Final report for the CORE Organic Plus funded project “Drying, Juices and Jams of Organic Fruit and Vegetables: what happens to Desired and Non-Desired compounds? FaVOR-DeNonDe” Period covered: 30 March 2015 - 29 March 2018

Summary

The main activity was related to the description of qualitative data on commonly consumed fruit (strawberry, plum, apple) and vegetables (tomato and sweet bell pepper) along some processing chains (jam, juices and dried products), pointing out the role of different sources of variability, such as the type of cultivation (Conventional, CONV or Organic, ORG), the different cultivars, the sampling year, and the type of processing. A particular attention has been paid on the type of processing, where the use of innovative plant was performed, in comparison with traditional or home-made processing typologies. This for the need, especially for local and small farmers, of small and simple plants to process agricultural products, in order to add value for their productions, for achieving high quality and safe products.
For this scope three types of approaches for processing were used:
- a miniaturized multifunctional processing line (MT), already validated in previous Projects, in comparison with home-made technique (HM) for jam strawberry production;
- a pneumatic press, a rack-press and a belt-press compared for the production of apple juices;
- an innovative drier, completely supplied by solar energy (SUN) compared with a traditional forced air oven-drier (OVEN) was used for the production of prunes, dried tomatoes and sweet bell peppers.
The list of analyzed samples is shown on the Final Report Document:
SCHEME OF ANALYZED SAMPLES (ORG is Organic, CONV is Conventional)
The processed samples were produced in open field on two consecutive sampling years (2015 and 2016), on experimental fields. A third year of sampling was added, considering the evaluation made on raw products.
Moreover, for tomato and sweet bell pepper, the production made from open fields of private organic growers, was considered, so obtaining samples in two consecutive years (2016 and 2017).
Hence, a further comparison of the quality indexes was made on raw products in three consecutive years (2015, 2016 and 2017).
The control samples were represented by the lyophilized material, generally referred as “raw” or “not treated” sample.
The considered qualitative data regarded "Desired" and "Non Desired" compounds, being the desired ones those potentially healthy and tasty for humans, such as phytochemicals, antioxidants and volatiles, and the non desired some anti-nutritional traits, such as the mycotoxin patulin and the presence of allergens. The samples were also evaluated by their sensory properties, by using a trained panel.
As for the allergen analysis, they were analyzed by indirect competitive ELISA for determination of Bet v 1-related protein, or pathogenesis-related proteins (PR-10), causing birch pollen related fruit allergies.
A big amount of data was collected, with a consequent variability among them. The general consideration about desired compounds that can be made is that, if a well detectable difference in composition has been found in raw product, this difference was also retained in the processed one, with the processing technique strongly influencing the qualitative parameters of the final products. In this context, better results in terms of antioxidant presence were found for:
- apple juices obtained from belt-press;
- strawberry jams obtained with miniaturized small-scale plant;
- prunes, tomatoes and sweet bell pepper obtained with oven drying.
On the other hand, it has to be pointed out that processing methods causing a lower retention on the phytochemical contents often show a better response in term of sensory properties, as found in apple juices and in solar-dried samples of strawberries, plums and tomatoes.
Some differences were found among the assayed cultivars, and, finally, among the comparison of the system of cultivation (ORG vs CONV).
Specifically, the system of cultivation mainly influenced the antioxidant content in apples of traditional cultivars of Estonia obtained from aged plants; as for strawberry, it was found an higher amount of antioxidants in organic samples in one year of three, and a significant increase in ascorbic acid was found in the assayed local variety of organic bell pepper, in all three years, but not in the corresponding commercial hybrid. On the other hand, the plum cultivar Jubileum, assayed from Denmark and Norway in two years, resulted not adapted for organic cultivation for the content in ascorbic acid, constantly giving lower indexes in all samples in comparison with fruits from conventional cultivation.
As regards the influence of the sampling years, in samples of apples, plums, tomatoes and sweet bell pepper, a tendency to an increase in phytochemicals and antioxidant indexes was detected in 2016 with respect to 2015 samples, due to the very different climate conditions of these two years.
Interestingly, for the non desired traits, no clear relationship was found between the presence of patulin and allergens for the systems of cultivations, but significant variations were found with the difference in processing technique, with the sampling years and with the assayed cultivars. Interestingly, for some apple cultivars from Estonia low levels of the allergen Mald1 were detected.
Concluding, the sources of variability among the analyzed samples gave, in order of influence, the following ranking:
- 1. Processing techniques;
- 2. Years of sampling;
- 3. Cultivars;
- 4. Growing methods.