What is it about?

Fruit juice concentrates (chokeberry Aronia or bilberry Vaccinium myrtillus L. orgine) or fruit by-products extracts from berry press cake may be used as osmotic substances. Are they appropriate alternatives to sucrose for osmotic dehydration? A leftover from bilberry juice manufacturing, bilberry press cake was supplied by Svantes Vilt & Bär (Harads, Sweden). We used apple variety Gala obtained from WULS-SGGW Experimental Field (Warsaw, Poland) as raw tissue in the osmotic dehydration experiments. Is osmotic dehydration (OD) an excellent alternative to creating new innovative apple products with distinctive final properties?

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Why is it important?

Peleg’s model for both proposed indicators (normalised water content NWC and normalised solids gain NSG) was adequate to describe kinetic curves of the process. In the case of the use of 80% bilberry press cake extract the NSG was very low but NWC was relatively high. Unfortunately, a low concentration of slightly concentrated fruit juices is not effective for dehydration of apples, but it may be sufficient to enrich the fruit with the desired colourants. Higher concentration of osmotic solution and a larger addition, especially of the concentrate of chokeberry juice, significantly affected the colour changes of dehydrated apples. Normalized solids gain NSG was positively correlated with brightness L*, chroma C, taste and softness but negatively with total colour change ΔE, colour hue h, colour as sensory descriptor. Changes related to mass transfer in dehydrated samples, i.e. reduction of water content NWC and penetration of osmotic substances NSG, have a direct effect on colour and sensory descriptions.

Perspectives

Fruit juice concentrates are the useful natural colouring agent in the fruit production. Considered osmotic solutions have a high potential for colouring and shaping sensory properties, since they contain, for example, a significant amount of polyphenols. The osmotic dehydration in the sugar solution with addition of berry fruit juice concentrates and by-product extract reduces the water content and increases solids gain, to changing colour, taste, softness and flavour of processed apples. The addition of 5 and 15% of berry fruit juices or extract to sucrose solution causes colour changes in semi-dehydrated product. The addition of extract from bilberry press cake can be successfully used in conjunction with a sugar solution.

Dr hab. Dariusz Piotrowski
Instytut Ogrodnictwa - Państwowy Instytut Badawczy

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This page is a summary of: The effect of adding berry fruit juice concentrates and by-product extract to sugar solution on osmotic dehydration and sensory properties of apples, Journal of Food Science and Technology, March 2019, Springer Science + Business Media, DOI: 10.1007/s13197-019-03658-0.
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