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Featured researches published by Nevzat Konar.


Critical Reviews in Food Science and Nutrition | 2018

Oleogels, a promising structured oil for decreasing saturated fatty acid concentrations: Production and food-based applications

Halime Pehlivanoglu; Mehmet Demirci; Omer Said Toker; Nevzat Konar; Salih Karasu; Osman Sagdic

ABSTRACT Oils and fats are widely used in the food formulations in order to improve nutritional and some quality characteristics of food products. Solid fats produced from oils by hydrogenization, interesterification, and fractionation processes are widely used in different foodstuffs for these aims. In recent years, consumer awareness of relation between diet and health has increased which can cause worry about solid fat including products in terms of their high saturated fatty acid and trans fatty acid contents. Therefore, different attempts have been carried out to find alternative ways to produce solid fat with low saturated fatty acid content. One of the promising ways is using oleogels, structuring oils with oleogelators. In this review, history, raw materials and production methods of the oleogels and their functions in oleogel quality were mentioned. Moreover, studies related with oleogel usage in different products were summarized and positive and negative aspects of oleogel were also mentioned. Considering the results of the related studies, it can be concluded that oleogels can be used in the formulation of bakery products, breakfast spreads, margarines, chocolates and chocolate-derived products and some of the meat products.


Food Chemistry | 2018

Formulation of dark chocolate as a carrier to deliver eicosapentaenoic and docosahexaenoic acids: Effects on product quality

Omer Said Toker; Nevzat Konar; Ibrahim Palabiyik; Haniyeh Rasouli Pirouzian; Sirin Oba; Derya Genc Polat; Ender Sinan Poyrazoglu; Osman Sagdic

In this study, dark chocolate enriched with EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) was developed using various forms and origins. Quality characteristics such as physical, thermo-gravimetric, rheological, textural and sensory properties of chocolates were investigated. The highest EPA/DHA stability was determined in samples prepared by free-flowing powder and microencapsulated forms of omega-3 fatty acids (FA). The L∗ and C∗ values varied from 32.16-33.37 and 7.45-8.09, respectively for the all samples. Hardness values ranged between 6422 and 8367 N and the use of EPA/DHA in the triglyceride form caused softer chocolate whereas control sample was the hardest sample. Melting and rheological properties were not significantly affected by the studied EPA/DHA sources (P < 0.05). Microencapsulated EPA/DHA added chocolate was the most preferred source whereas sample with algae oil showed the lowest acceptability. According to the results, dark chocolate can be used for delivering omega-3 FA by considering their origin and physical form.


International Journal of Food Properties | 2017

Stability of lactic acid bacteria in synbiotic sugared and sugar-free milk chocolates

Omer Said Toker; Derya Genc Polat; Osman Gokhan Gulfidan; Nevzat Konar; Ibrahim Palabiyik; Alican Akcicek; Ender Sinan Poyrazoglu; Osman Sagdic

ABSTRACT In this study, stability of Lactobacillus acidophilus and L. paracasei in synbiotic sugared and sugar-free milk chocolates within 90-day storage was investigated, considering inline as prebiotic. Probiotic bacteria inoculation at 9.0 log cfu/25 g and usage of inulin with Degree of Polymerisation (DP)<10 and DP > 23 at a concentration of 9.0 g/100 g were investigated. At the end of 90 days, at least 6.5 log cfu/25 g probiotic bacteria was determined in the samples containing L. acidophilus, whereas this value was determined as 5.9 log cfu/25 g for L. paracasei. Therefore, it was concluded that L. acidophilus was more stable in terms of viability level in the milk chocolates prepared by sugar, maltitol, and inulin DP was effective on viability levels of probiotics (p < 0.05). Moreover, inulin DP was also found effective on water activity, melting, rheological and textural properties and colour of milk chocolate (p < 0.05). Quality parameters were affected by inulin DP, except rheological properties.


International Journal of Food Engineering | 2017

Effect of Inulin DP on Various Properties of Sugar-Free Dark Chocolates Containing Lactobacillus paracasei and Lactobacillus acidophilus

Nevzat Konar; Ibrahim Palabiyik; Omer Said Toker; Derya Genc Polat; Sinem Sener; Alican Akcicek; Osman Sagdic

Abstract In the present study, the effect of different polymerization degree of inulin on the quality parameters of conventional and sugar-free dark chocolate products as well as on the vitality of probiotics used in the chocolates were investigated. To produce sugar-free dark chocolates prepared with the addition of maltitol, Lactobacillus paracasei/L. acidophilus and inulin with DP higher than 23 and lower than 10 were used as probiotic and prebiotic agents, respectively. After 90 day of storage, more than 6 log cfu/25 g probiotics were observed in the chocolates produced by supplementing of 9 log cfu/25 g probiotics. Considering the probiotic level for both conventional and sugar-free dark chocolate, the highest probiotic level was observed in the samples prepared from L. acidophilus and inulin with DP<10. In addition, inulin with DP<10 was found as more suitable in terms of rheological characteristics of the samples. Other quality parameters (texture, colour, melting profile and water activity) changed in narrow range which was allowable when compared with the control samples. Consequently, sugar-free chocolate containing L. paracasei and L. acidophilus could be produced which might satisfy the expectations of the consumers and appropriate to industrial production similar to conventional chocolate. The findings of the present study highlighted the importance of the selection of the most suitable prebiotic/probiotic combination for maximizing probiotic level in the chocolate products.


GIDA / THE JOURNAL OF FOOD | 2018

βv TOHUMLAMA TEKNİĞİNİN ALTERNATİF PRE-KRİSTALİZASYON YÖNTEMİ OLARAK SİNBİYOTİK SÜTLÜ ÇİKOLATA ÜRETİMİNDE KULLANIMI

Omer Said Toker; Haniyeh Rasouli Pirouzian; Nevzat Konar; Derya Genc Polat

Bu calismada, inulin ve Lactobacillus acidophilus iceren sinbiyotik sutlu cikolata, konvensiyonel temperlemeye alternative olarak β v tohumlama teknigi kullanilarak uretilmistir. Bu amacla, cikolata uretiminde β v tohumlari farkli oranlarda (0.5-1.50%) kullanilmistir. β v tohum konsantrasyonunun cikolata orneklerinin su aktivitesine, nem miktarina, sertlik degerine, renk ve reolojik ozelliklerine etkisi arastirilmis ve konvansiyonel temperleme ile uretilen ornegin kalite ozellikleri ile karsilastirilmistir. Cikolata orneklerinin su aktivitesi ve nem icerikleri birbirlerine oldukca yakin bulunmustur. Sertlik degeri, β v tohum konsantrasyonundan istatistiksel olarak onemli sekilde etkilenmistir. Eriyik cikolata orneklerine ait akma siniri ve plastic viskozite degeri, tohum konsatrasyonu arttikca azalmistir. Orneklerin kalite parametreleri, β v tohumlamanin alternatif pre-kristalizasyon teknigi olarak urunlerin kalite ozelliklerine zarar vermeden kullanilabilecegini gostermistir. Bu sekilde cikolata uretiminde ekonomik kar ve hizli uretim saglanmis olacaktir.


Archive | 2017

A Novel Delivering Agent for Bioactive Compounds: Chewing Gum

Ibrahim Palabiyik; Haniyeh Rasouli Pirouzian; Nevzat Konar; Omer Said Toker

Functional food concept is one of the hot topics in the food industry. In recent years, people want to consume food products having health beneficial effect as well as nutritive characteristics. Regarding functional food development, foods have also advantages and disadvantages in terms of delivering bioactive compounds due to formulation (interaction of the bioactive compound with other ingredients, calorie value provided) and production process (mechanical and thermal processes applied during production). When considering the factors restricting usage of the food products as a delivery system, chewing gum is one of the most up-and-coming products in many aspects: (i) simplicity of the formulation prevents the activity of bioactive compound by interaction, (ii) level of mechanical and thermal stresses applied during production, (iii) enabling the release of targeted molecule in a controlled and sustained manner, (iv) different consumption behavior abolishing calorie intake concern since it is only chewed without swallowing, and (v) holding time in mouth. Usage of encapsulated bioactive compounds can improve the release behavior of the functional ingredient. Mastication process and the formed matrix/structure of the chewing gum also influence the release of the bioactive compounds. The researches about improving functionality of chewing gum have indicated that chewing gum can be used as a delivery system for transportation of the desired bioactive compound to body/targeted site. However, during functional chewing gum development, formulation, production process, mastication process, and type/form of bioactive compounds should be considered to achieve the product with required functional properties.


International Journal of Food Properties | 2017

Rheological and melting properties of sucrose-free dark chocolate

Sirin Oba; Omer Said Toker; Ibrahim Palabiyik; Nevzat Konar; Hamza Goktas; Yusuf Cukur; Nevzat Artık; Osman Sagdic

ABSTRACT In this study, sugar-free dark chocolate was produced from isomalt and maltitol by βV seeding technique as an alternative to conventional tempering process. The effect of βV seed concentrations on the particle size distribution (PSD), textural, rheological and melting properties of the final products were examined and the results were compared with those of conventional sugar-free dark chocolates. For this aim, conched dark chocolates were melted and crystallised with βV seeds which were added at different concentrations (0.5, 0.6, 0.7, 0.8, 0.9 and 1.0%, m/m). According to the results PSD, hardness, rheological and melting properties were not influenced by seeding technique compared to conventional tempering method. On the other hand, inverse relation was observed between largest particle size and specific surface area of the samples. Hardness values of isomalt and maltitol including samples were found to change between 15.33–18.79 N. Casson model best described the flow behaviour of the sugar-free chocolates. As a result, seeding technique can be used as an alternative method in sugar-free dark chocolate production in terms of quality and physical properties.


Trends in Food Science and Technology | 2016

Chewing gum: Production, quality parameters and opportunities for delivering bioactive compounds

Nevzat Konar; Ibrahim Palabiyik; Omer Said Toker; Osman Sagdic


Trends in Food Science and Technology | 2016

Improving functionality of chocolate: A review on probiotic, prebiotic, and/or synbiotic characteristics

Nevzat Konar; Omer Said Toker; Sirin Oba; Osman Sagdic


Lwt - Food Science and Technology | 2018

Developing functional white chocolate by incorporating different forms of EPA and DHA - Effects on product quality

Omer Said Toker; Nevzat Konar; Haniyeh Rasouli Pirouzian; Sirin Oba; Derya Genc Polat; Ibrahim Palabiyik; Ender Sinan Poyrazoglu; Osman Sagdic

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Omer Said Toker

Yıldız Technical University

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Osman Sagdic

Yıldız Technical University

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Alican Akcicek

Yıldız Technical University

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Hamza Goktas

Yıldız Technical University

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