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Abstract(s)
Hazelnut is one of the most popular dried fruit all over the world, because of its unique organoleptic characteristics and also due to its nutritional composition [1]. The characteristics of the different hazelnut varieties that exist worldwide are dependent of several factors, such as, the genotype, agricultural and post-harvest practices, climatic conditions and also the geographical location where they are cultivated. Moreover, hazelnut quality is also affected by its chemical composition [2]. The
aim of this study was to access the microbiological quality and also the chemical composition of three hazelnut varieties (Grada de Viseu, Tonda de Giffoni and Butler), cultivated in the Viseu region, Portugal. Therefore, hazelnut kernels were analysed for moisture, water activity, fat, protein, fibre and ash. Furthermore, there also quantified the microorganisms at 30⁰C and the moulds and yeasts at 25⁰C. All analysis were performed in triplicate. According to the results, fat was the major chemical component for all varieties, varying from 64.38±1.67 g/100 g (var. Grada) to 78.16±1.71 g/100 g (var. Tonda),
with statistically significant differences between the varieties (p<0.0005). Moisture content was higher for the var. Butler
(6.02±0.37 g/100 g) and lowest for the var. Tonda (4.86±0.33 g/100 g), with statistically significant differences between
the three varieties under study (p=0.013). According to the recommendations of the European Union, moisture content of
hazelnut kernels should not exceed 6.0% [3]. As for the water activity, the values ranged from 0.54±0.01 (var. Butler) to
0.56±0.01 (var. Grada), but in this case with no statistically significant differences between the varieties. The var. Butler
presented the fruits with the higher ash content (2.31±0.18 g/100 g), while var. Grada was the one with the lowest value
(1.69±0.16 g/100 g), again with statistically significant differences (p=0.012). The var. Grada presented the higher fibre
(6.13±0.03 g/100 g) and protein content (22.84±0.18 g/100 g), with statistically significant differences among the varieties
in the two cases. The results also showed (Table 1), that according to the limits established for the count of microorganisms
at 30⁰C and mould and yeast by the National Health Institute Doutor Ricardo Jorge [4] (<10 6 CFU/g for microorganisms at
30⁰C, <10 5 CFU/g for yeast and <5x10 2 CFU/g for moulds), all the varieties presented a satisfactory microbiological quality,
with statistically significant differences between the varieties in the case of the quantification of microorganisms at 30⁰C.
Moreover, as it can be observed in Table 1, var. Butler presented the highest values for the microorganisms at 30⁰C and
also for the moulds and yeast at 25⁰C, which may be explained by its higher moisture content. The results of this study are
very important to characterize the microbiological quality and also some chemical properties of the three most representa-
tive hazelnut varieties cultivated in Portugal.
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Pedagogical Context
Citation
Ferrão AC, Guiné R, Silva M, Correia P. (2023) Microbiological and Chemical Composition of Some Portuguese Hazelnuts, in Book of Abstracts of the XXII EuroFoodChem, Belgrado, Sérvia, pp. 228.