Pekmez Production Research Articles

Sweet pomegranate pekmez production: Effect of different production methods and activated carbon treatment on some quality parameters and 5‐hydroxymethyl furfural formation

In the present study, “sweet pomegranate pekmez” (PP), was produced by three different methods as open pan evaporation (OPE), application of activated carbon prior to open pan evaporation (AC), and vacuum evaporation (VE). The effects of activated carbon treatment and production methods on pH, density, soluble solids, water activity, total phenolic content, HMF formation, mineral content, and texture characteristics were investigated. Textural properties of PP increased with increasing soluble solids content. HMF was not detected in AC and VE products. HMF content of OPE product was measured as 2.77 ± 0.28 mg.100 g. Activated carbon treatment resulted in significant reductions in mineral, HMF, and TPC contents of pekmez samples. HMF formation kinetics of PP was investigated at various accelerated storage temperatures. HMF formation was well described by the zero-order reaction model among five kinetic models applied. The rate of reaction was determined as highly temperature-dependent by an Arrhenius equation. Practical applications In recent years, consumer interest and demand for potentially health-promoting products has motivated the production of such food products. In this context, in this study, sweet pomegranate pekmez is introduced as a potentially healthy product produced by different methods, and the production stages and conditions that may enlighten the industrial production of this traditional product are provided. In addition, the application of activated carbon used in the production of pekmez has been presented as an alternative method to reduce the potential formation of HMF during heat treatment.

Production of grape pekmez by Ohmic heating-assisted vacuum evaporation.

Pekmez is a concentrated syrup-like food conventionally produced by vacuum evaporation process from sugar-rich fruits. In this study, the applicability of grape pekmez production by ohmic heating assisted vacuum evaporation (ΩVE) method was investigated. Conventional vacuum evaporation (CVE) and ΩVE methods were compared in terms of physicochemical properties, HMF (5-hydroxymethylfurfural) contents, rheological properties, and energy consumptions. ΩVE was run at four different voltage gradients (17.5, 20, 22.5, and 25 V/cm). Total process times for grape pekmez production were determined as 57, 28.5, 32, 39, and 50 minutes for CVE, ΩVE (25 V/cm), ΩVE (22.5 V/cm), ΩVE (20 V/cm) and ΩVE (17.5 V/cm), respectively. Energy consumption of CVE method was higher than ΩVE method for all voltage gradients. Energy efficiency increased as the voltage gradient increased. There was no significant difference between CVE and ΩVE methods for HMF contents. The results show that the ΩVE method could be an alternative to the CVE process for grape pekmez production.

USE OF MULBERRY POMACE AS SUBSTRATE FOR CITRIC ACID PRODUCTION BY Aspergillus niger MT-4

Mulberry pomace (MP) is a waste material obtained after the production of pekmez, a traditional Turkish food. This study was performed to test the usability of MP as substrate for citric acid (CA) production by Aspergillus niger MT-4 for the first time. In the study, some culture conditions were also optimized to increase CA production in MP-based medium. Moisture, total carbohydrate, water-soluble carbohydrate, protein, lipid and ash contents of MP were determined as 31.1, 47.1, 1.3, 13.4, 1.8 and 1.4%, respectively. Experiments were carried out in 250 mL flasks containing 100 mL of production medium. Optimal MP concentration for both fungal biomass (FB) and CA production was determined as 120 g/L. All concentrations of KH2PO4 added to MP-based medium were found to decrease CA production but increase FB production. Optimal concentrations of MgSO4 and (NH4)2SO4 for CA production were found as 1 and 2 g/L, respectively. The other optimal parameters were determined as an initial pH of 7.0 and an incubation period of 5 days. Under the optimized culture conditions, the amount of CA produced was determined as 24.6 g/L. On day 5, Yp/s, Yp/x and Yx/s were calculated as 0.2 g CA/g MP, 1.43 g CA/g FB and 0.14 g FB/g MP, respectively.

Improved qualitative properties of pear pekmez by natural zeolite treatment during production process

AbstractThe effect of zeolite treatment on color change, 5‐hydroxymethyl furfural (HMF), total phenolic compounds (TPCs), ionic composition and texture of sweet pear pekmez was investigated for two different zeolite concentrations during pekmez production. HMF was not detected in clarified pear juice and pekmez samples subjected to 5 g/L (5ZP) and 10 g/L (10ZP) zeolite adsorption. HMF content of pekmez sample without zeolite treatment (PP) was measured as 2.76 ± 0.07 mg/kg. The addition of zeolite just after the clarification results in the reduction of the HMF content of pekmez samples. The highest TPC was determined as 4,958.1 ± 167 mg GAE/kg dry weight in PP sample. Application of zeolite together with conventional clarification resulted in 31.4% and 33.2% reduction in TPC of 5ZP and 10ZP, respectively, compared to PP samples. Zeolite application improved the color quality of pekmez samples. While the amount of fluoride, chloride, bromide, and potassium decreased with the zeolite treatment, the amount of calcium, sodium and magnesium in pekmez samples increased significantly. Zeolite treatment did not significantly affect the texture of the samples.Practical applicationsPekmez is concentrated fruit juice with long shelf life and high nutritional value. HMF formation is a very important problem that must be prevented or eliminated in the pekmez production process. This study provides the pear pekmez production process and determination of some important quality features such as color change and amount of HMF and metal ions. Besides, zeolite treatment is applied for the first time during pekmez processing. The results reveal that zeolite treatment is useful means to reduce undesirable metal ions and HMF formation during pekmez production while improving the color quality. Consequently, the use of zeolite in pekmez production has great potential to produce the high quality and safe pear pekmez.

The influence of processing and clarifier agents on the concentrations of potentially toxic elements (PTEs) in pekmez (a grape molasses-like syrup).

The changes in some potentially toxic elements (PTEs) including lead (Pb), cadmium (Cd), arsenic (As), iron (Fe), zinc (Zn), and copper (Cu) during pekmez (grape molasses-like syrup) processing and the utilization of various types of clarifiers (white soil, bentonite, and gelatin) in two levels (1.5 and 3% w/w) were analyzed. The average concentrations of Pb, Cd, As, Fe, Zn, and Cu in grape samples were measured as 0.055 ± 0.005, 0.030 ± 0.002, 0.044 ± 0.002, 2.882 ± 0.013, 2.372 ± 0.088, and 1.194 ± 0.01μgg-1. During pekmez production, the range of changes in Pb, Cd, As, Fe, Zn, and Cu was -43.38% to 40.25%, -55.49% to 0.23%, -76.15% to 1.80%, -74.15% to 58.47%, -40.55% to -18.12%, and -83.16% to -21.39%, respectively. The effect of the clarification process on the PTEs depended on the type and concentration of both PTE and clarifier agent used while the incorporation of gelatin resulted in a significant reduction in all of PT. Graphical abstract.

Gastronomi ve Moleküler Gastronomi Açısından Üzüm Pekmezi

Molecular gastronomy is a scientific field that contains the food materials, food ingredients, food additives, method of preparation of the food and appreciated by consumers. Grape pekmez, one of the traditional foods subject to our study, is the thick product obtained by reducing the acidity of unfermented fresh or raisin extracts by suitable methods and then thickening under vacuum or in the light in accordance with the technique. Although, today pekmez is generally produced industrially, it is also produced according to local methods partly in rural areas. It is also an important food in terms of nutrition and health by meeting most of the daily requirement of calcium, iron, potassium and magnesium.In this study; it was tried to be explained the changes in chemical and biochemical components which appear positively or negatively in pekmez during production that is molecular gastronomic transformations from raw material to finished product by focusing on the production stages. Thus, the production of pekmez was assessed in the gastronomic and molecular gastronomic directions.

Assessment of processing impacts and type of clarifier on the concentration of ochratoxin A in pekmez as a conventional grape-based product

Pekmez can be considered as one of the most favored traditional grape's products, however, it can be contaminated with ochratoxin A (OTA). In this regard, for the first time, the effects of unit operations including washing, juicing (crushing and pressing), clarification with the aid of various clarifier (bentonite, white soil, and gelation) and boiling on the concentration of OTA in artificially spiked pekmez samples were investigated. According to findings, all unit operations utilized in pekmez production led to OTA reduction while the range - mean of OTA reduction in washing, juicing (crushing and pressing), clarification and boiling stages were recorded as 7.36–16.53%-12.19 ± 4.60%, 2.51–8.32%-6.13 ± 3.16%, 4.24–16.55%-16.38 ± 10.25%, and 1.54–37.43%-10.44 ± 3.85%, respectively. Among the clarifiers used, the highest (23.76 ± 7.90%) and lowest (11.48 ± 9.37%) mean reduction of OTA was attributed to gelatin and bentonite, respectively. Therefore, the utilization of gelatin could remove higher levels of OTA. Generally speaking, the OTA overall reduction range and mean during the pekmez production process was 25.84–54.67 and 37.52 ± 6.54%, respectively, which depended on the initial concentration of OTA and unit operations, the type and concentration of clarifier. The optimum condition of OTA reduction was obtained in samples containing initial OTA content of 5 μg kg−1 which were clarified with 3% of gelatin.

Changes in aflatoxins content during processing of pekmez as a traditional product of grape

The current study was aimed to investigate the changes in aflatoxins (AFs) content during the production of pekmez. In this context, the artificially spiked grape samples in levels of 2.5, 5, and 7.5 μg/kg of aflatoxin B1 (AFB1), and 0.5, 1 and 1.5 μg/kg of aflatoxin B2 (AFB2), G1 (AFG1) and G2 (AFG2) were processed by the conventional procedure and after each step, AFs levels were measured using HPLC-FD. Among different unit operations, the lowest reduction in AFs (8.2, 14.8, 12.4, and 22.7% for AFB1 and AFB2, AFG1, and AFG2, respectively) was obtained for crushing and pressing stages. The corresponded values for reduction average of AFB1, AFB2, AFG1, and AFG2 during washing step was measured as 19.3%, 22.2%, 23.7%, and 34.3%, respectively. Clarification stage was identified as the most effective step in the reduction (63.6%) of AFs. However, the reduction strongly depended on the type and concentration of clarifier as well as initial aflatoxin level. A significant difference between the assessed clarifiers (gelatin, bentonite and white soil) was observed, while the highest efficiency was demonstrated by gelatin. In general, levels of AFB1, AFB2, AFG1, and AFG2 during pekmez production were decreased about 60.4, 76.7, 76.3, and 86.7%, respectively.

Production and Characteristics of a Traditional Food: Molasses (Pekmez)

<p><em>Pekmez, which has been produced for a long time in Turkey, is one of the popular and traditional Turkish foods (Tosun & Üstün, 2003</em><em>; Celik & Surucuoglu, 2005; Türkben, 2016)</em><em>. </em><em>Pekmez is produced primarily from grapes (Arici et al., 2004; Alpaslan & Hayta, 2002; Sürücüoglu & Celik, 2005; Batu et al., 2007; Dag, 2016; Demir, 2014). Molasses are usually preferred for breakfast in winter (Kusçu & Bulantekin, 2016). Suitable for juice production, sugar content, acid value and ripening time are suitable for grape molasses production. Turkey, approximately 4185.126 tons of grapes are produced per year (TUIK, 2012), and approximately 30% of the grapes produced in Turkey are used for pekmez, wort and sausage with pekmez production in a year. In this study, some information is given on the history of Molasses, production stages, its types, effects on health and the relevant regulations and in terms of product chemical and microbiological characteristics.</em></p>

Production and Characteristics of a Turkish Traditional Food in Another Country (Jonkoping-Sweden): Molasses

<p><em>Pekmez, which has been produced for a long time in Turkey, is one of the popular and traditional Turkish foods (Tosun & Üstün, 2003</em><em>; Celik & Surucuoglu, 2005)</em><em>. Although it is not very common, it is being tried in houses and production places in some countries where Turks live. </em><em>Pekmez is produced </em><em>primarily from grapes (Alpaslan & Hayta, 2002; Sürücüoglu & Celik, 2005; Batu et al., 2007). Grapes suitable for fruit juice yield, sugar content, acid value and ripening time are suitable for molasses production.Turkey</em><em>, approximately 4185.126 tons of grapes are produced per year (TUIK, 2012), and approximately 30% of the grapes produced in Turkey are used for pekmez, wort and sausage with pekmez production in a year. In this study, some information is given on Molasses (produced in another country), production stages, effects on health and the relevant regulations and in terms of product chemical and microbiological characteristics. </em></p>

The effects of production methods and storage on the chemical constituents of apple pekmez

The purposes of this study were to investigate the effects of two different pekmez production methods namely open pan evaporation (OPE) and vacuum evaporation (VE) on the final products, and to observe the changes in constituents as well as aromatic components after 4months of storage. The initial and poststorage (4months) 5-hydroxymethyl furfural (HMF) content in OPE apple pekmez were respectively 5.48, and 7.04mg/kg. No HMF was detected in VE apple pekmez. Both initial and poststorage content of phenolic compounds was higher in VE pekmez compared to OPE pekmez. The effects of production methods and storage time were statistically significant on phenolic compounds in apple pekmez. The content of all analyzed minerals except calcium has significantly decreased in pekmez compared to raw material on dry weight basis. OPE resulted in a 55.97% loss in the amount of ascorbic acid, whereas the loss in VE has been 23.45%. Poststorage loss in ascorbic acid has respectively been 69.54, and 89.28%, for VE and OPE samples. None of the aromatic components of fresh apple was detected in pekmez.

Changes in the physicochemical and antioxidant characteristics of watermelon during pekmez production

Watermelon is a health-promoting fruit in terms of being an excellent source of lycopene and gastronomically pleasing. However, its consumption is restricted to a certain season because it is usually consumed as fresh. Therefore, utilisation of watermelon by processing into a more stable product that is available throughout the year would be beneficial. In this research, watermelon was utilised by processing into pekmez (concentrated juice) by concentrating the juice in open boilers until 68°Brix, and changes in some physicochemical properties, colour and antioxidant characteristics that occur during pekmez production were determined. Sensory evaluations for pekmez products were also carried out. It was determined that the redness, yellowness, pH, titratable acidity and formol number values increase, whereas brightness, total sugar and invert sugar values decrease during processing the fruit into pekmez. Hydroxymethyl furfural was produced slightly during processing. Lycopene, total phenolic content and antioxidant activities of pekmez and juice were also compared. Although phenolic content was significantly (P<0.05) lower in pekmez samples, they exhibited significantly (P<0.05) higher antioxidant activity than the juice in terms of both 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and ferric reducing antioxidant power value.

Comparison of mineral contents of mulberry (Morus spp.) fruits and their pekmez (boiled mulberry juice) samples

Mineral contents of four mulberry fruits and their pekmez samples growing particularly in the Malatya province in Turkey were determined by inductively coupled plasma atomic emission spectrometry. All samples contained high amounts of calcium, potassium, magnesium, sodium, phosphorus and sulphur. The highest mineral concentrations for mulberry fruits were measured between 1,873.65 and 4,437.52 mg/kg for calcium, 10.860 and 15.269 g/kg for potassium, 904.48 and 1033.11 mg/kg for magnesium, 115.29 and 252.33 mg/kg for sodium, 1.831 and 2.329 g/kg for phosphorus, and 493.35 and 642.25 mg/kg for sulphur. These values for pekmez samples varied between 135.76 and 575.84 mg/kg for calcium, 5.853 and 8.146 g/kg for potassium, 187.96 and 389.86 mg/kg for magnesium, 20.40 and 43.55 mg/kg for sodium, 285.10 and 517.72 mg/kg for phosphorus and 121.21 and 303.57 mg/kg for sulphur. Potassium content was high compared with other minerals. The highest potassium level was 15.269 g/kg for red mulberry fruit, whereas the lowest potassium content was 5.8523 g/kg for black mulberry pekmez sample. The mineral content of pekmez samples of black and red mulberry fruits decreased at the important levels compared with those of white mulberries during pekmez production. As a result, mulberry fruits and their pekmez samples contain nutrient elements of vital importance in man's metabolism.

Enek Pekmez Production from Juniper “Fruits” by Native People on the Taurus Mountains in Southern Turkey

Enek Pekmez Production from Juniper “Fruits” by Native People on the Taurus Mountains in Southern Turkey

Antioxidant activity of cherry laurel fruit ( Laurocerasus officinalis Roem.) and its concentrated juice

Cherry laurel fruit and its concentrated juice (pekmez) were examined for their antioxidant activities using different free-radical scavenging activity tests [hydrogen peroxide, superoxide radical, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical], together with reducing power and inhibition of oxidation of human low-density lipoprotein cholesterol. On a fresh weight basis, pekmez exhibited a significantly ( P < 0.01) higher antioxidant activity than that of cherry laurel fruit in most cases. However, on a dry weight basis hydrogen peroxide and DPPH radical scavenging activities, and reducing power were significantly higher ( P < 0.01) in cherry laurel fruit than in its pekmez, with some exceptions, thus indicating possible destruction of antioxidative compounds during pekmez production. This was also partly due to the moisture content of these two samples. On the basis of the results presented, it is suggested that the intake of cherry laurel fruit and pekmez rich in phenolics would have beneficial effects in improving amelioration of degenerative diseases caused by oxidative stress. Therefore, both cherry laurel fruit and pekmez might be considered as functional food ingredients and nutraceuticals.

Pekmez: A Traditional Concentrated Fruit Product

Pekmez is a traditional Turkish food made by using different fruits such as grape, mulberry, fig, apple, and sugar beet. There are two different kinds of pekmez, either liquid pekmez or solid pekmez, produced in Turkey. The stages for processing liquid pekmez for all fruits, except mulberry, include washing, sorting, crushing, pressing, and boiling. By using liquid pekmez, and solidifying and bleaching its agents solid pekmez is produced. Pekmez is a healthful food due to its nutritional content and is used as a main source of energy based on its chemical composition. The carbohydrates in pekmez are generally in the form of natural sugars like glucose and fructose, which is nutritionally important for babies, children, sportsmen, and active workers. Pekmez production and its chemical composition should be adapted to the modern food technology and food safety requirements; at the same time, this adaptation should conserve the authentic properties of the product.

PRODUCTION OF LIQUID AND WHITE SOLID PEKMEZ IN TURKEY

ABSTRACT The research was carried out to evaluate gelling and bleaching agents for white solid pekmez production. Grape juice with 26% total soluble solids as °Brix was used for the production of pekmez. Acidity was reduced with the application of sterile white soil containing 70.4% CaCO3, followed by tannin–gelatin clarification and filtration. The grape juice was concentrated to 76% total soluble solids by vacuum. Gelling treatments were designed to produce a solid pekmez by adding high or low methoxyl pectins or carboxymethylcellulose (CMC). It was found that sufficient gelling could be achieved using less than 0.5% CMC and 1% for either pectin. Also, a desirable white color was obtained with 1.5% soapwort juice and 3% egg white with the combination of 1% pectins.

Compositional Characteristics and Antioxidant Components of Cherry Laurel Varieties and Pekmez

ABSTRACT: Cherry laurel is a popular fruit in the Black Sea region of Turkey. Two native cherry laurel varieties, namely kiraz and findik, together with pekmez (made from concentrated juice of the kiraz variety by boiling/ heating) were examined for their proximate composition, antioxidant activity, total anthocyanins, phenolics, and carotenoids, as well as phenolic acids and sugar composition. A linear correlation existed between antioxidant activity and total content of phenolics (r2= 0.99). The antioxidant activity and total content of phenolics were the highest in pekmez, followed by findik, and kiraz. A significant (P < 0.01) proportion of anthocyanins and carotenoids was lost during heat processing in the production of pekmez. Ten phenolic acids (free and bound) and 6 sugars were identified among samples. These results suggest that cherry laurel varieties and pekmez serve as a good source of natural antioxidant, which could potentially be used in food and nutraceutical supplement formulations.

The fate of ochratoxin A during the Pekmez production from mouldy grapes

The grape juices produced from mouldy grapes that are contaminated naturally with OA between 2.1 and 9.8 μg/l were used in pekmez production. In the processing steps of pekmez, changes in OA amount were examined. The amounts of OA in pekmez samples were found to be 5–6 times higher than OA amount of grape juice. The dry matter (%), total sugar (%) and pH values were 18.93, 17.82 and 3.36 at the beginning of the experiment while they were 71.42, 67.35 and 3.91 at the end of the experiment, respectively.

Variation of copper, iron, and zinc levels in Pekmez products.

Pekmez is a very popular and traditional food products in Turkey and it is produced in almost every region of the country. Fruits containing high sugar like mulberry, plum, apple, and mainly grape are used as raw material in the production of Pekmez. According to investigations in Turkey, about 20% of all growth grapes were used in Pekmez production in 1982, this ratio was about 18% in 1992 (Nas and Nas, 1987; Batu and Aktan, 1992; Batu, 1993). Pekmez has been produced since ancient but its production technique has not been developed. Fruit-juice, which was obtained with different techniques, used in producing Pekmez, is boiled with the Pekmez soil (this soil is added to the grape-juice in order to neutralize its acidity and contains 50-90% of CaC03, and it has various colors from white to light brown). After than, it is concentrated in the boiler on naked flame after filtration. This concentrated fruit-juice is a very clear and brownish