PACKAGING AND STORAGE

After drying, hazelnuts are kept in bulk, big bags or silos, waiting for following processing. The prolonged farm storage is strongly discouraged, since the buildings available in the farm are affected by external temperature and moisture conditions, which are not always optimal for maintaining the quality of the hazelnuts. On the contrary, when hazelnuts are delivered immediately after harvesting to processing centers, they are promptly dried and stored in proper conditions allowing the crop to preserve its characteristics for a longer time.

Types of packaging 4.1.

- Small bags: they need to allow crop ventilation and facilitate handling, transport and storage

- Big-bags are bags with very large volumes (500-1.000 kg) generally composed of simple plastic material or by overlapping several layers of different material (e.g. polyethylene, nylon and aluminum). They represent the best way to store hazelnut since it ensures excellent insulation from the external environment. Big bags can be directly and automatically filled with a specific system (Fig.4.1) immediately after the cleaning and drying process.

Hazelnuts are characterized by a low residual moisture content and very weak respiratory activity at room temperature. Despite this, the presence of oxygen is the factor that most reduces the quality of hazelnuts during storage: hazelnuts kept in contact with the air undergo chemical and organoleptic deterioration, regardless of the temperature. However, enzymatic and chemical rancidification processes, and vitamin E degradation, are considerably retarded at low temperature. Mold and insect activity is virtually eliminated near freezing temperatures. In-shell hazelnuts have to be stored in clean and ventilated warehouse (no T controlled) with relative humidity around 65%-70% for max. 90 days (Fig. 4.2).

Preferably, storage has to be performed in containers or big bags allowing the air ventilation, useful for keeping the levels of temperature and humidity homogeneous. Hazelnuts are subject to absorbing smells of the environment in which they are stored, therefore storage in a clean environment free of extraneous odors and in the absence of other fruit and vegetables. Hazelnuts are also very sensitive to damage from ammonia so that even low concentrations (5-10 ppm) can cause blackening.

- Metal mesh containers are generally used for temporary storage of nuts before subsequent processing keeping the product clean and off the ground (Fig. 4.4); these containers allow good air circulation, can be easily stored stacked and are easy to move. They are successfully used in small companies that manage a limited amount of product.

Big bags or other bags:

• Keep in a dry area with good air circulation avoiding plastic bags

• Keep the bags raised from the soil

• All the bags have to be labelled with proper information.

Hopper silos: are very big containers to store big quantities of products designed to store seeds keeping the product off the ground to prevent moisture and reduce the possibility of breakage. They are realized in steel and built in series (Fig. 4.3), then available only for big companies or big nut processing facilities.

After the storage, the lots properly labelled and packed are delivered to the Ferrero plants for further processing (Fig. 4.5)

4.2.2. Nuts storage in processing facility

The optimal storage conditions are a combination of low temperature and percentage of relative humidity less than 70%. The suggested time of storage of in-shell hazelnuts in normal atmosphere condition is (Table 4.1):

- 3-4 months at 3-5 °C and at RH of 50-70%

- 5-6 months at 1-2 °C and at RH of 50-70%.

Better storage conditions may be provided by a combination of low temperature and modified atmosphere (saturated with N2 and/or CO2). It was demonstrated that the use of high concentration of nitrogen (98–100%) in combination with low temperature (4 °C) are the best solution for maintaining unchanged color, firmness, acidity and peroxide values of the kernels. In modified atmosphere cells (Oxygen <1%; Carbon dioxide 0-0.3%; N2 about 99%) with 55-60 % RH and a temperature of 2-4 °C, shelled hazelnuts can be stored for 13-14 months.