Browsing by Author "Smati, Nehed"
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- Bee bread preservation methods: physical, chemical and microbial stability throughout storagePublication . Smati, Nehed; Rodrigues, Paula; Martins, Vitor Manuel RamalheiraBee bread is an important beehive product, and it is growing in commercial interest due to its high nutritional value and richness in bioactive compounds, and it is thus considered as a human functional food. The rich composition of bee bread with different nutrients can result in microbial growth and spoilage, especially when handling practices are not approprite. This work intends to evaluate the impact of different preservation methods - freezing, room temperature, oven drying at 30 °C, and freeze drying - on bee bread physicochemical characteristics and microbial stability, during a storage period of six months. Samples were analysed before the application of the treatments, immediately after the application of the treatments (T0), and after one (T1), three (T3) and six (T6) months of storage. For each time point of analysis, the samples were analyzed for several parameters: microbiological (aerobic mesophiles, lactic acid bacteria, yeasts, moulds, and coliforms), physical-chemical (pH, water activity, moisture content, proteint content, lipid content and ash) and bioactive (total phenolic compounds and antioxidant activity). The techniques of oven-drying and freeze-drying were the most effective in reducing the initial moisture content of bee bread from 16.5% to 9.9% and 11.0%, respectively. These reductions were also evident in bee bread water activity, which was reduced from 0.57 to approximately 0.36, for both preservation techniques. Overall, the various preservation treatments significantly affected the nutritional composition of bee bread. This was particularly evident when room temperature drying was used, causing an increase of 80% on bee bread total lipid content, after a storage period of 3 months. The total phenolic content was also influenced by the preservation treatment applied to bee bread, particularly for freeze-drying, which caused a reduction of approximately 40%, after 1 month of storage, reflected on an increase of 50% for EC50 value, evidencing a decrease in the bee bread antioxidant activity that continued during the whole 6 month storage period. The results obtained for microbial analysis showed that the frozen samples have the highest microbial loads. The preservation at room temperature without previous treatment presented similar or better preservation efficiency compared to oven drying and freeze drying. No significant differences were observed between these treatments in most situations, except for the yeast counts, which the results presented a significant differences between all the treatment througout storage. Overall, each preservation technique acted differently on the various parameters over time. From a chemical perspective, after six months of storage there was no significant difference between treatments. From a microbial point of view, freezing was the least adequate preservation technique, while the remaining preservation techniques showed similar good product stability. Given the results obtained in the present study, preservation at room temperature without any previous treatment seems to be an adequate technique for the preservation of bee bread under the tested conditions. Further studies are required to elucidate the effect of different levels of pH and water activity on the stability of non-treated bee bread.
- Bee bread preservation methods: physico-chemical and microbial stability throughout storagePublication . Smati, Nehed; Aylanc, Volkan; Vilas-Boas, Miguel; Martins, Vitor Manuel Ramalheira; Rodrigues, PaulaBee bread is an important beehive product, with growing commercial interest due to its high nutritional value and to the bioactive compounds it contains, setting it as a good supplement as a functional food. Considering human safety and the significant impact that bee bread is gaining in the field of human nutrition, this work evaluates the effect of distinct preservation techniques on the bee bread physico-chemical and microbiological parameters, throughout a storage period of 3 months.
- Nutritional composition, bioactivity and microbiological stability of bee bread during the preservation processPublication . Aylanc, Volkan; Smati, Nehed; Martins, Vitor Manuel Ramalheira; Falcão, Soraia; Rodrigues, Paula; Vilas-Boas, MiguelBee bread (BB) is a precious beehive product, with growing commercial interest due to its nutritional value and richness in bioactive compounds responsible for its biological activity. In cases where the processing and storage practices of BB are not suitable, significant losses in its nutritional value can occur, becoming vulnerable to microbial growth and spoilage. Here, we aimed to evaluate the effects of different preservation methods (freezing (F), room temperature (RT), oven drying (OD), and freeze-drying (FD) on the physicochemical properties, antioxidant activity, and microbial stability of BB, during a 6-month period. The pH of fresh BB, 3.7, increased with F, OD, and FD preservation methods and reached a maximum of around pH 4.0. Besides, F resulted in the lowest total lipid content loss, 11%, among all the applied methods, followed by FD, OD, and RT with losses of 20%, 24%, and 31%, respectively. The initial protein content of BB, 28%, also decreased over time, for all preservation methods, with losses between 8 to 25%. Moreover, there was a decrease in the total phenolic content of BB with time, which was reflected in the antioxidant activity. Within the microbial parameters, the highest microbial loads were observed using the freezing method. Overall, each preservation technique acted differently on the nutritional, antioxidant activity and microbial stability of BB, nevertheless, considering the results, regular storage at RT seems adequate for this bee product.