Emin Yılmaz

Characterization of Hazelnut Oil Oleogels Prepared with Sunflower and Carnauba Waxes

In this study, hazelnut oil oleogels prepared with sunflower wax and carnauba wax were analyzed and compared with a commercial shortening. Oil binding capacities of sunflower wax oleogels were higher than 99%, while carnauba wax had a maximum value of 97.6% for 10% addition level. At 3% addition level of carnauba wax, no gel developed. The crystal formation time of sunflower wax was shorter. Although the highest (8.5%) solid fat content was observed in the 10% carnauba wax containing oleogel (HC10) sample, it was 30.4% in the commercial shortening sample at 20°C. The peak melting temperature of commercial shortening was 52.3°C, and among all organogels, sunflower wax oleogel at 3% addition level had the closest value (58.4°C). The melting enthalpies of the oleogels ranged from 4.3 to 20.3 J/g, while it was 10.9 J/g for the commercial shortening sample. The firmness and stickiness values in the oleogel samples were lower than that of commercial shortening sample. On the other hand, there was no significant change of firmness and stickiness during storage, indicating good stability (p ≤ 0.001). Especially the sunflower wax oleogels were very homogenous and smooth in structure. The polarized light microscopy pictures revealed needle-like crystals for sunflower wax and aggregate-like crystals for carnauba wax oleogels. The x-ray diffraction measurements of the crystals showed the β´ types of the polymorphic structures. Furthermore, the oleogels were very stable against oxidation during the storage period. Hazelnut oil organogels prepared with sunflower wax can be good source material for shortening or margarine-like products.

Oleogels as spreadable fat and butter alternatives: sensory description and consumer perception

Table spreads are one of the fundamental ingredients of human diets. Generally, butter and margarine are the most preferred spread products among others. Moreover, these products have some disadvantages such as high saturated fatty acids contents and the presence of trans fatty acids. In this study, virgin olive oil and hazelnut oil oleogels were prepared with beeswax and sunflower wax, while the hazelnut oil oleogels were aromatized with diacetyl. For the reason stated above, the first purpose of this study was to test the sensory properties and consumer acceptance of virgin olive oil when prepared as a spreadable fat in oleogel form. The second purpose was to determine how the hazelnut oil oleogels would be received as a butter alternative by the sensory and consumer tests as well. The results revealed that both types of oleogels are structurally and thermally suitable as alternative products. For the first time in the literature, these oleogels were described by a panel with thirteen sensory definition terms (hardness, spreadability, liquefaction, grassy, milky, rancid, fatty, sweet, salty, waxy, grittiness, cooling and mouth coating). Hedonic attributes (appearance, odor, flavor, spreadability) tested by the consumers proved that these oleogel products have potential as spread and/or butter alternatives. In the consumer survey study, one of the striking results indicated that more than 50% of the consumers would buy or try once, then decide to buy the oleogel products. In conclusion, these oleogels can be used as spreads or butter alternatives.

Assessment of Thermal and Textural Characteristics and Consumer Preferences of Lemon and Strawberry Flavored Fish Oil Organogels

In this study, strawberry and lemon flavored fish oil organogels (FOO) were prepared with beeswax as the organogelator. The physical, thermal and textural characteristics as well as the consumer preferences of the flavored organogels were determined in comparison with fish oil and FOO containing no flavor. Furthermore, the stability of the organogels was evaluated during 90 day storage at 4°C. The results revealed that, structurally stable fish oil organogels as spreadable products might be formed and that flavoring of the gels enhances consumer preference. Thus, flavoring of fish oil organogels could be a challenge in increasing the consumption of fish oil.

Extraction and Functional Properties of Proteins from Pre-roasted and Enzyme Treated Poppyseed (Papaver somniferum L.) Press Cakes

In this study, proteins of the defatted meals obtained from cold-pressed poppyseed previously treated (pre-roasting and enzyme against control) were extracted and their compositional and functional properties were determined. Saline-alkaline extraction (pH 11-12, and 0.2-0.6 M NaCI) and isoelectric point (pH 4.0-5.5) precipitation technique showed that seed pre-roasting enhances protein yield while enzyme treatment reduces it. There were 7 bands on SDS-PAGE, and enzyme treated samples were weaker than control. While enzyme treatment decreased denaturation temperatures (T(d)), roasting enhanced the enthalpy change (ΔH) values. Pre-treatments caused a decrease in protein least gelling concentration (LGC) values. Water and oil holding capacities (WHC and OHC) were found lower in enzyme treated and higher in preroasted samples. Similar effects were also determined for emulsifying activity (EA) and emulsion stability (ES) values. While foaming capacity (FC) in treated samples decreased, foam stability (FS) increased oppositely. In conclusion, poppyseed meals can be nutritionally good source for diet protein, and a limited pre-roasting can be very beneficial for enhanced protein extraction yield and desirable functional properties.

Biotechnological production of prostaglandin

Prostaglandins (PGs) are the oxidation products of PG endoperoxide (PGH) synthase and other tissue enzymes. They occur in a tissue-specific manner and act as local hormones. Biotechnological production of PGs has been of interest, but not yet fully established. Biological tissues have been used as PG sources, but this disturbs ecological balance, and the cost of production is very high for commercial purposes. On the other hand, various microorganisms have been shown to synthesize them de novo, or biotransform precursors to active molecules, but these processes have not been further evaluated. Using mammalian enzymes in free or immobilized form is a promising new approach to synthesize PG from fatty acid substrates. Rapid enzyme inactivation during the catalysis is the main problem to be solved. Optimization of factors in the reactions and the design of special reactors that will allow removal of products continuously from the reaction medium without affecting enzyme activity need immediate attention from researchers and the pharmaceutical industry.

Sensory evaluation and consumer perception of some commercial green table olives

Purpose – The objective of this study is to evaluate the physico‐chemical and sensorial characteristics of some commercial green table olives. Also, it seeks to elaborate the sensorial background of consumer preferences of different green table olives.Design/methodology/approach – Four green table olive samples (Celebi, Domat, Kaba, and Ayvalik) commonly consumed in Turkey were chosen and collected from a local producer. Dimensional measures, salt content, pH value, oil content, titrable acidity, L value, a* value, b* value and texture of samples were assessed by the AOAC methods. A panel described and measured the appearance (greenness, yellowness, globeness), aroma (fresh olive, vinegary, soapy, musty), flavour (sour, salty, bitter, hay, oily) and texture properties (firmness, flesh/stone adherence, fibrousness, watery). In addition, 50 consumers evaluated hedonic values.Findings – The salt content, pH value, oil content, titrable acidity, L value, a* value, b* value and texture of samples were found to...

Cold pressed versus solvent extracted lemon (Citrus limon L.) seed oils: yield and properties

During the processing of lemon fruit, a large quantity of seeds is produced as a by-product. These seeds contain valuable components; therefore, required to be evaluated. This study aimed to compare the cold pressed with hexane-extracted lemon seed oils and determine their physicochemical and thermal properties. Cold pressing yielded significantly lower oil (36.84%) than hexane extraction (71.29%). In addition, the concentrations of free fatty acids, peroxides, and p-anisidine were lower in the cold pressed oil. Cold pressed oil showed higher total phenolics, α-tocopherol and antioxidant capacity. The major fatty acids found in the cold pressed oil were linoleic and palmitic acids, whereas β-sitosterol and campesterol were the dominant sterols. The crystallization and melting temperatures and enthalpies were also elucidated. In conclusion, this study proved that high quality of lemon seed oils can be produced by the cold pressing technique; this oil can be used in industries such as the food, cosmetic or chemical industries.

Structure and Stability of Fish Oil Organogels Prepared with Sunflower Wax and Monoglyceride

The aims of this study were to develop fish oil (FO) organogels with sunflower wax (SW) and monoglyceride (MG), and compare them with a commercial margarine (CM). The organogels were stored at 4 and 20°C for 90 days and their storage stability was investigated. The color values, oil binding capacity, crystal formation time, solid fat content, thermal properties and crystal structures of the organogels were measured. During storage, their textural properties and peroxide values were monitored. The melting temperature of the MG organogels was found similar to that of the CM sample. Otherwise, the melting points of the MG gels were lower than those of the SW gels. Crystal morphology of the CM sample was found similar to MG gels by X-ray measurements. The firmness values of the SW organogels were higher than those of the MG gels. The peroxide values of all gels were within the legal limits.

Extraction and characterisation of lemon, orange and grapefruit seeds press cake proteins

The aim of this study was to characterise the proteins of lemon (Citrus limon var. Kutdiken), orange (Citrus sinensis var. Dortyol) and grapefruit (Citrus paradisivar. Beyaz) seeds extracted from their defatted press cakes. The press cakes were collected from the cold oil pressing of the seeds which were pre-treated by different techniques. Ultrasound-assisted alkaline (pH=9.0) extraction and isoelectric point (pH=4.0) precipitation procedure yielded around 34.47-80.95% proteins. The extracted seed proteins were in good quality for colour and antioxidant capacity. The extracted-lyophilised proteins were more soluble at pH 11-12 and below 2. The viscosity of the protein dispersions ranged from 3.67 to 25.70 cP. Sixteen amino acids were quantified in the samples, while asparagine, cysteine, hydroxyproline and tryptophan were absent. Thermal denaturation temperature and enthalpy change of denaturation were reported for the first time. The gel electrophoresis indicated four distinct protein bands at around 10...

Antimicrobial and functional properties of the proteins extracted from lemon, orange and grapefruit seeds press meals

The aim of this study was to determine the antimicrobial activities and functional properties of the proteins extracted from lemon (Citrus limon var. Kutdiken), orange (Citrus sinensis var. Dortyol...