Controlled fortification of apple chips by osmotic dehydration

Fruits and vegetables are a crucial part of human diets due to their abundant nutritional content. But their moisture content can be as high as 85% (wet basis), making them highly perishable. Drying is the most prevalent method for reducing moisture content in foods for the purpose of preservation. Unfortunately, drying is also the most energy intensive unit operation in industrial processes; also, a long exposure of food products to high temperatures inevitably causes a degradation of food quality, especially the nutritional value. Osmotic dehydration (OD) is a phase change free, low temperature method of moisture removal, and it is often used as a pretreatment method before a finish drying process, such as hot air drying, for reducing work load in drying process, thus reduce energy consumption and product degradation. A unique advantage of OD is that it can be used to introduce health-promoting molecules into food material, thereby functioning as a food fortification method. However, moisture removal by osmosis is a relatively slow process, and the increased sweetness (due to the introduction of sugars through osmotic solutions) may alter the original taste of the food products and cause health issues. This study is aimed at developing an efficient OD-based method for the production of nutrition fortified dried apples while having less amount of sugar. Impregnation of bioactive compounds into apple tissue in OD process was investigated by using hypertonic fruit juices as osmotic solution. Two non-thermal techniques, vacuum and ultrasound treatment, were tested for improving mass transfer in OD process, as well as the effect on calcium impregnation. Pea protein and inulin were employed as additives to reduce sucrose uptake in OD process. The results indicated that osmotic pressure gradient between food materials and osmotic solution in OD process can be used to describe mass transfer in the process; bioactive compounds and minerals (such as calcium) can be impregnated into food products in OD processes; vacuum and ultrasound treatments can enhance moisture removal and solid gain in OD process, and they can also enhance fortification processes; using large molecular weight carbohydraties and water soluble proteins as additives to osmotic solution can reduce sucrose uptake in OD processes, thus reduce sugar content in final product. In all, a well designed OD process can be used as a fortification method to impregnating health promoting substances into food materials.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Agricultural & Biological Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2022

Author dc:creator

• Wang, Xiaojuan

Contributors dc:contributor

• Feng, Hao
• Wang, Xinlei
• Lee, Youngsoo
• Rausch, Kent

• Food fortification
• Osmotic dehydration
• Osmotic pressure
• Mass transfer
• Ultrasound treatment
• Vacuum treatment

Statement dc:rights

• Copyright 2022 Xiaojuan Wang

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/115873

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F115873