Emrah Kırtıl

The focus of interest of this research was freezing preservation of green bean and strawberry in a home type freezer. Freezing time and freezing rates were determined from the cooling curves obtained experimentally. Home type freezing provided slow freezing rate. NMR Relaxometry measurements showed that freezing did not keep the cellular integrity in strawberries and green beans due to structural damage and extracellular ice formation. Packaged samples were stored at −27 °C for approximately 3 months. Although total phenolic content, antioxidant activity and color changes of samples were not significant, significant L-ascorbic acid losses were determined for 13 weeks' frozen storage of strawberries and green beans. Home freezing should be done at appropriate freezing rate to preserve the texture and the nutritional content of fruits and vegetables.

Time domain nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) are well-known non-destructive characterization techniques that are used to evaluate food quality. Time domain NMR is primarily based on relaxation and diffusion measurements from the signal coming from the whole sample whereas MRI enables visualization of the interiors of intact foods on a macroscopic scale without disturbing the sample based on the differences on relaxation and diffusion. A common perception that using NMR/MRI for testing food is costly is no longer valid with the advances in low-field bench top NMR/MRI instruments. This short review paper discusses the most recent developments and examples of time domain NMR and MRI based sensors for different food applications.

tr (M.H. Öztop) 0 312 210 56 32 0 312 210 27 67 ÖZET Lipozomlar farmasötik uygulamalar başta olmak üzere yıllardır birçok uygulamada kapsülasyon maddesi olarak kullanılan çift katmanlı polar lipitlerden oluşan keseciklerdir. Doğal fosfolipit kompozisyonları olan lesitinlerden elde edilen bu keseciklerin gıdalarda kullanımı son yıllarda artış göstermiştir. Lipozomların gıdalarda kullanımı sonucunda kapsüllenmiş maddenin stabilitesini arttırması ve bu maddenin bulunduğu ortamdaki diğer maddelerle etkileşimini minimize etmesi gibi faydalarının yanı sıra; diğer kapsülasyon maddelerine kıyasla oluşturulma metotlarının basitliği, tamamen doğal bileşiklerden oluşturulması gibi özellikleri, lipozomları birçok enkapsülasyon sisteminden ayıran belirgin özelliklerdir. Ancak lipozomların gıda uygulamalarında kullanılan yüksek sıcaklık, basınç, pH ekstremleri ve fiziksel karıştırma gibi stres koşulları karşısında stabilitesini koruyabilmesi zordur. Bu konuda süregelen araştırmalar, lipozom stabilitesinin artırılması için uygulanabilecek metotların varlığını göstermiştir. Bu derleme, gıda bilimi konusunda çalışan araştırmacılara, lipozomların yapısı, kullanımının sağladığı avantajlar, oluşturma metotları, karakterizasyonu, stabilite sorunları ve gıdalarda uygulama alanlarıyla ilgili bilgi vermek ve lipozomları bir kapsülasyon maddesi olarak kullanmak amacında olan araştırmacılara da yol gösterecek bir kaynak olmayı hedeflemiştir. ABSTRACT Liposomes are polar lipid bilayers vesicles used in pharmaceutical applications for years. These spherical vesicles are manufactured from natural phospholipid compositions known as lecithins. Their utilization in foods have recently attracted some interest. Using liposomes as encapsulating agents in foods provides a number of advantages like increased stability for the active agent and minimized interaction of capsuled material with the surrounding medium. However, what sets liposomes apart from other encapsulation agents is the ease of capsulation and its natural composition. Nevertheless, the fragile nature of liposomes poses some challenges with their use under extremes of temperature, pH or pressure. Studies have shown that a number of methods could help to increase liposomes' stability. This review is written with the purpose of providing food scientists, who plan to use liposomes as an encapsulation agent, with a Turkish source covering the chemical and physical structure of liposomes, the advantages they provide, production and characterization methods, stability issues, and their use in food related applications.

Keywords: CalCl 2 /pectin methyl esterase infusion Mangoes 1D/2D NMR relaxometry Freezing This study describes the use of Nuclear Magnetic Resonance (NMR) relaxometry to understand the effect of pec-tin methyl esterase (PME) + CaCl2 infusion under different conditions on cell integrity of fresh-cut and frozen– thawed mangoes. Infusion experiments were performed at: atmospheric pressure, vacuum conditions of 50 kPa and 10 kPa. For NMR relaxometry experiments T 2 (spin–spin relaxation time), T 1 (spin–lattice-relaxation times) and 2D T 1 –T 2 experiments were performed. Results showed that, as the severity of the vacuum treatment increased, the relaxation times changed significantly (p b 0.05). The number of compartments observed in 1-D relaxation spectra of fresh and frozen–thawed mangoes changed with different treatments. The changes in relaxation times were explained due to formation of a gel formed by the interaction of pectin and calcium. 2D T 1 –T 2 relaxation maps showed that compartmentalization was retained after vacuum treatment even for frozen–thawed samples. The study showed that NMR relaxometry is a useful tool to analyze the cell integrity of mangoes exposed to different treatments.

To prolong the shelf life of foods, it is crucial to minimize the rates of biochemical, enzymatic, and microbial degradation reactions. Commonly, this is achieved by ensuring proper sanitation conditions during slaughter or harvesting, processing foods to reduce water activity and damage enzyme functionality, and providing optimum temperature and relative humidity conditions during storage (Kader et al., 1989). Despite these precautions, air surrounding the foods continues to provide a suitable medium for oxidative rancidity reactions, as well as growth of aerobic microorganisms. Hence, alteration of the atmosphere around the food could help preserve its quality. Modified atmosphere packaging (MAP) is defined as the enclosure of a packaged food with an optimal gas composition that is specifically designed to extend its shelf life and is different from atmospheric gas composition (Church and Parsons, 1995). In controlled atmosphere storage (CAS), a fixed predetermined concentration of gases is maintained by constant addition or removal of gases during storage of unpackaged foods. In modified atmosphere (MA), unlike controlled atmosphere systems, no further control is exerted over the food after modification of the initial gas composition (Robertson, 2012; Kader et al., 1989). The positive effects of MA on preserving freshness of foods were first reported in 1821, when Jacques Etienne Berard (a professor at School of Pharmacy at Montpellier in France) claimed that storage of fruits and vegetables under low O 2 concentrations retarded ripening (Robertson, 2012). First commercial applications involved the use of CAS to safely transport fruits in the holds of ships under decreased O 2 concentrations (Davies, 1995; Mullan and McDowell, 2003). The increasing research on the subject has made commercial packaging application available by early 1970s. The initial commercial applications concentrated on red meat, bacon, fish, processed meats, and cooked shellfish. Today, the high consumer demand for longer-shelf-life foods without the addition of preservatives has made MAP available for a wide range of foods including

The capability of seed extracts in stabilizing emulsions has particularly received interest in recent years. Upon soaking quince seeds into water, biopolymers inside the seeds are extracted to water, forming mucilage. This study investigates the physical stability, rheology and microstructure of oil (sunflower oil) in water emulsions, stabilized by 2% (w/v) whey protein isolate with varying concentrations of xanthan and quince seed gum. Quince seed gum resulted in emulsions with smaller low-shear viscosities and shear thinning capabilities compared to the same concentrations of xanthan. Quince seed gum emulsions with concentrations ≤ 0.1 (w/v), displayed rapid creaming due to bridging flocculation. Despite the difference in apparent viscosities, for gum concentrations b 0.2 (w/v), both gums demonstrated comparable stability with xanthan gum in general yielding marginally more stable emulsions. Gum concentrations N 0.3 (w/v) resulted in physically stable emulsions even after 5 months. Overall, quince seed gum displayed significant emulsification and stabilization properties.

Lentils are one of the cheapest and most nutritional protein sources for vegetarians. Our objective in this study was to evaluate the feasibility of using lentil flour as a raw material for the development of edible films and to investigate the effects of the glycerol concentration (C g 5 1, 1.5, and 2%) and process temperature (T p ; 70 and 90 8C) on the physical properties of these films. The films were characterized via their density; water solubility; thermal, morphological, and chemical characteristics; water vapor per-meability (WVP); and tensile and optical properties. The lentil flour films were highly transparent and had lower water solubility values yet similar WVPs and mechanical properties compared to most other biodegradable films. An increase in C g led to the formation of more flexible films with increased hydrophilicity. A T p of 90 8C resulted in yellower, more transparent films with increased stiffness compared to a T p of 70 8C. In this study, lentil flour was shown to be an ideal source for edible film production. V

Low-field bench top 1 H nuclear magnetic resonance (LF-NMR) relaxometry instruments have been increasingly popular as analytical tools for engineering research. Magnetic resonance imaging, which is a more advanced approach to NMR technology, provides the researcher with images of the internal structure without any disruption to the sample and has been commonly used in medical applications in analysis of soft tissue. The non-invasive and non-destructive nature coupled with the high discriminative power of LF-NMR and MRI, makes them invaluable tools of analysis for a wide range of applications in food science. This review covers the basic concept behind NMR/MRI technology and discusses some of its most commonly used food applications. The review addresses the food scientist with no prior knowledge of NMR/MRI and aims to supply the reader with both the theory of the method and its fundamentals, as well as the practical uses in scientific research and industrial applications.