WP4. Optimising the production chain and product traceability
This WP aims to develop methods for strengthening consistency in apple production, so that fruits can be classified according to uniform groups with consistent and typical characteristics. The predictive methods should be based on the use of non-destructive systems monitoring fruit quality and growth/ripening in real time (DA-meter portable and stationary, DAFruit logger methods). The WP also aims to follow fruit traceability along the whole production chain up to the consumers and to validate novel non-invasive and user friendly techniques to asses fruit quality and compare it with consumer perceived quality.
WP4a New methods enhancing fruit homogeneity
There is here a connection between WP3 and WP4 represented by the definition of the ripening stage at harvest. The optimal harvest time will be assessed determining with accuracy the ripening stage reached by the fruits as affected by the cultural techniques used under field conditions (carried out jointly with CReSO-WP3). This will allow to define the homogeneity of the batch of harvested fruits and consequently decide in how many classes the fruits should be grouped. Developing methods for strengthening consistency is essential, so that fruits apparently homogeneous on the basis of the quality traits normally used (starch, SSC, FF, acidity, etc) can be more reliably classified in uniform groups with consistent and typical characteristics by the use of new non-destructive tools (DA-meter, DA Fruit Logger (DAFL)). The DA-Meter is a vis/NIR technique that does not require calibration, is not temperature-dependent, and can be used indifferently on all the cultivars. The instrument is characterized by a high degree of precision and allows to exactly define the physiological stage reached by the fruit, expressed as a ripening index (IAD = Index of Absorbance difference). The IAD is calculated as IAD = A670 – A720 where A670 and A720, are selected wavelengths near the chlorophyll-a absorbance peaks (Costa et al., 2003; Ziosi et al., 2008, Costa et al., 2009).The DA-Meter is also able to collect a consistent amount of data and can easily “instruct” a system to lead the distribution decision and can consequently be also used as a real time ”decision support system”. To have consistent amount of fruits characterized by homogeneous ripening stage, the portable DA-Meter could be implemented in a stationary version. To achieve this goal, a “head”, working on the DA-Meter principle, will be realized and positioned on existing commercial grading machine. It is expected that this stationary DA-Meter device will be able to analyze about 2-4 fruits/second. Once fruits will be grouped in classes of homogeneous ripening, according to the climacteric stage reached, a decision can be taken to establish the appropriate marketing or storage strategy (e.g. nearby or far away markets, normal or controlled atmosphere). Knowing exactly the homogeneous ripening stage reached by the fruits of a given class, a decision about further application with ethylene controlling agents (e.g. 1-MCP) could be taken. The application of 1-MCP aims to prolong shelf-life, reduce disease susceptibility (e.g. scald) and maintain high fruit quality standard. In addition the chemical could extend storage life allowing higher storage temperature regime to be used for all the cold storage period. This could lead to interesting effect on the storage cost reduction, because of the higher temperature regime adopted, and to the environmental sustainability (carried out jointly with UNIPD). Within this context, a mass gene approach by means of an apple microarray set up within WP1 will allow to identify gene sets counterbalancing through 1-MCP the injuring effects of the temperature rise. The most relevant genes will be further characterized by means of RT-PCR and their functions assessed.
WP4b Advanced traceability system.
The specific aim is to create an advanced system of traceability which allows to model the effect of the different variables on the fruit quality to optimize storage and distribution strategy. Starting from the activity carried out in the WP3, the information collected at field level (orchard map, fruit quality and ripening stage- size, skin and ground colour, starch content, etc) will be part of the fruit quality “pedigree” for each bin. These information will be precisely transferred from the field to the grading centre. In addition, the fruit ripening evolution will be continuously followed also in cold storage conditions. To achieve this, a new instrument (DA Fruit logger-DAFL) will be used during the project duration. The DAFL uses the same principle of the DA-Meter and it is practically represented by a belt adjustable to each selected fruit according to its size, which carries a small detector able to record the IAD evolution in cold storage conditions. The DAFL will be positioned on a given number of single fruits maintained in the cold storage room and will measure in real-time the ripening modification occurring during storage. The DAFL will allow also to measure other parameters, such as T and RH, at desired given time, and to transmit these data automatically outside the storage room. All the information acquired (DA-meter, DAFL) will be transferred in real time to a centre system which will keep trace of the fruit batch provenience, and of the fruit quality traits to optimize storage strategy and distribution.
WP4c Comparative methods between objective and perceived quality.
DCA-UNIBO and FEM-IASMA will collaborate in implementing the requirements for defining parameters to compare perceived quality with instrumental quality. The latter, as normally and actually measured with traditional destructive methods (refractometer, penetrometer, etc) is very often a long way from the quality perceived by consumers. This is also because the analyses of traditional fruit quality traits are cheap and fast, but they do not consider other fundamental aspects of quality, such as antioxidant power, aroma volatile emission, soluble sugars and organic acids content (Halbwirth et al. 2009). A more accurate definition of fruit quality would require sophisticated analyses (i.e. HPLC, gas chromatography, mass spectrometry) that are not usually run because they should be carried out only in well equipped laboratories with trained personnel. In any case, simple or more complex destructive analyses can be performed only on samples of a limited number of fruit, often not fully representative of the entire batch. The development of non-destructive techniques for assessing internal fruit quality attributes might solve this problem offering a number of advantages, such as the possibility to extend the assessments on a high number or even on all the fruits, to repeat the analysis on the same samples monitoring their physiological evolution, and to achieve real time information on several fruit quality parameters at the same time. To achieve this, at the point of sale, fruits grouped in classes of homogeneous ripening via the non-destructive devices (vis/NIRs for physical properties and e-nose for VOC’s definition) will be tested by the consumers (carried out in collaboration with CReSO).Consumers will have to express their preference using the descriptors normally used (sweetness, sourness, aroma, etc) as well as others that will be also considered, as for example, apple crunchiness, rather than pulp hardness, that is probably a better parameter for expressing consumers’ satisfaction. Non-destructive methods, such as the DA-meter and the electronic nose, which give an indication of overall fruit quality and function similarly to the human nose, may constitute a link between instrumental quality and perceived quality (Costa et alii, 2008).