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The presented paper covers the preliminary studies on microwave inactivation of honey enzymes described as diastase number (DN). All the investigations were done on commercially available honey from Polish local market. Microwave processes were compared to the conventional ones. In the case of conventional conditions, the constant rate of diastase enzyme inactivation was estimated using the first order kinetics. In the case of microwave heated samples, it was impossible to establish the rate constant; however, the investigation proved the suitability of such kind of processing for short-term thermal treatment of honey.
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... The process is most often carried out in a water bath at a temperature no higher than 40ºC, for 24-48 hours. However, keeping honey Ultrasounds in honey fixation or decrystallization for several days at 42°C can cause changes as strong as short-term heating (Kowalski et al., 2012). All honey types behave similarly when heated, which causes the loss of the crystalline phase. ...
... Based on the experiment, it can be concluded that the use of ultrasound and microwave for honey decrystallization is fast and safe regarding HMF formation. A few studies have been related to the use of ultrasounds to honey processing but the use of microwave has been less frequent (Thrasyvoulou et al., 1994;Bakier, 2007;Stasiak & Dolatowski, 2007;Kowalski et al., 2012;Subramanian et al., 2017). However, all of these Ultrasounds in honey fixation or decrystallization authors focused on the physical aspects of decrystallization process and honey quality parameters according to legal requirements, including diastase activity. ...
Article
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Crystallization of honey is a natural process occurring during honey storage and forces beekeepers to practice the decrystallization process, which mainly concerns honey heating. The aim of this study was to examine the possible use of ultrasounds or microwave radiation to delay the crystallization of honey and to liquefy crystallized honeys while maintaining their biological activity. Lime, acacia and multifloral honeys obtained from a local apiary were used. Fresh honeys were pretreated through ultrasounds (40 kHz, for 5 and 20 min) or microwaves (800 W, 4 x 30s) in order to obtain samples U5, U20 and M, respectively. Experimental and control samples were stored for twelve months at room temperature (20±2°C) without light. Crystallized honey was liquefied through the same methods of ultrasounds (sample U5* and U20*) and microwaves (sample M*). Naturally crystallized honeys were used as the controls. For fixed (U5, U20 and M) and decrystallized (U5*, U20*, M*) honeys, the water content (refractometrically), antioxidant properties (DPPH method), total phenolics content (Folin-Ciocalteu method) and enzymatic activity (diastase, α-glucosidase, β-galactosidase and α-mannosidase) were determined. The analyzed physicochemical parameters for both fixed and liquefied honeys did not differ significantly (P>0.05) in comparison to the control honey. Moreover, the decrystallization process increased the antioxidant activity of all tested honeys. The smallest changes in honey properties to ultrasonic treatments were observed, and this method was recommended to delay the crystallization process and significantly accelerate the liquefaction time of solid honeys without compromising its quality.
... However, in this study, the DA was lower than 8 DN, indicating excessive thermal processing. Kowalski et al. (2012) reported no DA in honeydew honey after increasing the heating time above 30 min at 90 • C. In the same line, several studies pointed out that prolonged heating at high temperatures causes a high concentration of HMF in honey. For instance, the honey processed at the 75 • C for 24 h presented too high values of the HMF (from 173.4 to 226.35 mg/kg) (Karabournioti & Zervalaki, 2001). ...
... The heating process by microwaves occurs quickly than conventional isothermal heating, and it allows a lower impact on HMF values of the processed honey due to the lower times required to achieve a specific temperature set point. Nevertheless, the HMF formation in honey seems to increase at higher potencies for the same processing time, because it results in higher final temperatures and lower diastase activities (Kowalski, 2013;Kowalski et al., 2012). ...
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Honey is a natural food of worldwide economic importance. Over the last decades, its potential for food, medical, cosmetical, and biotechnological applications has been widely explored. One of the major safety issues regarding such applications is its susceptibility to being contaminated with bacterial and fungi spores, including pathogenic ones, which may impose a hurdle to its consumption in a raw state. Another factor that makes this product particularly challenging relies on its high sugar content, which will lead to the formation of hydroxymethylfurfural (HMF) when heated (due to Maillard reactions). Moreover, honey's bioactivity is known to be affected when it goes through thermal processing due to its unstable and thermolabile components. Therefore, proper food processing methodologies are of utmost importance not only to ensure honey safety but also to provide a high‐quality product with low content of HMF and preserved biological properties. As so, emerging food processing technologies have been employed to improve the safety and quality of raw honey, allowing, for example, to reduce/avoid the exposure time to high processing temperatures, with consequent impact on the formation of HMF. This review aims to gather the literature available regarding the use of conventional and emergent food processing technologies (both thermal and nonthermal food processing technologies) for honey decontamination, preservation/enhancement of honey biological activity, as well as the sensorial attributes.
... The formation of monohydrate glucose crystals of different sizes around the 35 crystallization grains leads to the solidification of honey (Bhandari, D'Arcy, & Kelly, 1999;Bogdanov, 36 Crystallization limits the flow of unprocessed honey out of storage containers (Subramanian,39 Hebbar, & Rastogi, 2017). This creates a handling and processing uncertainties for the honey handlers 40 and processors as they do not have the slightest impact on how his product will look after several 41 months of storage (Kowalski, Łukasiewicz, Bednarz & Panus, 2012;Subramanian, Hebbar, & 42 Rastogi, 2017). Additionally, the top liquid layer in a container of a crystallized honey will contain 43 more water than the bottom crystallized portion which makes the top liquid layer vulnerable to yeast 44 growth and fermentation (Bhandari, D'Arcy, & Kelly, 1999). ...
... Additionally, the top liquid layer in a container of a crystallized honey will contain 43 more water than the bottom crystallized portion which makes the top liquid layer vulnerable to yeast 44 growth and fermentation (Bhandari, D'Arcy, & Kelly, 1999). Moreover, the consumers prefer liquid 45 honey, easier to dispense (Kowalski, Łukasiewicz, Bednarz & Panus, 2012;Bogdanov, 2016). 46 ...
Article
The aim of the research was to assess the impact of liquefying honey by ultrasound processing on its biological activity. Four solid honey samples of different botanical origin were decrystallized by using the ultrasound (sonic bath, 40 kHz, 800 W) and conventional thermal processing (water bath, 40 °C). The biological properties of liquefied and control solid honeys were compared. The ultrasound processing significantly shortened the time of honey liquefaction (from 24 h to 15 min) and delayed of the re-crystallization process compared to conventional method (from 1 to 4 months). Diastase number was comparable in ultrasound and unprocessed honeys, but decreased in conventionally liquefied samples (by 8 to 20.6%) whereas the activity of α-mannosidase and β-galactosidase was insignificantly affected only. Growth inhibition of S. aureus and E.coli by 12.5% water solution of control honey samples was variety-dependent, the lowest for rape (12 and 19%) and the highest for honeydew (32 and 38%, respectively). No significant changes were observed after ultrasound treatment. The antioxidant properties of ultrasound processed honeys were insignificantly reduced up to 8%, while total polyphenols content increased by 3–6% in 75% of tested samples. The hydroxymethylfurfural (HMF) content significantly increased after both treatments (from 31 to 40%), however without exceeding the allowable limit. Industrial relevance Honey crystallization during storage is natural but undesirable serious problem in processing and marketing of the honey. The ultrasound processing shortened the processing time (saved costs), limited the honey biological activity deterioration, and delayed the re-crystallization of processed honeys. Ultrasound processing is a beneficial non-thermal alternative for conventional liquefying of honey by heating.
... This showed that comb and processed honey can essentially be differentiated based on enzyme patterns that projected towards the comb honey; and antioxidants associated with processed honey. According to Kowalsk et al. (2012), comb honey had a relatively higher amount of enzymes, and the processing of honey possibly reduced the level of enzymes. Contrarily, the processing of honey is used to increase the antioxidant activity of honey, which is generated from the Maillard and caramelization reactions (Turkmen et al., 2005). ...
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In this study, comb and industrially processed honey samples collected from Bonga forest were investigated in relation to Melissopalynology and enzyme content, antioxidant and physicochemical properties. Melissopalynology categorized honey samples as Croton macrostachyus and Schefflera abyssinica honey. The physicochemical properties of the honey were determined using the Association of Official Analytical Chemists (AOAC) and International Honey Commission (IHC) methods. The enzymatic and antioxidant properties of honey were evaluated using the spectrophotometric method. The highest enzyme activity was observed in Croton macrostachyus comb honey (diastase=7.44±0.13°Schade and invertase=13.97±0.2 Invertase number (IN). Croton macrostachyus processed honey exhibited the highest values in flavonoids (83.36±1.65 mg Catechin equivalents (CEQ)/100g)), Ferric reducing antioxidant power (FRAP) (69.94±1.0 mg Ascorbic acid equivalents (AAE)/100g), and Inhibitory Concentration (IC50) (136.3±0.00 mg/ml), while Schefflera abyssinica comb honey had stronger 1,1-diphenyl-2-picrylhydrazyl radical scavenging (DPPH) (49.47±0.00%) activity. The principal component analysis revealed that enzymes can be associated with comb honey, and antioxidants with processed honey. Thus, comb and processed honey can be differentiated based on the enzyme level, and Croton macrostachyus and Schefflera abyssinica honey can be identified using pollen analysis.
... Furthermore, Singh et al. [5] set a desiccant honey dehydrator that heats and dehumidifies air to reduce honey's moisture content using a silica gel desiccant bed. While studies on microwave-based honey moisture reduction, such as Cui et al. and Kowalski et al. [6,7], have been investigated microwave vacuum as a capability approach for obtaining high-quality dried honey. Few studies are using the drying method and comparing it with other honey moisture reduction. ...
Article
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Honey is thermally heated at various methods to decrease the moisture content and prolong the shelf life. The heating methods might decrease the quality of honey's physicochemical and biochemical properties. The present study thermally treated the honey with a pasteurizer, evaporator, and dehumidifier. The most thermally affected to decrease the moisture content were treatment by dehumidifier (14.09%), subsequent evaporation (8.41%), and pasteurization (8.41%). After heating, significant differentiation was also observed in the variation of both HMF (Hydroxymethylfurfural) content and diastase activity according to the botanical origin of the honey sample. In line with the biochemical analysis of honey, total phenolic decreased significantly during the pasteurization treatment. Evaporation was the most resistant thermal treatment due to its ability to maintain the level of HMF and the enzyme diastase as a standard for honey quality. However, changes made in physicochemical and biochemical quality are still in compliance with national and international legal limits.
... The enzymatic activity of diastase, expressed as diastase number (DN), is another legislative indicator of honey quality. Several studies found that conventional heating of honey at 90 • C for 20 or 30 min did not cause excessive changes in the diastase activity and thus did not significantly affect its quality (Kowalski, Lukasiewicz, Bednarz, & Panus, 2012;Tosi, Martinet, Ortega, Lucero, & Re, 2008). Similarly, thermal treatment of stingless bee honey samples at 90-95 • C for 15 and 60 s did not change the values of most physico-chemical parameters including HMF and DN values (Braghini et al., 2019). ...
Article
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