Analysis of δ13C and δ15N values in Croatian honey by EA-IRMS and possibility of their application in botanical origin verification.

The aim of this work was to give characteristic stable carbon and nitrogen isotope ratio (δ13Choney, δ13Cprotein and δ15N) ranges and examine their relation with botanical origin of honey. Despite that δ13C parameter has primary purpose to detect honey adulteration, stable isotopes generally have become important parameter for detection its botanical and geographical origin. The data about stable isotopes are scarce in comparison to other well-known parameters in honey, and in Croatia there is no data about stable isotopes in unifloral honey. This research includes six characteristic honey types (black locust, chestnut, lime, rape, winter savory, and sage honey) from Croatia. Large number of differences between honey types were found in the analyzed IRMS parameters. PCA analysis has successfully separated winter savory from all other honey types, except sage honey, whose samples differed from black locust samples. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-023-05888-9.

Characterization of Rare Himalayan Balsam (Impatiens glandulifera Royle) Honey from Croatia.

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.

Production of biodiesel by Burkholderia cepacia lipase as a function of process parameters.

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.

Screening of Six Medicinal Plant Extracts Obtained by Two Conventional Methods and Supercritical CO2 Extraction Targeted on Coumarin Content, 2,2-Diphenyl-1-picrylhydrazyl Radical Scavenging Capacity and Total Phenols Content.

Six medicinal plants Helichrysum italicum (Roth) G. Don, Angelica archangelica L., Lavandula officinalis L., Salvia officinalis L., Melilotus officinalis L., and Ruta graveolens 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 M. officinalis EtOH extracts, but its SC-CO2 extraction yield was very low for further investigation. Coumarin was also found in SC-CO2 extracts of S. officinalis, R. graveolens, A. archangelica, and L. officinalis. EtOH extracts of all plants exhibited the highest DPPH scavenging capacity. SC-CO2 extracts exhibited antiradical capacity similar to hexane extracts, while S. officinalis 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 H. italicum) 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.