Smart Drying Opportunities

Faculty Development Competitive Research Grant Program 2018-2020

It is an undisputable priority to consume apples and melons as fresh products; however, the processed products such as apple juice, jams, marmalade, pastille and sun-dried melon straps deserved their niches.
We suggest that the local ‘apple’ market has a niche for the specific product such as a high quality apple rings and melon chips snacks which might be benefited in the quite numerous situations like air flight, journey by train, a quick bite etc.
The project aims to develop specifics of the convective drying process for producing high quality apple and melon snacks without adding preserving agents and sugar. The key novelty is in utmost comprehensive exploitation of the specific feature of Kazakhstan climate, namely the low humidity air. Application of a dry and extra-dry air allows carrying out the convective drying process at the ambient temperatures (i.e. without extra heating) which prevents loss of temperature sensitive components and results in a high quality final product with high content of valuable nutrients.
The objectives of the project are as follows:
1. Development of the specifics and regimes of the products convective drying process based on application of the air at low and extra-low humidity.
2. Obtaining of the high quality local dried products with competitive nutritious properties.
3. Design of the pilot dryer to produce the apple rings.
Scientific novelty is in application of reaction engineering approach (REA [1]) for prediction of drying rate of apple rings and melon chips.
Multiple technological novelties are as follows:
(a) fabrication of high quality puffy/soft apple ring snacks (not available at market);
(b) fabrication of non-sticky melon snacks (not available at market);
(c) contribution into ‘green’ technology as the process free from questionable conserving substances;
(c) energy saving drying process due to drying at ambient temperature and benefits of climate in Kazakhstan (plenty of dry air).
(d) contribution to sustainable development via process optimization and efficiency improvement thus reducing greenhouse gas emissions.
The expected social impact: contribution into list of healthy food. In the long term: creating new opportunities for food industry in Kazakhstan.
Literature review demonstrates a number of research papers focusing on different aspects of apples and melon drying techniques, for example [2-6]; surely the valuable information from literature will be taking into account under proposed Project. However, herewith we selected a final product design concept as a key navigator and driving force for our Project. In other words, we plan to focus our research namely on the specific aspects of drying technology that further lead us to the optimization of the desirable properties of the products which we have obtained under preliminary work. Hence, herewith we place the references and other information (photos) that directly relate to underpinning of the present Project. Project pre-history:
The employed in this Project concept for modelling drying was adopted in 2010 when PI of this Project met in the University of Nottingham Professor X.D. Chen and familiarized with his Reaction Engineering Approach method [1] of treating the drying processes. This approach indeed has a several advantages; in particular, it bridges experimental drying curves data with the Arrhenius fundamental equation in the evaporation term.
The second push came from experiments carried out in Malaysia (2012) by PI and his colleague Chong Gun Hean while testing the set-up designed to determine continuously the rate of drying when controlling and measuring in-situ air flow rate and inlet and outlet air humidity [7,8]. The inlet air RH humidity can be set to l% or lower. This set-up (Fig.1) made possible to dry out even the water melon samples (Fig.2): The third piece of rationale for the Project goes from outcomes of our experience we carried out in Nazarbayev University in attempts to obtain apple and melon snacks using a specific of the Kazakhstan climate, namely availability of relatively (say, 20- 30 % RH) dry air within days or weeks.
This self-motivated and self-financed research work (unpublished) yields some inspiring results, however the further R & D work is needed to be activated through a normal project process & management.
In short, the current ‘state-of-art’ with apple rings and melon chip snacks is as follows:
(1) there are crispy apple rings available in the market (Fig. 3), however they are fabricated under thermal overheating application which leads to loss of vitamins, specific nutrients and natural apple aroma.
(2) the consumers are offered the ‘soft’ apple rings (Fig. 4), however the manufacturers use the preservative agent (sulphur dioxide) and pack the product into a protective atmosphere.
(3) there no dried melon products available in supermarkets in Kazakhstan (we do not count home made products that can be purchased in the southern regions). At the same time, our apple rings samples (Fig.5) obtained by convective drying at ambient temperature are characterized by attractive appearance, rich apple aroma, good natural taste, but (at present) have a rather weak point, namely the apple rings might be found as rather with a hard texture (from a demanding customer point of view).
As to melon chips (Fig.5), these are quite soft and tasty, but we herewith we also face some ‘nuisance’, namely, undesirable stickiness of the melon pieces (Fig. 6).
prevent undesirable shrinking due to generating an exterior surface ‘frame’ which leads to a puffy soft product. For example, the samples of ‘puffy & soft’ apply rings (Fig.7) were obtained by processing with ambient temperature but extra-dry air. Fig. 8 explicitly shows the difference in shape and appearance of the product (mushrooms) processed by conventional drying method and application of air with low humidity. The above mentioned drawback under this project we plan to fix and handle with application of extra-dry air (about 5% RH or less). Some preliminary experiments with extra-dry air demonstrate that such application has a potential to prevent undesirable shrinking due to generating an exterior surface ‘frame’ which leads to a puffy soft product. For example, the samples of ‘puffy & soft’ apply rings (Fig.7) were obtained by processing with ambient temperature but extra-dry air. Fig. 8 explicitly shows the difference in shape and appearance of the product (mushrooms) processed by conventional drying method and application of air with low humidity. The presented above ideas and results might serve as the starting point for the multi-purpose research project which aims to produce healthy products for the local and international market, the design of the pilot dryer for processing apple rings and melon chips, and the development of Reaction Engineering Approach [1] (hence determining the relevant activation energy values) in application with selected agriculture products.