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.

Unveiling Apple Diversity: The Quality of Juice Produced from Old vs. Commercial Apple Cultivars

This research is focused on comparing the compositions of juice produced from old and commercially grown apple cultivars. We examined factors such as pH, total acids, soluble dry matter, polyphenol profile, and antioxidant activity, which impact the attributes, safety, shelf life, and nutritional value of the juice. Our analysis revealed differences between these two groups of cultivars. For instance, pH values ranged from 3.04 (in 'Bobovec') to 3.69 (in 'Fuji'). The proportions of acids varied from 0.07 g/100 mL (in 'Fuji') to 0.19 g/100 mL (in 'Wagener'). Soluble dry matter content ranged from 14.10% (in 'Fuji') to 18.50% (in 'Kraljevčica'). We also observed variations in sugar content and composition among cultivars; for example, sucrose levels varied from 16.11 g/L ('Fuji') to 39.36 g/L ('Golden Delicious). Glucose levels ranged from 4.95 g/L ('Jonagold') to 19.18 g/L ('Fuji'), while fructose levels spanned from 50.78 g/L ('Austrougarka') to 427.97 g/L ('Ilzer Rosenapfel'). Furthermore, old apple cultivars exhibited higher concentrations of phenols and flavonoids compared to commercial ones; we also noted significant variations in flavonol levels among different cultivars. The 'Wagener' and 'Božićnica' apple varieties had levels of myricetin measuring 0.53 and 0.52 µg/mL, respectively. On the other hand, 'Bobovec' stood out for its content of procyanidin B2 with a concentration of 422.61 µg/mL. When examining non-flavonoid compounds, it was found that old apple cultivars had higher concentrations of gallic acid, trans-ferulic acid, and chlorogenic acid. However, commercial cultivars showed dominance in caffeic and p-coumaric. Comparisons of antioxidant capacity using DPPH and ABTS assays clearly demonstrated the superiority of old apple cultivars. Overall, this study highlights the importance of utilizing apple cultivars for juice production. Their distinct compositions and higher antioxidant capacities contribute to potential health benefits. Preserving these cultivars for enhanced juice quality and nutritional value is encouraged. Further research could explore cultivation practices' impact on composition and health benefits.

Identification and Quantification of Polyphenols in Croatian Traditional Apple Varieties

Apples and apple-based products are particularly interesting due to being a good source of polyphenols in an everyday diet. Recently there has been increased interest in the preservation of traditional apple varieties due to studies that suggest that traditional apple varieties have a higher content of polyphenols and antioxidant activity compared to commercial varieties. This study shows that traditional apple varieties contain higher concentration of polyphenolic compounds than conventional ones, such as chlorogenic acid (1.29-456 mg/kg dw), catechin (0.70-312 mg/kg dw), epicatechin (1.75-244 mg/kg dw), procyanidin B1 + B2 (4.08-358 mg/kg dw) and quercetin-3-glucoside (0.96-231 mg/kg dw). This research underlies the great potential of traditional apple varieties as a source of natural antioxidants and polyphenolics.

Cocoa Shell as an Innovative Ingredient in Chocolate with a Strong Alcoholic Filling

he chocolate industry is constantly developing new products with different fillings, toppings, flavours, etc. Chocolates with alcoholic filling are popular, especially with young adults. In chocolates with alcoholic filling different kinds of thickeners can be used to increase the viscosity of the filling and make production easier. In this study, we examined cocoa shells, a by-product of the chocolate industry, as a new ingredient and thickener of an alcoholic filling. Chocolates with bitter herbal liqueur were produced in a ball mill with four different fillers. A comparison of guar gum and cocoa shell as thickeners was conducted. The influence of the filling ingredients on the stability of the filled chocolate was determined by measuring colour and gloss over 30 days of accelerated fat bloom. The results showed that chocolates for which the cocoa shell was used were more stable than chocolates where guar gum was used. Evaluation of sensory properties of chocolates with bitter herbal liqueur and different thickeners was conducted by the trained sensory panel. The highest-rated, after sensory assessment, were dark chocolates that contained cocoa shells in the filling. Also, an online questionnaire was conducted to examine consumer preference for a new product. According to the results, it can be concluded that the production of this chocolate would be desirable.

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.

EFFECT OF PROCESSING AND STORAGE ON SAGE (SALVIA OFFICINALIS L.) HONEY QUALITY

The aim of this study was to evaluate the effect of processing (45 °C/48 h and 65 °C/6 h) and two years’ storage on sage (Salvia officinalis L.) honey and to determine the period in which the compliance to the regulations is fulfilled and degradation of nutritive components are minimal. The results showed that processing at higher temperature for shorter period had a greater impact on enzyme activity decrease and increase of color than heating at lower temperature for longer time. Processing had no significant effect on HMF increase, while during storage HMF content increased above maximum prescribed value. Although processing and storage increased phenolic content and antioxidant capacity, at the same time, quality was significantly degraded regarding enzyme activity and HMF content. Therefore, it is recommended to store sage honey for less than two years and if processing is necessary to heat it at as low temperature as possible.

Optimization of MAE for the Separation of Nicotine and Phenolics from Tobacco Waste by Using the Response Surface Methodology Approach

This study intends to valorize by-products of the industrial processing of tobacco to obtain nicotine and phenolics as value-added compounds. Three influential parameters of the microwave-assisted extraction-MAE (temperature, treatment time, and solvent/solid ratio) were studied for the optimization of the extraction protocol for tobacco leaves and three types of waste-scrap, dust, and midrib, respectively. Nicotine was the dominant bioactive compound in all extracts, ranging from 1.512 to 5.480% in leaves, 1.886 to 3.709% in scrap, 2.628 to 4.840% dust, and 0.867 to 1.783% in midrib extracts. Five phenolic compounds were identified and quantified, predominated by chlorogenic acid and rutin. Additionally, total phenol content and antioxidant activity were determined using spectrophotometric assays. Optimization was performed in two aspects: to obtain a maximum extraction yield with minimum nicotine content and to obtain a maximum extraction yield with maximum nicotine content. These findings demonstrate that tobacco waste is a valuable source of bioactive compounds and MAE can be a promising alternative technique to obtain extracts rich in targeted bioactive compounds, especially nicotine.

Bioprospecting of Coralline Red Alga Amphiroa rigida J.V. Lamouroux: Volatiles, Fatty Acids and Pigments

Due to the lack of phytochemical composition data, the major goals of the present study on Amphiroa rigida J.V. Lamouroux were to: (a) investigate and compare volatilome profiles of fresh and air-dried samples obtained by headspace solid-phase microextraction (HS-SPME) and hydrodistillation (HD) followed by gas chromatography and mass spectrometry (GC/MS) analysis; (b) determine fatty acids profile by gas chromatography with flame ionization detector (GC-FID); (c) obtain the pigment profiles of semipurified extracts by high performance liquid chromatography (HPLC) and (d) evaluate the antioxidant and antimicrobial activities of its less polar fractions. The comparison of headspace of fresh (FrAr) and air-dried (DrAr) samples revealed many similarities regarding the presence and abundance of the major (heptadecane and pentadecane) and minor compounds. The hydrodistillate (HD) of DrAr profile was quite different in comparison to HD-FrAr. The predominant compound in HD-FrAr was (E)-phytol. In HD-DrAr, its percentage was approximately one-half reduced, but the abundance of its degradation product phytone and of unsaturated and oxygenated compounds increased indicating more intense fatty acid decomposition and oxidation during drying. The fatty acid determination revealed that the most dominant was palmitic acid (42.86%) followed by eicosapentaenoic acid (19.14%) and stearic acid (11.65%). Among the pigments, A. rigida contained fucoxanthin (0.63 mg g⁻¹ of dry fraction), lutein (5.83 mg g⁻¹), β-carotene (6.18 mg g⁻¹) and chlorophyll a (13.65 mg g⁻¹). The analyzed less polar fractions of A. rigida exhibited antioxidant scavenging activity with diammonium salt of 2,2′-azino-bis (3-ethylbenzthiazolin-6-yl) sulfonic acid (ABTS) assay up to 3.87 mg g⁻¹ trolox equivalents (TE), and with the oxygen radical absorbance capacity (ORAC) assay up to 825.63 μmol g⁻¹ TE (with carotenoids as the major contributors).

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.

Does High Voltage Electrical Discharge Treatment Induce Changes in Tannin and Fiber Properties of Cocoa Shell?

Cocoa shell is a by-product of the chocolate industry that is rich in dietary fiber and bioactive components. In this research, the influence of high voltage electric discharge (HVED) treatment on chemical and physical characteristics of the cocoa shell, i.e., the effects of applied time and frequencies on grinding ability, water binding capacity (WBC), dietary fibers and tannin content was investigated. HVED had a significant influence on the chemical and physical properties of cocoa shell, all of which could be linked to changes in fiber properties. Along with the fiber content, grinding ability and water binding capacity were increased. These properties have already been linked to fiber content and soluble/insoluble fiber ratio. However, this research implies that change in fiber properties could be linked to tannin formation via complexation of other polyphenolic components. Additional research is needed to verify this effect and to establish mechanisms of tannin formation induced by HVED and its influence on fiber quantification.

Physicochemical characteristics of Croatian royal jelly

Due to its high nutritive value, royal jelly usage is increasing, both in human nutrition in native form and as bioactive component in other products (dietary supplements, medicines). The database and regulations on royal jelly characteristics are established in several countries, but not in Croatia. Physicochemical characteristics: moisture, protein content, pH value, total acidity, carbohydrate composition and 10-HDA content in 13 Croatian royal jelly samples were determined with the aim of getting insight to quality of royal jelly produced in Croatia. The obtained results showed that regarding 10-HDA content, one of the most important quality parameter, all samples fulfilled the international standard for royal jelly specifications. Moisture of three samples was higher than prescribed (69.5%, 76.3% and 72.0%, respectively) while one sample had slightly lower protein content than minimum 11% prescribed in international standard. Sucrose content in two royal jelly samples was higher than 3%. Statistically significant correlations were obtained between moisture and protein content, 10-HDA and total acidity as well as between fructose and glucose content. The results of this study will contribute to creation the database of Croatian royal jelly physicochemical characteristics and thus help in setting the royal jelly quality criteria at national level

The Chemistry behind Chocolate Production

Chocolate production is a complex process during which numerous chemical reactions occur. The most important processes, involving most of the reactions important for development of the proper chocolate flavor, are fermentation, drying and roasting of cocoa bean, and chocolate conching. During fermentation, formation of important precursors occurs, which are essential for further chemical reactions in the following processes of chocolate production. Roasting is one of the most important processes due to the occurrence of Maillard's reactions, during which aroma compounds are formed. In this paper, we have reviewed the most important chemical reactions that occur with proteins, carbohydrates, lipids, and polyphenols. Additionally, we present other components that may be naturally present or form during the production process, such as methylxanthines, aldehydes, esters, ketones, pyrazines, acids, and alcohols.

Characterization of Croatian Rape (Brassica sp.) Honey by Pollen Spectrum, Physicochemical Characteristics, and Multielement analysis by ICP-OES

Rape (Brassica sp.) unifloral honey from Croatia was characterized by certain physicochemical parameters, micro- and macroelement content, and pollen spectrum, as determined in 21 honey samples. The Brassica sp. pollen type was predominant in the analyzed samples and ranged between 60 and 98%, with Trifolium spp., Robinia pseudoacacia, Rosaceae, Helianthus annuus, Salix spp., and Taraxacum officinale as the main accompanying pollen types. The electrical conductivity mean value was 0.22 ± 0.05 mS/cm and the glucose/fructose ratio mean value was 1.1 ± 0.07, whereas sucrose was absent in the samples. The most abundant macroelement was potassium (K) (268.49 mg/kg), followed by phosphorus (P) (60.23 mg/kg), calcium (Ca) (54.02 mg/kg), sodium (Na) (22.52 mg/kg), sulfur (S) (15.79 mg/kg), and magnesium (Mg) (12.58 mg/kg). Toxic elements were mainly bellow the LODs; only arsenic (As) concentration was detectable in higher amount (0.233 mg/kg), which may be related to the high arsenic concentration in the soil and groundwater of eastern Croatia. The differences between the two harvesting seasons observed in a large number of elements could be related to climatic and soil conditions and different nectar yields originating from the associated plant species.