, juices, or concentrate water and water-soluble compounds are removed, then the solid residue contains apple skin, pulp, and seeds as known as apple pomace. Significant researches show that the residue of how considerable value to not be a waste. 

Firstly, the main difference between the way of using the apple pomace as an ingredient of yogurt sample is that one is the direct use of freeze-dried apple pomace powder while the other one is the extract of the freeze-dried apple pomace powder. Fernandes, and etc.(Fernandes, Ferreira, Bastos, Ferreira, & Cruz, 2019) have chosen acidified hot water extraction way which is using boiling water with 1% acetic acid, pH 2.5, at a solid (dry weight) to a solvent ratio of 1:60 (g/mL)(Fernandes vd., 2019) (Fernandes vd., 2019). Also, some details revealed in this article to explain the extraction process, for example, owing to avoid the polyphenols thermal degradation choosing the extraction time 10 min rather than 1-2 h. 
In addition to acidified hot water extraction, to obtain more polyphenols than this method since polyphenols could also be present as complexes with carbohydrate, ultrafiltration, and solid-phase extraction methods have chosen. Then, antioxidant activity and anti-inflammatory activity parameters have examined for these extracts to report if there is any enhancing feature like nutritional properties or their stability along with the fermentation and final product yogurt rather than plain yogurt. From this point forward, Wang, etc. and Francis, etc. were experimented in many aspects like moisture content or the amount of the total phenolic composition of their apple pomace ingredient (Fernandes vd., 2019; Wang & Kristo, 2020; Wang, Kristo, & Lapointe, 2019). Wang mostly concentrated on the technological features of apple pomace fortified yogurt sample of applicability of it in industrial scale. It gives them to the point that search of rheological properties, changes in pH, titratable acidity and syneresis of the product during storage, and more, water holding capacity, firmness, consistency, cohesiveness, viscosity index parameters. Sincerely, the team published the other article, which was cumulative research of set type yogurt (Wang vd., 2019), after recognition of their findings of apple pomace powder increased the gelation pH and shortened the fermentation time indicates that eventually developed a firmer and more consistent yogurt gel. To sum up, the usability of apple pomace as an ingredient in fermented food products, especially yogurt products, has found that the potential to be incorporated, mainly a sustainable view and a view that aims to increase natural stabilizers in the food production sector.

Fernandes, P. A. R., Ferreira, S. S., Bastos, R., Ferreira, I., & Cruz, M. T. (2019). Apple Pomace Extract as a Sustainable Food Ingredient antioxidants Apple Pomace Extract as a Sustainable Food Ingredient. (June). 

Wang, X., & Kristo, E. (2020). Food Hydrocolloids Adding apple pomace as a functional ingredient in stirred-type yogurt and yogurt drinks. 100(July 2019). 

Wang, X., Kristo, E., & Lapointe, G. (2019). Food Hydrocolloids The e ff ect of apple pomace on the texture , rheology and microstructure of set type yogurt. Food Hydrocolloids, 91(December 2018), 83–91.