Search Results (5)

Bee pollen (BP) is a very valuable bee product, and its value depends on its proteins, lipids, amino acids, carbohydrates, vitamins, minerals, and biologically active compounds such as phenolic compounds, which may change depending on the method of pollen preparation after collection and its storage conditions. Therefore, it is very important to determine when the decline in bioactive compounds in BP occurs during storage. The purpose of this study was to evaluate the changes in the content of ascorbic acid and phenolic compounds, and to determine the antioxidant activity of BP extracts depending on their preparation method and storage conditions over a 15-month period, with assessments conducted every 3 months. Dried pollen (at +28 °C on the first day and +35 °C on the second day) and frozen (−20 °C and −80 °C) BP samples were prepared. After 3 months of storage, there was no decrease of ascorbic acid in frozen BP; however, it decreased by 20% in dried BP (p < 0.05). It was determined that in frozen BP, the content of total phenolic compounds decreased by 12–14% (p < 0.05) after 6 months, and in dried BP, it decreased by 7% (p < 0.05) after 3 months. The levels of flavonoids decreased by 10–17% (p < 0.05) in BP after 6 months. Chlorogenic and p-coumaric acids have been observed as the most abundant phenolic acids in BP. During storage (the 6–15-month period), the strongest antiradical and reducing activity in vitro was estimated in the frozen (−80 °C) BP, which was 1.8–3.4-fold and 2.6–3.1-fold higher, respectively, compared to the dried BP extracts. In conclusion, significant results were obtained, showing better stability of phenolic compounds and ascorbic acid during storage in frozen BP compared to dried pollen. Melisopalynological analysis revealed a polyfloral pollen mixture, with Salix spp. and Brassica napus L. predominating in all samples, comprising 34.3% and 36.8%, respectively. Among these, Acer platanoides L., Malus domestica Borkh., and Taraxacum officinale L. were important minor pollens present in the samples examined. Full article

Peach is one of the most common stone fruit crops, but it is also the most thermophilic. One of the main problems in peach cultivation is frost up to −8 °C in spring during pollen development, budding, and flowering. The adaptation of the plant to low temperatures could be related to the activation of the antioxidant system under cold stress. The aim of this work was to test the hypothesis of distinct adaptation mechanisms to cold stress in Prunus persica L. cultivars with various cold tolerances. The difference between this study and the previous ones is that previously, only contrasting varieties (resistant and sensitive) were studied. For the first time, we studied the effect of cold stress on cold-resistant varieties but with different degrees of resistance, such as “Loadel” and “Springold” (medium resistant) and “Podarok Like” and “Temisovskij” (highly resistant). The experiment was designed to simulate the effects of short-term cold snaps, which are a common occurrence during February and March in the south of Crimea. A series of tests were conducted on annual shoots that were frozen at −12 °C. The activity and gene expression of two major antioxidant enzymes, catalase and peroxidase, were studied by spectrophotometry and RT-qPCR, respectively. The experiment showed that these enzymes responded differently to cold stress in varieties with different cold tolerances. Catalase responded similarly in all four varieties. After frost, there was an increase in activity (7-fold in “Temisovskij” and 3-fold in “Podarok Like”) and a decrease in expression. In contrast to catalase, peroxidase showed an opposite response to cold stress in medium-tolerant and highly tolerant cultivars. Peroxidase activity after exposure to low temperatures increased in highly tolerant cultivars (1.5-fold in “Temisovskij”), while it decreased in medium-tolerant cultivars (1.5–2 fold in “Springold” and “Loadel”, respectively). The change in peroxidase expression was the opposite. It decreased in highly resistant varieties and increased in medium-resistant varieties. Thus, our results revealed the opposite response of one of the major antioxidant enzymes (peroxidase) in moderately resistant and highly resistant cultivars. The data obtained show that varieties with a high degree of resistance could have other adaptation mechanisms involved, which may be useful for selecting resistant varieties. Full article

This study investigated the thermal properties of potato and hop pollen for cryopreservation and subsequent cross-breeding. Phase transitions and frozen water content in selected pollen samples were measured using a differential scanning calorimeter (DSC). Unlike hop pollen, potato pollen showed high variability in thermal properties and water content. Three specific types of pollen samples based on their thermal characteristics and water content were distinguished by DSC in potato: (1) ‘glassy’, with a water content lower than 0.21 g water per g dry matter; (2) ‘transient’, with a water content between 0.27 and 0.34 g of water per g of dry matter; (3) ‘frozen’, with a water content higher than 0.34 g of water per g of dry matter. Only the ‘glassy’ pollen samples with a low water content showed suitable properties for its long-term storage using cryopreservation in potato and hops. Cryopreservation of pollen did not significantly reduce its viability, and cryopreserved pollen was successfully used to produce both potato and hop hybrids. The results indicate that cryopreservation is a feasible technique for the preservation and utilization of pollen of these crops in the breeding process. Full article

The bee pollen is a complete and healthy food with important nutritional properties. Usually, bee pollen is consumed dehydrated, but it is possible to market it as fresh frozen pollen, favoring the maintenance of its properties and greatly increasing its palatability, compared to dried pollen. However, fresh frozen pollen maintains a high microbiological load that can include some pathogenic genus to human health. In this work, ozonation combined with drying is applied to reduce the microbiological load. The lowest timing exposure to ozone (30 min) was chosen together with hot-air drying during 15 min to evaluate the shelf-life of treated bee-pollen under cold storage (4 °C), and initial reductions of 3, 1.5, and 1.7 log cycles were obtained for Enterobacteriaceae, mesophilic aerobes, and molds and yeasts counting, respectively. Six weeks after treatment the microbial load was held at a lower level than initially observed in fresh bee-pollen. In addition, ozone treatment did not have a negative impact on the polyphenols evaluated. Likewise, the sensory profile of the bee pollen under different treatments was studied. For all these assays the results have been favorable, so we can say that ozonation of fresh pollen is safe for human consumption, which maintains its polyphenols composition and organoleptically is better valued than dried pollen. Full article

In the cut flower market, traditional breeding is still the best way to achieve new rose cultivars. The geographical delocalization of cultivar constitution (generally made in Europe and North America) and plant cultivation (large areas in Africa and South America) represents a limit point for crossing and selection. Rose breeders often need to overcome geographical distances, resulting in asynchrony in flowering among crossing parents, by storing and sending pollen. Hence, a key aspect in breeding programs is linked to pollen availability and conservation, jointly with the identification of parameters related to pollen fertility. In this study we present the results of three different trials. In the first, pollen diameter and pollen viability were chosen as fertility predictors of 10 Rosa hybrida commercial cultivars. In the second trial, aliquots of dried pollen grains of six R. hybrida cultivar were stored under two different temperatures (freezer at T = −20 °C and deep freezer at T = −80 °C) and after a wide range of conservation period, their viability was measured. In the third trial, the effective fertilization capacity of frozen pollen of 19 pollen donor cultivars was evaluated during 2015 crossing breeding plan, performing 44 hybridizations and correlating the number of seeds and the ratio seeds/crossing, obtained by each cultivar, with in vitro pollen germination ability. Full article