Kemal Sarioglu

Effects of certain polyphenols and extracts on furans and acrylamide formation in model system, and total furans during storage.

Using a glucose-glycine and asparagine-fructose system as a Maillard reaction model, the effects of seven polyphenols and solid phase extracts of three plants on the formation of furans and acrylamide were investigated. The polyphenols and extracts were used in biscuit formulation and acrylamide formation was observed. They were used for the storage of the glycine-glucose model system at three different temperatures. The addition of some of the extracts and polyphenols significantly decreased furan formation to different extents. All phenolic compounds and plant extracts decreased in the range of 30.8-85% in the model system except for oleuropein, and all of them decreased in the range of 10.3-19.2% in biscuit. Total furan formation was inhibited by caffeic acid, punicalagin, epicatechin, ECE and PPE during storage. This study evaluated and found the inhibitory effect on the formation of furans and acrylamide in Maillard reactions by the use of some plant extracts and polyphenols.

DETERMINATION OF POLYPHENOLS OF SOME TURKISH HONEYDEW AND NECTAR HONEYS USING HPLC-DAD

The present article was carried out to characterize and compare the phenolic compounds of Turkish honeydew and nectar honeys which have quite different acceptances by consumers and processing type. Phenolic compounds were identified and quantified with High Performance Liquid Chromatography-Diode Array Detector (HPLC-DAD) system by means of 20 phenolic standards. Some differences were observed between honeydew and nectar honeys. While pinocembrin and quercetin were not determined in the honeydew honeys, these flavonoids were present in the nectar honey samples. While the main compound of honeydew honeys was catechin, it was chlorogenic acid for nectar honeys. In addition to this results, statistically significant correlations were detected among the phenolic compounds such as between caffeic acid and chlorogenic acid (r = 0.908), chlorogenic acid and coumaric acid (r = 0.836), and caffeic acid and coumaric acid (r = 0.893) in the nectar honeys. Phenolic profiles of these honeys may provide a marker for determination the botanical origin of honeys.

HPLC-DAD Analysis to Identify the Phenolic Profile of Rhododendron Honeys Collected from Different Regions in Turkey

In this study, phenolic compounds of Rhododendron honey (also known as mad honey) samples collected from the Black Sea Region were identified using high performance liquid chromatography-diode array detector system. The major phenolic substances in Rhododendron honeys were found to be chlorogenic and coumaric acids with the amounts of 0.11–191.54 mg/kg and 0–82.83 mg/kg, respectively. Gallic and ferulic acids were detected in the most honey samples. Additionally, significant correlations were determined between the phenolic substances. The present study showed that Rhododendron honeys contained higher quantities of phenolic acids than flavonoids. Chlorogenic and coumaric acids were the dominant phenolic substances detected in honey samples.

New approaches to determination of HMF.

Several techniques have been used for hydroxymethylfurfural (HMF) detection in foods. Most of these involve the protein hydrolysation step process to determine the presence of organic acid with heat treatment. The affinity and separability of HMF to/from some proteins were exhibited in this study. Also, the dependency of HMF level was determined in the presence of some substances such as reductive and non-reductive sugars, gums and polysaccharides due to high temperature and acidity during the hydrolysation stage. Consequently, the HMF levels of the samples were evaluated separately either by no treatment or by the acid-heat treated method. The HMF amount which was measured by the conventional method was found to be dependent on the sample amount. The binding capacity of HMF to casein was about 10% but did not bind to the gluten in the model system. However it was not released from the caseine by acid hydrolysation in the solvent.

5-hydroxymethyl furfural formation and reaction kinetics of different pekmez samples: effect of temperature and storage

Abstract Pekmez (molasses) is a traditional food commonly produced from grape and other kind of fruit juices by evaporation processes. In this study, 5-Hydroxymethylfurfural (HMF) level of various pekmez samples was investigated during storage at different temperatures. HMF content of apricot, mulberry, carob, grape, Juniperus communis pekmez changed from 133.0 ppm to 1060.5 ppm, from 88.2 to 1921.5 ppm, from 11.1 to 1153.6 ppm, from 75.5 to 2077.0 ppm, from 19.9 to 280.1 ppm throughout eight months storage period, respectively. Samples of pekmez from the Juniperus communis had the minimum k values for each temperature that means HMF formation in these samples were slower than other pekmez types. The kinetic data analysis for HMF formation during storage was performed and an Arrhenius equation was used to determine the effect of temperature on reaction kinetics of 5-HMF formation in pekmez samples. Ea values were found between 10.58–37.73 (kcal/mol). Apricot pekmez was found as the least sensitive sample to HMF formation resulted from temperature changes.

RECOVERY OF BIOACTIVE PHENOLIC COMPOUNDS FROM OLIVE MILL WASTE WATER, POMEGRANATE PEEL, AND EUROPEAN CRANBERRYBUSH (VIBURNUM OPULUS L.) JUICE BY PREPARATIVE MPLC

□ In this study, preparative medium pressure liquid chromatography (MPLC) was used for the purification of some phenolic compounds including hydroxytyrosol, chlorogenic acid, and punicalagin from olive mill waste water (OMWW), European cranberrybush (Viburnum opulus L.) juice, and pomegranate peel, respectively. While the polyphenols of OMWW and European cranberrybush juice were extracted with ethyl acetate (EtOAc), methanol was used for pomegranate peel extraction. At the end of the extraction process, the solvents were removed by rotary evaporator and the residue passed into the water phase. After the centrifugation and microfiltration procedure, the injection of samples was carried out by MPLC. The outflow of the colon was collected at specific periods and the predetermined polyphenols for purification were identified with High-Pressure Liquid Chromatography with UV Detector (HPLC-UV). After the collection of defined fractions, chlorogenic acid, and punicalagin were concentrated with a rotary evaporator and transformed into particle form by freeze drying. Hydroxytyrosol was produced as concentrated liquid by using a rotary evaporator. The purities of the obtained compounds were determined as 90.2%for hydroxytyrosol, 92.5%for chlorogenic acid, and 97.1%for punicalagin. Moreover, the inhibition percentages of these compounds on 2,2-diphenyl-1-picrylhydrazyl (DPPH) were established, respectively, as 76.01, 84.90, and 94.64.