2.2.2.1. Sampling on canning chain to evaluate the impact of each step of the process
Green beans sampling along the canning chain was performed at Bonduelle’s factory in Renescure (North of France), on two consecutive days, in August 2010. The process is described in Fig. 2.
Upon arrival at the factory, the green beans were washed in water during 30 s–1 min and trimmed for 20 min–1 h at room temperature. Then, green beans were blanched either by aspersion of water or by immersion into a water bath during 4–8 min. The temperature of the blanching water used was from 85 to 95 °C. Green beans were then quickly cooled by aspersion of water for both blanching modes, during a maximal time of 1 min from 85 to 30 °C. Green beans were put into cans and covering liquid composed of water and sodium chloride was added. The cans of green beans were crimped and sent to sterilisation for 6–15 min at a temperature from 125 to 130 °C depending on the sterilisation mode used. Finally, the cans of green beans were cooled.
The green beans were sampled along the canning chain as follows (except for sample E due to arrival time):
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At their arrival at the factory, the samples were called “Raw material”;
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Before and after the blanching step, the samples were respectively called “Before blanching” and “After blanching”;
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Before adding the covering liquid in cans, the samples were called “Before adding covering liquid” (The layout of the plant was such that only two batches could be sampled at this point);
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The “Final product”, sampled immediately after processing, was separated in green beans and covering liquid by sieving;
2.2.2.2. Sampling to evaluate the variability of folates concentration in raw materials and final products
Green beans sampling for the evaluation of folates variability was performed at Bonduelle’s factory in Renescure (North of France), over two weeks, from the end of August 2010 to the beginning of September 2010. This sampling was performed to evaluate the dispersion of folates concentrations in several raw materials and several final products, according to the cultivars and producers. In a general manner, raw materials and final products were independent, except for two batches for which the final product corresponds to the raw material (cv. Samoa, batches n° 1816 and 1874).