# Effects of Drying Methods and Temperatures on the Quality of Chestnut Flows
## 2 Materials and Methods  
### Collection of Chestnut Flour  
The chestnut samples were collected from chestnut plants of the two most widespread cultivars 'Rossolina' and 'Carpinese' within the Metalliferous hills in Tuscany. Fruits were harvested for two consecutive years in October, the optimal period for fruit ripening. In both years, a homogeneous 100 kg lot of fruits provided by \"Associazione Valorizzazione Castagne Alta Maremma\" composed of a 50% weight of \"Rossolina\" and 50% of \"Carpinese\" was selected to represent the mean composition of the crop in the area. The lot was then divided into three sub-samples of 5 kg each. The sub-samples were then dried with three different methods:  
* By the traditional \"metato\" drier, working with a wood fire, covered by ashes, where the fluctuating temperature recorded by a data logger localized into the fruit container ranged from a minimum of 30 \({}^{\circ}\)C to a maximum of 70 \({}^{\circ}\)C, with a mean value of 37 \({}^{\circ}\)C;* By a laboratory oven (Biosec, Tauro, Camisano Vicentino, Italy) at a constant temperature of 70 \({}^{\circ}\)C;
* By a commercial air dessicator (Biosec, Tauro, Camisano Vicentino, Italy) at a steady temperature of 40 \({}^{\circ}\)C.  
The \"metato\" is usually started when it is completely filled with chestnuts, forming a layer of about 50 cm in height which is daily moved by hands. To separate each sample from the mass, the chestnuts were inserted into a large bag made of natural fibers which do not modify the air fluxes through the fruits. This method is also used when a small producer needs to have only its part of chestnuts back. The drying in the \"metato\" took 40 days in year 1 and 35 days in year 2. This was the period the producer's association used for the production of the mass flour to be commercialized.  
The dried chestnuts, resulting from each method, were then manually peeled and sorted to be classified as follows:  
* Non-defective: any color alteration was present neither outside nor inside, with the chestnut appearing totally white;
* Defective: alterations present in 25 \(\pm\) 2% of the volume of the nuts with the flesh turned brown/chalky white.  
The percentage of the alteration was determined by taking a picture of the fruits and measuring the different areas (good and rotted) using the ImageJ program, and then selecting only the chestnuts with about 25% of the external surface interested by a change in color (percentage chosen on the basis of [PERSON] et al. (2022) [25]. This level was chosen because it is easily scorable by manual sorting and it could correspond to the maximum level of defect that a producer could leave in the worst case. It was not possible to use the weight of the rotted and healthy portions because they presented different specific weights. Before the milling, the nuts were manually cut, and we confirmed that a superficial alteration showed the presence also of internal rotting.  
Finally, the dried chestnuts were ground to flour using an electric stone mill (Jumbo model, KoMo Gmbh & Co., Ltd., Hopfgarten, Austria), positioning the selector for the maximum refinement of flour. Summing up, 12 flour samples were obtained according to the different drying methods (3), chestnut state (2), and year of harvest (2).