Gıda Mühendisliği Bölümü Koleksiyonu

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https://hdl.handle.net/20.500.12428/2651

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The effect of simulated vibration frequency on the physico-mechanical and physicochemical properties of peach during transportation
(Elsevier Ltd., 2021) Dağdelen, Çiğdem; Aday, Mehmet Seçkin
Loss in fresh fruit and vegetables during transportation occurs mainly due to their susceptibility to mechanical damage. The quality loss caused by this damage depends on the shock and vibration frequencies. In this study, the effect of different vibration frequencies (5 Hz, 10 Hz, and 15 Hz) on the physico-mechanical and physico-chemical properties of peach was investigated. The parameters such as energy absorption, mechanical hysteresis, and deformation volume were increased whereas mean geometric diameter, surface area, volume, degree of elasticity, deformation energy, and modulus of elasticity were decreased. Regarding physicochemical properties, pH and total soluble solid parameters increased whereas lightness (L*) value of peach decreased. The highest level of damage and mold growth were observed on the peach treated with 15 Hz frequency followed by 10 Hz and 5 Hz, respectively. The effect of all the frequencies on the physico-mechanical and physico-chemical properties of peach was statistically different. The results indicated that the increase in the vibration frequency causes higher mechanical damage in peach.
Optimization of pretreatment and enzymatic hydrolysis conditions of tomato pomace for production of alcohols and esters by Kluyveromyces marxianus
(Elsevier Ltd., 2021) Kılmanoğlu, Hilal; İşleten Hoşoğlu, Müge; Güneşer, Onur; Karagül-Yüceer, Yonca
Tomato pomace (TP) is generated as a natural by product in a significant amount in the tomato processing industry, and it is a good source of lignocelluloses to produce some high-value products from fermentable sugars (FS). The present study was performed to produce FS by using either ultrasound-assisted dilute acid (UADA) or heat-treated dilute acid (HTDA) pretreatments of TP followed by enzymatic hydrolysis (EH). When HTDA and UADA were compared in terms of FS (g/L) concentration, HTDA pretreatment generally produced more FS content than UADA. The optimum conditions for HTDA pretreatment were the application of 2.5% H2SO4, 10% (w/v) solution of TP, and heating at 121 °C for 6 min, which yielded 31 g/L FS concentration. Beside the optimized conditions for EH of HTDA, pretreated TP required 1.5% of enzyme concentration and 6 h of hydrolysis time. In conclusion, the most abundant volatile organic compounds (VOCs) produced by K. marxianus in final tomato pomace hydrolysate (TPH) were isoamyl alcohol, phenyl ethyl alcohol, ethyl acetate and phenyl ethyl acetate in a 5-L bioreactor. Nine descriptive sensory terms were developed to characterize fermented TPH. The rose and sweet floral aromas were defined as aroma characteristics for TPH fermented by K. marxianus.
Soğuk Baskı Yöntemiyle Üretilmiş Greyfurt Çekirdek Yağındaki Acılığın Yıkama/Ekstraksiyon Teknikleriyle Giderilmesi
(Sidas Medya A.S., 2021) Deviren, Ayten; Ok, Selçuk; Yılmaz, Emin
In this study, different extraction and washing techniques used to remove the bitterness of grapefruit seed oil produced by cold pressing technique were compared. Some physico-chemical properties, oil components and sensory properties of the treated samples were determined. While the free fatty acidities of oils decreased with the treatments, there was a slight increase in the peroxide values of oils. As a result of the treatments, the ratio of total unsaturated fatty acids, tocopherol, and phytosterol concentrations decreased significantly (p<0.05). It is thought that these minor components, which have high nutritional value, leaked into the solvent phase. Naringin, which has a very bitter taste, was measured as 102.6 mg/kg in the control sample and reduced to 74.8 mg/kg by caustic washing and 32.3 mg/kg by extraction with ethanol. Similarly, neohesperidin, which has also a bitter taste, was completely removed from oils by these two treatments. Sensory score of bitterness was determined as 9.8 in the control sample, and it was reduced to 5.4 with caustic washing, and 2.6 with ethanol extraction. Similarly, raw vegetables, astringency, menthol and throat burning scores were also reduced with treatments. As a result, it was observed that the ethanol extraction technique was successful in removing the bitterness of oils.
MİKRODALGA DESTEKLİ HİDRODİSTİLASYON YÖNTEMİYLE ELDE EDİLEN PELARGONIUM GRAVEOLENS (ITIR) ESANSİYEL YAĞININ KARAKTERİSTİK BAZI ÖZELLİKLERİ
(Gıda Teknolojisi Derneği, 2021) Aydınlık, Pelin; Karagül Yüceer, Yonca
Bu çalışmada Pelargonium graveolens’den (ıtır) elde edilen esansiyel yağın karakteristik özellikleri incelenerek doğal katkı maddesi olarak elma suyunda kullanılabilirliği araştırılmıştır. Esansiyel yağ üretiminde mikrodalga destekli hidrodistilasyon yöntemi kullanılmış ve %1.75 verimle esansiyel yağ üretimi gerçekleştirilmiştir. Uçucu bileşenlerin tanımlanması amacıyla gaz kromatografisi kütle spektrometresi kullanılmıştır. Itır esansiyel yağının temel uçucu bileşenleri sitronelil format, izomenton, linalol, sitronelol ve geraniol olarak belirlenmiştir. Esansiyel yağın antioksidan aktivitesi 0.54 mM troloks/mL yağ bulunmuştur. Esansiyel yağın antibakteriyel etkisinin Escherichia coli’ye kıyasla Staphylococcus aureus üzerine daha fazla olduğu saptanmıştır. Itır esansiyel yağı ilave edilmiş elma suyunun mikrobiyel yükünde depolama boyunca düşüş olduğu belirlenmiştir. Ayrıca esansiyel yağ ilave edilen elma suyunun duyusal özellikler bakımından da kabul edilebilir olduğu tüketici testiyle ortaya koyulmuştur.
TİRE ÇAMUR PEYNİRİNİN BAZI FİZİKOKİMYASAL VE DUYUSAL ÖZELLİKLERİ
(2021) Karaalioğlu, Onur; Günay, Ezgi; Karagül Yüceer, Yonca
Bu çalışmanın amacı, İzmir’in Tire ilçesinde geleneksel olarak üretimi gerçekleştirilen Tire Çamur peyniri’nin bazı fizikokimyasal ve duyusal özelliklerinin belirlenmesidir. Bu çalışma kapsamında analizleri gerçekleştirilen Tire Çamur peyniri örnekleri arasında bileşim bakımından önemli farklılıklar olduğu saptanmıştır. Gaz kromatografisi-kütle spektrometrisi (GC-MS) vasıtasıyla gerçekleştirilen kromatografik analizlerde toplam 29 adet uçucu bileşen tespit edilmiştir. Duyusal değerlendirmeler sonucunda ise pişmiş, peynir altı suyu, kremamsı, fermente ve sütümsü yoğun olarak algılanan aromatikler olarak belirlenmiştir. Elde edilen veriler kapsamında, ürünün endüstriyel boyutlarda üretim standardizasyonunun sağlanmasıyla birlikte tüketiciler için ürünün kaynağını gösteren coğrafi işaret alınmasının; üreticiye, üretildiği bölgeye ve ülkemize önemli ekonomik katkı ve katma değer sağlama potansiyeline sahip olacağı düşünülmüştür.
Çanakkale bölgesinden alınan midye ve deniz suyu örneklerinin mikrobiyolojik kalitelerinin belirlenmesi
(2021) Tosun, Melike Nur; Taylan Yalçın, Gizem; Zorba, Nükhet Nilüfer
Bu çalışmada Çanakkale bölgesinde belirlenen 9 farklı istasyondan toplanan 536 midye örneğinin ve her istasyondan alınan deniz suyunun mikrobiyolojik kalitesi belirlenmiştir. Midye örneklerinin toplam mezofilik aerobik bakteri yükünün en yüksek Merkez İskele istasyonunda (3.56 log kob/g) olduğu belirlenmiştir. En yüksek E. coli varlığı ise Gelibolu istasyonunda (1.99 log kob/g) saptanmıştır. Midyelerin mikrobiyel yüklerinin toplandıkları istasyonlar arasında istatistiksel anlamda farklı olmadığı (P>0.05) görülmüştür. Midyelerin toplam mezofilik aerobik bakteri sayısı ile toplandıkları deniz suyunun toplam mezofilik aerobik bakteri sayısı arasında pozitif yönde korelasyon tespit edilmiştir (P<0.05). Gelibolu ve Lapseki istasyonlarındaki mikrobiyel yükün diğer istasyonlara göre daha yüksek olduğu saptanmıştır. Genel olarak değerlendirildiğinde Gelibolu ve Lapseki bölgesi haricinde Çanakkale boğazının farklı noktalarından alınan midyelerin mikrobiyel kalitesinin yasal sınırlar içerisinde olduğu belirlenmiştir.
Yayıkaltı içeceğinin fizikokimyasal ve duyusal özellikleri ile uçucu bileşenlerinin belirlenmesi
(2021) Öğe, Çisem; Karagül Yüceer, Yonca
Bu çalışmada yayıkaltı suyunun farklı mikroorganizmalarla fermantasyonu ile üretilen içeceklerin karakteristik bazı özelliklerinin belirlenmesi amaçlanmıştır. Toz halindeki yayıkaltının %10’luk çözeltisi ile belirli oranlarda (% 0, 25, 50, 75, 100) çiğ süt karışımına ısıl işlem uygulandıktan sonra örneklere L. acidophilus (LA) kültürü ve L. acidophilus, Bifidobacteria ile S. thermophilus karışık kültürü (ABT) ilave edilerek 37°C’de, yaklaşık 4.8 pH’ya kadar inkübe edilmiştir. Ürünlerin fizikokimyasal ve duyusal özellikleri ve uçucu bileşenleri depolama süresince belirlenmiştir. İçeceklerde yayıkaltı suyu oranı azaldıkça yağ, kurumadde ve protein oranları artmıştır. Örneklerde uçucu bileşenler gaz kromatografisi kütle spektrometrisi kullanılarak belirlenmiştir. Tüm örneklerde belirlenen uçucu bileşikler aseton, 2,3-butandion, asetoin, toluen, 2-heptanon, limonen, ökaliptol, asetik asit ve butanoik asit olmuştur. Yayıkaltı içeceklerinde pişmiş, kremamsı, süthane/sütümsü, fermente, karton, yosun, sabunsu, depo, tatlı, tuzlu, buruk ve acı terimleri duyusal değerlendirmeler sonucunda belirlenmiştir.
Kitosan bazlı etil pirüvat filmlerin fizikokimyasal, antioksidan, antimikrobiyal ve anti-quorum sensing özelliklerinin belirlenmesi
(2021) Kaya, Burcu; Zorba, Nükhet Nilüfer; Caner, Cengiz
Bu çalışmada kitosan film formülasyonuna iki farklı (%1 ve %3) konsantrasyonda etil pirüvat ilave edilerek, çevre dostu bir ambalaj materyali geliştirilmesi amaçlanmıştır. Bu kapsamda hazırlanan film örneklerinin nem, suda çözünürlük, görünür yoğunluk, renk, biyobozunurluk, kimyasallara karşı direnç özellikleri belirlenerek, filmlerin yüzey morfolojisi SEM, fonksiyonel grupları ise FTIR ile karakterize edilmiştir. Ayrıca film örneklerinin antimikrobiyal ve anti-quorum sensing aktivitesi disk difüzyon yöntemi ile belirlenmiştir. Sonuç olarak formülasyona etil pirüvat eklenmesiyle kitosan filmin nem içeriği, görünür yoğunluğu, biyobozunurluğu ve antioksidan aktivitesi artmıştır. SEM görüntüleri incelendiğinde ise etil pirüvatın, kitosan filmlerde gözenekli yapı oluşumuna neden olduğu gözlemlenmiştir. Film örnekleri Escherichia coli O157:H7, Bacillus cereus, Staphyloccocus aureus, Alternaria arborescens, Aspergillus flavus, Penicillium digitatum, Penicillium citrinum ve Penicillum expansum suşlarına karşı antimikrobiyal etki göstermiştir. Buna ek olarak tüm film örneklerinin anti-quorum sensing aktivite gösterdiği tespit edilmiştir. Elde edilen verilere göre özellikle CS-EP1 filminin, doğa dostu alternatif gıda ambalajı olarak kullanılabileceği belirlenmiştir.
Characterization of aroma-active compounds, sensory properties, and proteolysis in Ezine cheese
(Elsevier Science Inc, 2009) Karagül Yüceer, Yonca; Tuncel, Barış; Güneşer, Onur; Engin, Burcu; İşleten, Müge; Yaşar, Kurban; Mendeş, Mehmet
Ezine cheese is a white pickled cheese ripened in tin-plate containers for at least 8 mo. A mixture of milk from goat, sheep, and cow is used to make Ezine cheese. Ezine cheese has geographical indication status. The purposes of this study were to determine and compare the changes in basic composition, aroma, and sensory characteristics, and proteolytic activity of Ezine cheese stored in tinplate containers and plastic vacuum packages during storage. Aroma-active compounds were determined by thermal desorption gas chromatography olfactometry. To evaluate the proteolytic activity, casein and nitrogen fractions were determined. The results indicated that compounds identified at high intensities were dimethyl sulfide, ethyl butyrate, hexanal, ethyl pentanoate, (Z)-4-heptenal, 1-octen-3-one, acetic acid, butyric acid, and p-cresol. Characteristic descriptive terms were cooked, whey, creamy, animal-like, sour, and salty. The level of proteolysis increased in Ezine cheese during storage. Ezine cheese can be ripened in small-size packaging after 3 mo of storage. Approximately 6 mo is sufficient to produce the characteristic properties of Ezine cheese.
Sensory characteristics of Ezine cheese
(Wiley, 2007) Karagül Yüceer, Yonca; İşleten, Müge; Uysal Pala, Çiğdem
Ezine cheese is a full-fat, white pickled cheese ripened in tinplate containers. A mixture of milks from goat, sheep and cow is used to make Ezine cheese. It has its own characteristic taste and aroma that differ from other white cheeses. In this study, the chemical composition and sensory attributes of Ezine cheese were characterized. A descriptive sensory evaluation technique was used to determine flavor and texture characteristics. Representative Ezine cheeses (22) were provided by local producers. A highly trained (n = 9) panel generated the descriptive terms and identified the references. Fourteen flavors and 10 texture terms were developed to describe Ezine cheese flavor and texture. Some characteristic flavor and taste descriptors for Ezine cheese were free fatty acids, cooked, creamy, whey-like, goaty, salty and sour. Cheese texture was evaluated using hand, mouth and residual techniques. Texture analysis indicated that Ezine cheese had soft and semi-hard texture properties. In general, most of the Ezine cheeses showed similarities in terms of hand firmness, mouth firmness, fracturability and number of particles attributes.
Comparative analysis of essential oil oleogels containing beeswax and sunflower wax with petrolatum gels
(Wiley, 2024) Çokay, Hatice; Çelebi Uzkuç, N. Merve; Karagül Yüceer, Yonca; Öğütcü, Mustafa
In this study, three different oil (black seed, St. John's Wort, and grape seed oils [GSO]) oleogels, which are especially used in complementary medicine, were produced with natural waxes (sunflower and beeswax [BW]). The physicochemical, textural, thermal, and structural features and volatile composition of the oleogels were determined and compared with commercial petrolatum gels (control sample). The sunflower and BW gels had a higher melting point than the petrolatum gels. Particularly, the firmness values of the fresh sunflower and BW oleogels were close to the petrolatum gels, except for the BW-based St John's Wort and GSO gels. The firmness and stickiness values of the oleogels and the control samples increased in relation to the storage period. The increase in firmness value was less in the sunflower wax than in the BW and control samples. All sunflower, BW and petrolatum gels exhibited the beta ' form. Volatile component data showed that different waxes have different volatile adsorption capacities. As a result, natural wax oleogels produced with various essential oils could be an alternative to similar products used in the cosmetics, pharmacology, and food supplement industries, which are already commercially available.Practical applications: (Oleogels have become a popular technique for structuring oils in recent years. In this way, oleogels are considered an alternative to solid fat such as margarine, butter, and shortening and an oil-restricting agent against oil leakage in oil-based foods. Consumers establish a close relationship between their own health and the foods they consume and the cosmetics they use. This situation has led to an increasing interest in natural products. Essential oils (EOs) are used in many fields, ranging from cosmetics to complementary medicine. In this context, essential oleogels produced with natural waxes were compared with the commercial products, revealing their potential for use in both cosmetic and food supplements. EO-oleogels represent a new approach to the oleogel product range with high commercialization potential for related industries.) Graphical Abstract: The textural and structural properties of the essential oil oleogels prepared with beeswax and sunflower wax were almost similar to their commercial counterparts such as petrolatum. image
Characterisation of aroma-active compounds, chemical and sensory properties of acid-coagulated cheese: Circassian cheese
(Wiley, 2011) Güneşer, Onur; Karagül Yüceer, Yonca
The objectives of this study were to determine basic composition, aroma and sensory characteristics of Circassian cheese. Seven Circassian cheeses were provided by local producers. Aroma compounds were extracted by using solid-phase microextraction procedure and determined by gas chromatography-olfactometry system. Water-soluble, trichloroacetic acid-soluble and phosphotungstic acid-soluble nitrogen fractions ranged between 2.30-29.35%, 2.48-9.96% and 3.33-6.26%, respectively. Diacetyl, butyric acid, 2-acetyl-1-pyrroline, 1-octen-3-one and methional were identified at high intensities in cheeses. In addition, 'cooked', 'whey', 'creamy' and 'fermented' were defined as characteristic flavour terms for Circassian cheeses.
Biosynthesis of eight-carbon volatiles from tomato and pepper pomaces by fungi: Trichoderma atroviride and Aspergillus sojae
(Soc Bioscience Bioengineering Japan, 2017) Güneşer, Onur; Karagül Yüceer, Yonca
The aim of this study was to investigate the possibility of using tomato and red pepper pomaces for the production eight-carbon volatiles by Trichoderma atroviride and Aspergillus sojae. The fermentation of tomato and pepper pomace based media by both moulds was conducted in shake flasks and bioreactors. Microbial growth behaviours and fermentation abilities of T. atroviride and A. sojae under both fermentation conditions were followed by microbial counting. The production of flavours from tomato and pepper pomaces by fungal metabolism was determined by gas chromatography olfactometry, gas chromatography-mass spectrometry and sensory analysis. The results showed that T. atroviride grew faster than A. sojae, and the survival of T. atroviride in the tomato pomace was longer than that of A. sojae. However, T. atroviride grew slower than A. sojae in the pepper pomace. Eight-carbon flavour compounds, including (Z)-1,5-octadien-3-ol, 1-octen-3-ol, (E)-2-octenal and (E)-2-octenol, were produced by T. atroviride and A. sojae from the tomato and pepper pomaces. The highest production levels (265.55 +/- 2.79 and 187.47 +/- 0.92 mu g kg(-1)) were observed for 1-octen-3-ol in the tomato fermentation by T. atroviride and A. sojae, respectively. The relationships between volatile compounds and their flavour characteristics in tomato and pepper pomaces were analysed using principal component analysis. (C) 2017, The Society for Biotechnology, Japan. All rights reserved.
Physicochemical, textural, volatile, and sensory profiles of traditional Sepet cheese
(Elsevier Science Inc, 2011) Ercan, D.; Korel, F.; Karagül Yüceer, Yonca; Kınık, O.
Characterization of traditional cheeses is important for the protection of diversity of tradition and contributing baseline data for further research and quality control. Sepet cheese is a traditional cheese and specific to the Aegean region of Turkey. In this study, 52 Sepet cheese samples were analyzed to characterize the physicochemical, textural, volatile compounds, and sensory profiles. The changes in the physicochemical and volatile compositions were investigated during production and ripening periods. The average dry matter (DM; 55.16%), fat-in-DM (45.80%), protein (29.18%), salt-in-DM (12.88%), water activity (0.83), pH (5.50), titratable acidity (1.69%), ripening and lipolysis indices (11.06 and 6.36), firmness (212.20 N), springiness (0.62), cohesiveness (0.57), adhesiveness (0.48 Nmm), and chewiness (66.87 N) values of Sepet cheese samples were determined. Hexanoic, octanoic, decanoic, and butyric acids, which were responsible for the cheesy, waxy, goaty odors, were the most abundant volatile compounds in these cheeses. Most of the volatile compounds increased significantly during production and ripening. Significant changes in most of the physicochemical characteristics were observed up to the third month of ripening. As a result of the descriptive sensory analysis, Sepet cheeses were described with descriptors such as free fatty acid, animal like, sulfurous, creamy, cooked, and whey, and aromatics with high salty basic taste.
Bioflavour production from tomato and pepper pomaces by Kluyveromyces marxianus and Debaryomyces hansenii
(Springer, 2015) Güneşer, Onur; Demirkol, Aslı; Karagül Yüceer, Yonca; Özmen Togay, Sine; İşleten Hoşoğlu, Müge; Elibol, Murat
Bioflavours are called natural flavour and/or fragrance compounds which are produced using metabolic pathway of the microorganism and/or plant cells or their enzyme systems with bioengineering approaches. The aim of this study was to investigate bioflavour production from tomato and red pepper pomaces by Kluyveromyces marxianus and Debaryomyces hansenii. Obtained specific growth rates of K. marxianus and D. hansenii in tomato pomace were 0.081/h and 0.177/h, respectively. The bioflavour profile differed between the yeasts. Both yeasts can produce esters and alcohols such as phenyl ethyl alcohol, isoamyl alcohol, isoamyl acetate, phenyl ethyl acetate and isovaleric acid. Tarhana and rose were descriptive flavour terms for tomato and pepper pomaces fermented by K. marxianus, respectively. Tomato pomace fermented by D. hansenii had the most intense green bean flavour while fermented vegetable and storage/yeast were defined as characteristic flavour terms for pepper pomaces fermented by D. hansenii.
Chemical composition, antimicrobial, antioxidant and anthocyanin activities of mosses (Cinclidotus fontinaloides (Hedw.) P.Beauv. and Palustriella commutata (Hedw.) Ochyra) gathered from Turkey
(Taylor & Francis Ltd, 2017) Tonguç Yayıntaş, Özlem; Alpaslan, Duygu; Karagül Yüceer, Yonca; Yılmaz, Selehattin; Şahiner, Nurettin
Cinclidotus fontinaloides (Hedw.) P. Beauv. and Palustriella commutata (Hedw.) Ochyra were used in this study. The chemical composition of mosses in the ethanol and water extract was determined using GC-MS and FT-IR. Antioxidant activities of moss extracts were tested by total phenol and ABTS methods. Trolox equivalent value (TEAC) of mosses was calculated as 26 +/- 0.32 and 10 +/- 0.22 mg/g. The amounts of the flavonoid compounds were calculated as mg gallic acid. Gallic acid equivalent value of mosses was calculated as 587 +/- 0.55 and 496 +/- 0.22 mg/g. The extracts antimicrobial activity was tested against Escherichia coli (ATCC 8739), Bacillus subtilis (ATCC 6633), Staphylococcus aureus (ATCC 6538), Pseudomonas aeruginosa (ATCC 10145) and Candida albicans (ATCC 10231). Significant antibacterial effect was observed for C. fontinaloides and P. commutata in ethanol extract. Total anthocyanin activities of C. fontinaloides and P. commutata were determined as 50 +/- 0.17 and 144 +/- 0.33 mg/L.
Milk hydrogels as nutrient media and survival rate enhancer under cryogenic conditions for different microorganisms
(Springer, 2016) Alpaslan, Duygu; Şahiner, Mehtap; Yüceer, Yonca; Akçalı, Alper ; Aktaş, Nahit; Şahiner, Nurettin
Milk-containing hydrogels from 2-hydroxyethylmethacrylate (HEMA) and acrylamide (AAm) as p(HEMA)/whole milk, p(HEMA)/semi-skimmed milk, p(HEMA)/skimmed milk, p(AAm)/whole milk, p(AAm)/semi-skimmed milk, p(AAm)/skimmed milk were synthesized by conventional redox polymerization technique using corresponding monomers and milk as solvents. The aim of this study was to investigate the use of milk-containing hydrogels as a nutritional medium, e.g., up 124 days for enhanced or longer cryostorage media for various microorganisms such as Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis, and fungi, Aspergillus niger, Aspergillus fumigates, and a yeast Candida albicans. It was shown that milk hydrogels can be used as nutritional media for the growth of these microorganisms, whereas the control hydrogels cannot be used for the same purpose. The survival rates of p(HEMA)/whole milk and p(AAm)/whole milk hydrogels for E. coli after 124 days were found to exceed those of the control p(HEMA) and p(AAm) hydrogels by 109- and 56-fold, respectively. Moreover, the survival rates for S. aureus were calculated to be 42 and 24 times longer than the controls, as the hydrogels containing whole milk were used as storage media in comparison with the bare hydrogels. Furthermore, the cryogenic survival rates of p(HEMA)/whole milk and p(AAM)/whole milk were compared with whole milk and nutrient broth used as a control, and calculated to be 67-, 171-, 35-, and 89-fold greater, respectively, than those of the control samples for E. coli.
Effect of ultraviolet light on water- and fat-soluble vitamins in cow and goat milk
(Elsevier Science Inc, 2012) Güneşer, Onur; Karagül Yüceer, Yonca
The objective of this study was to investigate and compare the effects of UV light and heat treatment on vitamins A, B-2, C, and E in cow and goat milk. Vitamins were analyzed by reverse-phase high-pressure liquid chromatography. Ultraviolet and pasteurization treatments caused loss in vitamin C in milk. Pasteurization did not have any significant effect on vitamin B-2. However, UV light treatment decreased the amount of vitamin B2 after several passes of milk through the UV system. In addition, UV light treatment decreased the amount of vitamins A and E. Vitamins C and E are more sensitive to UV light. UV light sensitivities of vitamins were C > E > A > B-2. These results show that UV light treatment decreases the vitamin content in milk. Also, the number of passes through the UV system and the initial amount of vitamins in milk are important factors affecting vitamin levels.
Changes in milk fatty acid composition of goats during lactation in a semi-intensive production system
(Archiv Fur Tierzucht, 2009) Ataşoğlu, Cengiz; Uysal Pala, Çiğdem; Karagül Yüceer, Yonca
This study aimed at investigating changes in the fatty acid (FA) profile and conjugated linoleic acid (CLA) concentration of milk fat during lactation from goats managed in a semi-intensive production system, which consisted of grazing on a woody and herbaceous pasture with the supplementation of mixed concentrate and vetch hay. A total of 21 lactating goats were used. Milk samples were collected at different periods (25 April, 29 June, 25 August and 4 October) during lactation and analysed for their chemical composition and FA profile. The most abundant FA in the milk fat of goats was palmitic (06:0) acid, followed by oleic (C18:1 n-9), stearic (C18:0), capric (C10:0) and myristic (04:0) acids. These acids accounted for about 88% of the total milk FA of goats in all sampling periods. The two medium chain FA; capric (P=0.0001) and lauric (C12:0; P=0.0014) acid were affected by the sampling period, whereas myristic (P=0.4469) and palmitic (P=0.4418) acids did not change. Stearic (P=0.0128), oleic (P=0.0001), linoleic (C18:2; P=0.0088) and linolenic (C18:3; P=0.0001) acids also exhibited significant variations between the sampling periods. However, the CLA (C18:2 c9, t11 and C18:2 00, c12) contents of milk fat did not change during the entire study regardless of the sampling period (P=0.2448). Milk fatty acid composition of goats, which meet a major part of their nutrient requirements through grazing or browsing in a natural pasture, shows a seasonal variation with milk fat in summer representing a better fatty acid profile for product quality.
Sensory properties of drinkable yogurt made from milk of different goat breeds
(Wiley, 2006) Uysal Pala, Çiğdem; Karagül Yüceer, Yonca; Pala, A.; Savaş, Türker
Drinkable yogurts made from different goat breed milk and made with normal and probiotic cultures were evaluated for their sensory characteristics. Milk of Turkish Saanen, Maltese and Turkish Hair goats obtained during the beginning, middle and end of lactations were used to produce drinkable yogurt. Using descriptive sensory analysis technique, common terms were developed as goaty, creamy, fermented, cooked, throat burn, sweet, salty, sour and astringent. Breeds, lactation periods and using regular and probiotic types of starter cultures affected the sensory characteristics of drinkable yogurts. Drinkable yogurts made by cow milk had weaker intensities of flavor attributes including goaty, creamy, throat burn and salty than that made by goat milks of the three breeds. Drinkable yogurts made from Turkish Saanen breed had more goaty flavor than those made from Turkish Hair and Maltese goat breeds. The products made by milk provided at the end of lactation period had the highest intensities of goaty flavor. In addition, the intensities of goaty, creamy and cooked flavors in the products made by regular yogurt cultures were higher than those of drinkable yogurts with probiotic cultures.

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