Despite the already established route of chemically catalyzed transesterification reaction in biodiesel production, due to some of its shortcomings, biocatalysts such as lipases present a vital ...alternative. Namely, it was noticed that one of the key shortcomings for the optimization of the enzyme catalyzed biodiesel synthesis process is the information on the lipase activity in the reaction mixture. In addition to making optimization difficult, it also makes it impossible to compare the results of the independent research. This article shows how lipase intended for use in biodiesel synthesis can be easily and accurately characterized and what is the enzyme concentration that enables achievement of the desired level of fatty acid methyl esters (FAME) in the final product mixture. Therefore, this study investigated the effect of two different activity loads of Burkholderia cepacia lipase on the biodiesel synthesis varying the pH and temperature optimal for lipase activity. The optimal lipase pH and temperature were determined by two different enzyme assays: spectrophotometric and titrimetric. The B. cepacia lipase pH optimum differentiated between assays, while the lipase optimally hydrolyzed substrates at 50°C. The analysis of FAME during 24 hr of biodiesel synthesis, at two different enzyme concentrations, pH 7, 8, and 10, and using two different buffers, revealed that the transesterification reaction at optimal pH, 1 hr reaction time and lipase activity load of 250 U per gram of reaction mixture was sufficient to produce more than 99% FAME.
The aim of this study was to evaluate the influence of botanical origin on the fatty acids composition of bee pollen and its nutritional value. The seven monofloral bee pollen samples from different ...locations of Croatia were analysed. A total of 26 fatty acids (from C12 to C24) were identified with a significant difference in their shares in the samples, and nine of them were common to all samples. Assessing bee pollen fatty acids composition through the nutritional quality indicators (high unsaturated fatty acids/saturated fatty acids ratios, high n-3/n-6 and α-linolenic acid/linoleic acid ratios, very low atherogenic and thrombogenic indexes) it is evident that all analysed bee pollen samples are valuable products, which included in the diet can improve the fatty acids balance and could have a positive impact on human health.
Pollen grains are located on the anthers of the flowers, bees collect them and mix them with secretions from their salivary glands and nectar and carry them to the hives in the baskets situated on ...their hind legs. According to the chemical composition, bee pollen is a mixture of proteins, fats, carbohydrates, vitamins and other useful substances for the development of bees in the hive. Due to its nutritional value and potential healthful properties, it is valuable product for beekeeper’s income. The aim of this research was to evaluate the physicochemical characteristics of bee pollen in relation to the period of collection and geographical origin from different localities in Virovitica-Podravina County. Eleven bee pollen samples were collected from stationary apiaries in the period of April and May 2022.Palynological analysis showed that dominated pollen in five samples was pollen from Brassica sp.; Malus spp. and Salix spp. pollen dominate in two bee pollen samples while two samples had dominating pollen coming from Asteraceae family. Physicochemical analysis showed that pollen collected in the period of April had a lower proportion of ash, total fat and phenols, but a higher proportion of moisture content, proteins and carbohydrates.
Six medicinal plants
(Roth) G. Don,
L.,
L.,
L.,
L., and
L. were used. The aim of the study was to compare their extracts obtained by Soxhlet (hexane) extraction, maceration with ethanol (EtOH), and ...supercritical CO₂ extraction (SC-CO₂) targeted on coumarin content (by high performance liquid chromatography with ultraviolet detection, HPLC-UV), 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) scavenging capacity, and total phenols (TPs) content (by Folin-Ciocalteu assay). The highest extraction yields were obtained by EtOH, followed by hexane and SC-CO₂. The highest coumarin content (316.37 mg/100 g) was found in
EtOH extracts, but its SC-CO₂ extraction yield was very low for further investigation. Coumarin was also found in SC-CO₂ extracts of
,
,
, and
. EtOH extracts of all plants exhibited the highest DPPH scavenging capacity. SC-CO₂ extracts exhibited antiradical capacity similar to hexane extracts, while
SC-CO₂ extracts were the most potent (95.7%). EtOH extracts contained the most TPs (up to 132.1 mg gallic acid equivalents (GAE)/g from
) in comparison to hexane or SC-CO₂ extracts. TPs content was highly correlated to the DPPH scavenging capacity of the extracts. The results indicate that for comprehensive screening of different medicinal plants, various extraction techniques should be used in order to get a better insight into their components content or antiradical capacity.
Ability of black locust (n = 7), chestnut (n = 3), lime (n = 5), mint (n = 3), and
honeydew (n = 12) honeys to produce hydrogen peroxide upon dilution, as
well as their glucose oxidase activity were ...investigated in the present study.
The glucose oxidase (GOX) activity was determined by the standard
horseradish peroxidase/o-dianisidin method, while hydrogen peroxide
concentration in honey solutions of five different mass to volume ratios
(1:1; 1:2; 1:4; 1:8; 1:16) by semi-quantitative method using MQuant™
peroxide test strips. The obtained results showed that chestnut, lime,
honeydew and mint honeys exhibited high GOX activity (341.26 ± 128.78,
350.16 ± 124.91, 376.82 ± 69.02, 402.47 ± 60.99 µg H2O2/h g), while black
locust honeys much lower GOX activity of 25.58 ± 21.87 µg H2O2/h g.
The accumulation of hydrogen peroxide in serially diluted honeys has
shown asymmetrical inverted U-shaped curve, where the increase in
hydrogen peroxide accumulation with dilution reached a maximum point,
after which its concentration rapidly declined. Hydrogen peroxide content in
honey solutions of different mass to volume ratio varied from 0 to
294.1 µmol/L h. Lime and chestnut honeys generated the highest
hydrogen peroxide content (264.71 ± 65.77, 245.10 ± 84.90 µmol/L h) on
average, while black locust, mint and honeydew honeys at least two-fold
lower amounts (113.40 ± 50.84, 127.45 ± 33.96, 112.75 ± 98.42 µmol/L h).
Lack of correlation between glucose oxidase activity and hydrogen peroxide
content indicates that the glucose oxidase activity does not present a reliable
parameter for the prediction of hydrogen peroxide content produced in honey
solutions.
Himalayan balsam (Impatiens glandulifera Royle) is an invasive garden ornamental plant species originating from Asia, which produces significant amounts of nectar. In Croatia, it is widely ...distributed along the banks of the Mura River. Although this plant species is widespread in Europe, there are still no available scientific data about this unifloral honey type. The results showed that Himalayan balsam honey is characterized by the high presence of pollen grains in the pollen spectrum (59−85%), natural higher diastase activity (39.1 ± 7.98 DN), negative specific rotation (−21.2° ± 6.89) and an extra light amber color (48.5 ± 12.69 mm Pfund). The carbohydrate profile is characterized by monosaccharides fructose (39.34 ± 0.65 g/100 g) and glucose (31.91 ± 1.42 g/100 g) with a ratio >1.23, while the most commonly represented disaccharide was maltose (3.04 ± 0.79 g/100 g). The average total phenolic content was 130.97 ± 11.17 mg gallic acid/kg honey, and the average antioxidant capacity value was 225.38 ± 29.58 µM Fe(II). The major mineral element was K, with an average of 533.92 ± 139.70 mg/kg. The sensory profile was characteristic with a light orange color and medium-intensity odor and aroma. The crystallization rate was moderate and characterized by the appearance of opalescence and gelatinous forms of crystals. The results of this study provide the first insight into the melissopalynological, physico-chemical and sensory profile of Himalayan balsam honey.
The positive effects of honey bee venom on human health and the high market price are the main reasons for beekeepers' increasing interest in its production. However, until today there is no ...standardized technology for honey bee venom collection. Today's methods are mainly based on collectors placed at the hive entrance. The main problems with this method are the application of the collector, and the contamination that collected venom may contain which consequently reduces its quality. The disadvantages of this technology can at least partially be eliminated by the use of collectors placed inside the hive. Therefore, this study aimed to evaluate the effect of the collection method on the honey bee venom quality and quantity. The results of the study showed that significantly higher amounts of venom could be collected with collectors within the hive, while at the same time the quality of the venom, considering the melittin content, remained equal. Having in mind that honey bee venom collection has not had a significant impact on strength of the colonies (in comparison to control colonies that were not subjected to venom collection), collection technology with collectors placed inside the hive is a better option.
Although health-promoting properties of royal jelly are known for many years, the absence of quality standards and methods prescribed for their determination leads to royal jelly adulteration. Royal ...jelly is a source of unique unsaturated fatty acid, (2E)-10-hydroxydec-2-enoic acid (10-HDA), and its content is considered as one of the freshness and authenticity parameter. In this study, high performance liquid chromatographic method (HPLC) with UV detection was validated and 10-HDA content in fresh royal jelly samples produced in Eastern Croatia was determined. The data about Croatian royal jelly are not available, therefore the results presented in this study could be considered as pioneer results for Croatian royal jelly characterization in respect of the 10-HDA. Method performance characteristics showed that the used method is fit for purpose. The content of 10-HDA in analysed samples varied from 1.56% up to 3.78%. According to the international recommendations for royal jelly quality, samples were fresh and authentic regarding 10-HDA content. Furthermore, the effect of packaging material on 10-HDA content was observed. Based on the obtained results, the conclusion was reached that if the samples were collected at the same time and frozen after collection, collection and storage of fresh royal jelly in glass and plastic containers had no effect on 10-HDA content.
One of the major challenges in sustainable waste management in the agri-food industry following the "zero waste" model is the application of the circular economy strategy, including the development ...of innovative waste utilization techniques. The conversion of agri-food waste into carriers for the immobilization of enzymes is one such technique. Replacing chemical catalysts with immobilized enzymes (i.e., immobilized/heterogeneous biocatalysts) could help reduce the energy efficiency and environmental sustainability problems of existing chemically catalysed processes. On the other hand, the economics of the process strongly depend on the price of the immobilized enzyme. The conversion of agricultural and food wastes into low-cost enzyme carriers could lead to the development of immobilized enzymes with desirable operating characteristics and subsequently lower the price of immobilized enzymes for use in biocatalytic production. In this context, this review provides insight into the possibilities of reusing food industry wastes, namely, eggshells, coffee grounds, and brown onion skins, as carriers for lipase immobilization.
The present study investigated the possibility of spent coffee ground (SCG) transformation to a cellulose-based enzyme immobilization carrier using a multistep extraction procedure. In the first ...step, SCGs were extracted with n-hexane by Soxhlet extraction in order to obtain SCG oil, while the remaining solid residue was subjected to continuous solvent flow sequential subcritical extraction with 96% and 50% ethanol and water. Afterwards, the obtained solid residue was subjected to alkaline liquefaction with 8% NaOH in order to remove lignin and produce cellulose-enriched SCGs as a potential enzyme immobilization carrier. Multistep extraction transformation of SCGs was monitored by chemical analysis of extracts and obtained solid residues. Soxhlet extraction of 100 g of SCGs yielded 10.58 g of SCG oil rich in linoleic and palmitic acid, while continuous solvent flow sequential subcritical extraction of 100 g of defatted SCGs yielded a total of 1.63 g of proteins, 5.58 g of sugars, 204 mg of caffeine, 76 mg of chlorogenic acid, and 11.97 mg of 5-(hydroxymethyl)furfural. Alkaline liquefaction of 100 g of sequentially extracted defatted SCGs by 8% NaOH yielded 7.45 g of proteins, 8.63 g of total polyphenols, 50.73 g of sugars, and 20.83 g of cellulose-enriched SCGs. Based on the characteristics of cellulose-enriched SCGs including a volume-weighted mean particle size of 277 μm, relative narrow particle size distribution with a span value of 1.484, water holding capacity of 7.55 mL/g, and a lack of carrier leakage, it could be safely concluded that produced cellulose-enriched SCGs fulfills criteria to be used as potential enzyme immobilization carrier. Overall, it seems that the proposed multistep extraction transformation of SCGs has great potential to be used for the production of several high-value added products.
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