Effects of Some Weak Acids and Moringa oleifera Leaf Extract Powder on the Colour of Dried Apple

Abstract

This study aimed to find alternatives to sulphite as a preservative for dried fruits. Granny Smith apples were sanitised in a 200 ppm sodium chlorite solution, de-cored, peeled, and cut into slices. The sliced apples were pre-treated/dipped in a water solution containing the three weak acids, namely, ascorbic acid (AA), citric acid (CA), and potassium sorbate (PS) as well as Moringa oleifera leaf extract powder (MOLEP). A screening fractional factorial experiment consisting of five independent variables (AA, CA and PS, time and temperature and MOLEP) constrained at their upper and lower levels (AA: 0.5 to 2.0%, CA: 0.3 to 2.0%, MOLEP: 0.1 to 0.2%, time: 7 to 15 h and temperature: 57 to 70 °C) were evaluated for their effect on the colour of the dried sliced apples. An increase in the concentration of the CA significantly increased the lightness (p = 0.05) and decreased the redness (p = 0.0022) of the dried apple slices. AA and PS did not impact the lightness of the dried sliced apples. A dipping solution of citric acid at 2.0%, Moringa oleifera leaf extract powder at 0.1%, and drying time of 7 h at 70 °C effectively minimized the discolouration of the dried sliced apples.

Storage Stability and Consumer Acceptability of Dried Apple: Impact of Citric Acid, Potassium Sorbate and Moringa oleifera Leaf Extract Powder

“…A study by [ 13 ] showed that a pre-treatment with 2.0% CA, 0.1% MOLEP and a dehydrating for 7 h at 70 °C minimized the browning of the dried sliced apples. Even though, according to the study by [ 13 ], citric acid (CA) was more effective than potassium sorbate (PS), it was thought it may assist to increase the storage period of the dried apple slices. However, nothing is known about the impact of the dipping solution with potassium sorbate on the shelf-life and consumer acceptability of dried sliced apples.…”

Special Issue: Properties and Processing Process of Flour Products

“…Maphosa et al [4] produced a nanocomposite from Bambara groundnut starch and soluble dietary fibre, which was used in stabilizing beverage emulsions at significantly lower concentrations than Bambara groundnut soluble dietary fibre. Arendse and Jideani [5] developed alternative preservatives to sulphite by minimizing the enzymatic browning of dried sliced apples. The study shows that a dipping solution of 2% citric acid in combination with 0.1% leaf extract of Moringa oleifera minimized the discolouration of dried apple slices.…”