Microwave-Assisted Drying for the Conservation of Honeybee Pollen.

Cristina Sgherri,Angelo Canale,Francesca Signorini,Andrea Serra,Antonella Castagna,Matteo Bientinesi,Annamaria Ranieri,Piera Poli,Marcello Mele,Cristiano Nicolella,Giovanni Benelli

doi:10.3390/ma9050363

Cristina Sgherri, Angelo Canale + Show 9 more

Open Access

https://doi.org/10.3390/ma9050363

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Abstract

Bee pollen is becoming an important product thanks to its nutritional properties, including a high content of bioactive compounds such as essential amino acids, antioxidants, and vitamins. Fresh bee pollen has a high water content (15%–30% wt %), thus it is a good substrate for microorganisms. Traditional conservation methods include drying in a hot air chamber and/or freezing. These techniques may significantly affect the pollen organoleptic properties and its content of bioactive compounds. Here, a new conservation method, microwave drying, is introduced and investigated. The method implies irradiating the fresh pollen with microwaves under vacuum, in order to reduce the water content without reaching temperatures capable of thermally deteriorating important bioactive compounds. The method was evaluated by taking into account the nutritional properties after the treatment. The analyzed parameters were phenols, flavonoids, with special reference to rutin content, and amino acids. Results showed that microwave drying offers important advantages for the conservation of bee pollen. Irrespective of microwave power and treatment time, phenol and flavonoid content did not vary over untreated fresh pollen. Similarly, rutin content was unaffected by the microwave drying, suggesting that the microwave-assisted drying could be a powerful technology to preserve bioprotective compounds in fresh pollen.

Highlights

Pollen is an important source of proteins and free amino acids for the diet of honeybees, Apis mellifera L. (Hymenoptera: Apidae)
All analytical results are compared with the untreated pollen sample (UP)
The moisture content is determined through thermogravimetric analysis (TGA)

Summary

Introduction

Pollen is an important source of proteins and free amino acids for the diet of honeybees, Apis mellifera L. (Hymenoptera: Apidae). Pollen is an important source of proteins and free amino acids for the diet of honeybees, Apis mellifera L. Honeybees use pollen as a protein supplement in the diet of the larvae of workers and drones, older than three days old, as well as to feed the adults of the same caste [1]. The commercial production of pollen is carried out by beekeepers, using special traps placed at the entrance of the hives. The threshold for the use of pollen traps is 10%–15% of the total pollen load harvested by bees; from a hive, about 4–5 kg of pollen are obtained within a year [3]

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