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Hydroxycinnamic acids are a major group of phenolic compounds widely distributed in plants. Among them, chlorogenic acids and caffeic acid have been in the focus of interest due to their impact on food quality and their putative health benefits. Numerous microorganisms like lactic acid bacteria are able to hydrolyze chlorogenic acids by cinnamoyl esterase enzymes. Data on the specificity of theses enzymes regarding the cleavage of distinct isomers of mono- or dichlorogenic acids is lacking. Lactobacillus reuteri, Lactobacillus helveticus, and Lactobacillus fermentum were screened for their ability to hydrolyze chlorogenic acid isomers in culture medium. Concentrations of chlorogenic acids and the released caffeic acid were determined by UHPLC-ESI-MS. The highest hydrolysis rate (100%) was observed for the hydrolysis of 5-CQA by Lactobacillus helveticus. A so far unknown metabolic pathway for the cleavage of 4-CQA is proposed including isomerization to 5-CQA and 3-CQA followed by hydrolysis.

The iridoid profile of four Vaccinium species was investigated using UHPLC-MS to obtain further information about this group of species for phytochemical characterization. Fruits of bog bilberry (Vaccinium uliginosum L.) showed 14 different iridoid glycosides with a total amount of 20mg/kg fresh weight (FW), whereas bilberry (Vaccinium myrtillus L.) contained 11 iridoid glycosides and a total amount of 127mg/kg FW. Highbush blueberry (Vaccinium corymbosum L.) and lowbush blueberry (Vaccinium angustifolium L.) contained none of the investigated iridoid glycosides. Among the different iridoids, the isomers scandoside and deacetylasperulosidic acid as well as a dihydro derivative thereof were described for the first time in the Ericaceae family. The p-coumaroyl isomers of scandoside, deacetylasperulosidic acid and dihydromonotropein are reported for the first time in V. myrtillus and V. uliginosum. Monotropein and its p-coumaroyl isomers were found for the first time in V. uliginosum. The comparison of iridoid profiles in bilberry fruit and juice samples revealed constant proportions throughout the juice processing. Quantification and profile determination of iridoids may be used for species differentiation and thus for authentication purposes.

Alk(en)ylresorcinols (AR), a class of phenolic lipids, are regarded as antifungal compounds showing high potential for the use in plant protection, especially against Fusarium head blight (FHB). In view of the very limited knowledge of the activity of single AR against Fusarium species, the antifungal effect of crude extracts, fractions and isolated homologues from wheat and rye bran was determined. It was shown that the saturated AR are the active compounds in the extracts, whereas the presence of unsaturated molecules leads to an antagonistic effect. The activity of single saturated AR is dependent on the chain length, but for highest antifungal efficiency a mixture of saturated homologues is required. Affecting the stage of germination, these molecules reduce, and may even completely prevent, the growth of the tested Fusarium species.

A sensitive and fast analytical method has been developed and validated for the simultaneous identification and quantification of nine fat soluble vitamins and their derivatives (retinol, retinyl acetate, retinyl palmitate, cholecalciferol (D3), α-, β-, γ-, and δ-tocopherol, α-tocopheryl acetate) along with three carotenoids (β-carotene, lutein and zeaxanthin) in dietary supplements and infant formulas using a fast liquid chromatography (UFLC) system coupled with tandem mass spectrometry. Separation was performed within 15 min on a YMC C 30 column (100 mm × 2 mm I.D., 3 μm) using methanol:water (90:10 v/v) and tert -butyl methyl ether (TBME):methanol (80:20 v/v) as the mobile phase with gradient elution. Quantification was carried out by multiple reaction monitoring in combination with information dependent acquisition (IDA) using atmospheric pressure chemical ionization (APCI) in the positive mode. Enhanced product ion scan was used and the mass spectrum of each target compound confirmed their presence in the analyzed extracts. Extraction recovery for all analytes spiked at two levels ranged from 90% to 105%. The overall intra-day precision values for the method based on the relative standard deviation for three QC levels were below 6% for all analytes. The accuracy ranged from 87.6% to 113.5%. A selection of multivitamin supplements and infant formulas available on the Canadian market was analyzed and the results showed good agreement with the values declared on the labels.

Three different commercial enzyme preparations were evaluated with respect to the extractability and chilled storage (10 °C, 9 days) stability of bilberry skin anthocyanins in model systems. Using ultra high-performance liquid chromatography–diode array detection, 15 individual anthocyanins were characterized, with delphinidin and cyanidin glycosides being the predominant compounds. Except for the galactosides of cyanidin and peonidin, 1.2–4.7 times higher concentrations of individual anthocyanins were observed for the extracts from enzymatically treated bilberry skin suspensions. Anthocyanin degradation followed well (R2 = 0.89–0.98) a first-order reaction kinetics and the half-life values increased (12–64%) due to enzyme-assisted extraction. The results obtained demonstrate an improved storage stability of anthocyanins, enzymatically released from the bilberry skin matrix. On the basis of the enzyme screening assay, a novel process, composed of partial dejuicing (pressing, ~ 40% juice yield) of the bilberry mash followed by enzymatic maceration (EMPD), was developed. Interestingly, enzymatic treatment resulted in a decrease among counts of mesophilic and psychrotrophic microorganisms and moulds and yeasts in the bilberry juice upon chilled storage (10 °C, 9 days), implying an inhibition of the microbial growth. Therefore, applying the EMPD process, this two-step juice extraction technology may be very helpful, allowing both enhanced contents of bioactive compounds and extended microbiological shelf-life of “fresh-like” berry juices.

Potato processing generates potato peels as byproducts. Methanolic extracts from the peels result in mixtures of phenolic acids and glycoalkaloids. Phenolic acids have potential for food applications owing to their antioxidant and antibacterial properties. However, when extracted from potatoes, their separation from toxic glycoalkaloids is needed prior to their applications in foods. Moreover, glycoalkaloids may be used as feedstock for synthesis of pharmaceuticals. This study aimed to develop a method for the extraction and fractionation of phenolic acids and glycoalkaloids from potato peels using food grade water/ethanol-based solvents. Samples were analyzed by ultrafast liquid chromatography (UFLC) and/or ultrafast liquid chromatography–mass spectrometry (UFLC–MS). A methanol-based solvent for extraction was used as a control to be compared with two aqueous ethanolic solvents acidified with acetic acid. The recovery of the predominant compounds from potato peels was comparable for all three solvents. Extraction yielded per 100 g of potato peel fresh weight 17.0 mg α-chaconine, 7.1 mg α-solanine, 0.1 mg solanidine, 4.8 mg caffeic acid, 13.3 mg neochlorogenic acid, and 77.6 mg chlorogenic acid. More than 90% of these compounds were recovered after two consecutive extractions. The crude extract was fractionated by solid-phase extraction at pH 7 and eluted with aqueous ethanol. Quantitative recovery of the phenolic acids and glycoalkaloids was achieved in their corresponding fractions. Hydrolysis followed by solid-phase fractionation of the crude extract allowed recovery of 139 μmol caffeic acid/100 g potato peel fresh weight. Partial degradation of caffeic acid and glycoalkaloids occurred during the process. Degradation of caffeic acid can be likely mitigated by the addition of antioxidants and metal chelators. The method developed in this study allows the sustainable recovery of secondary plant metabolites from potato peels and their fractionation using food grade water/ethanolic solvents for application of phenolic extracts free of toxic glycoalkaloids for food preservation, and of glycoalkaloid extracts for synthesis of pharmaceuticals.

Phenolic acids and flavonol O-glycosides were extracted from the peels of jocote fruits (Spondias purpureaL.,Anacardiaceae) harvested in Costa Rica and characterized using ultra high-performance liquid chromatog-raphy coupled with diode array and electrospray ionization mass spectrometric detection (UHPLC–DAD–ESI-MSn). The analytical system allowed the separation of 21 phenolic compounds within less than 20 min. Their characterization was based on retention time, UV spectra and MS fragmentation pattern, and the comparison with reference substances, if available. In addition to phenolic acids, several O-glycosides of quercetin, kaempferol, kaempferide and rhamnetin were detected. This is the first study on the phenolic composition of jocote, highlighting the importance of tropical fruits as a source of natural antioxidants. UCR::Vicerrectoría de Docencia::Ciencias Agroalimentarias::Facultad de Ciencias Agroalimentarias::Escuela de Tecnología de Alimentos UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Centro para Investigaciones en Granos y Semillas (CIGRAS)

Mango ( Mangifera indica L.) kernels were successively extracted with hexane and methanol and the effects of extraction on the profile of gallotannins as well as on their antimicrobial activity and iron-binding capacity were determined. A new method based on fast liquid chromatography with diode array and mass spectrometric detection was developed which allowed the separation of gallotannins in less than 7 min. Gallotannins remained stable during Soxhlet extraction with hexane. Methanolysis led to the degradation of highly galloylated tannins to yield penta- O -galloylglucose and methyl gallate. The antimicrobial activity of the extracts was not affected by the compositional change, whereas the iron binding capacity increased with increasing amounts of methyl gallate. The less complex profile of antimicrobial compounds obtained after methanolysis compared to the crude extract will facilitate the standardization of extracts and their application in target products.