Effects of processing on onion skin powder added extrudates

Area of Science:

• Food Science and Technology
• Nutritional Biochemistry

Background:

• Fruit and vegetable by-products can improve the functional properties of extruded foods.
• Onion skin, a rich source of quercetin and fiber, is an underutilized industrial waste.
• Incorporating onion skin powder (OSP) offers a strategy to enhance the nutritional value of extruded products.

Purpose of the Study:

• To investigate the impact of incorporating onion skin powder (OSP) at varying levels (3%, 6%, 9%) on the functional properties of extruded wheat flour.
• To evaluate the effect of the extrusion process on accessible quercetin, total phenolic content, and antioxidant activity.
• To analyze the carbohydrate digestibility of the OSP-enriched extruded products.

Main Methods:

• Wheat flour was supplemented with OSP at 0% (control), 3%, 6%, and 9%.
• Extrusion processing was applied to the samples.
• Quantification of accessible quercetin (LC-MS/MS), total phenolic content, antioxidant activity, and carbohydrate digestibility was performed.

Main Results:

• Increasing OSP levels significantly increased quercetin content, with extrusion enhancing quercetin accessibility.
• Total phenolic content decreased post-extrusion, but antioxidant activity remained unaffected.
• Extruded products exhibited high rapidly available glucose content, and OSP addition did not alter carbohydrate digestibility.

Conclusions:

• The extrusion process can enhance the accessibility of bioactive compounds like quercetin from OSP in extruded products.
• Onion skin powder shows potential as a functional ingredient to boost antioxidant properties.
• Further optimization of OSP levels is recommended for maximizing functional compound benefits in extruded foods.