Effect of food matrix and fermentation on angiotensin-converting enzyme inhibitory activity and ß-glucan release after in vitro digestion in oat-based products.

The aim of this study was to determine the effects of fermentation and food matrix on the ACE inhibitory activities of the peptides obtained after in vitro gastrointestinal digestion, protein profiles (SDS-PAGE) and ß-glucan amounts of oat products. Furthermore, the physicochemical and microbiological properties of fermented oat drinks and oat yogurt-like product obtained from oat fermentation were evaluated. Oat grains were mixed with a certain ratio of water 1:3 w/v (oat:water, yogurt consistency) and 1:5 w/v (oat:water, drink consistency), and this mixture was fermented with yogurt culture and probiotic Lactobacillus plantarum and fermented drinks and yogurt were produced. The results indicated that the fermented oat drink and the oat yogurt-like product had L. plantarum viability over 107 cfu/g. After the in vitro gastrointestinal digestion of the samples, the hydrolysis levels ranged from 57.70 % to 82.06 %.The hydrolysis level of the samples with fermented-drink consistency was significantly higher than the samples with yogurt consistency (p < 0.05).The SDS-PAGE profiles of the non-digested samples showed that the bands had molecular weights of 12-15 kDa and around 35 kDa. Bands whose molecular weights were around 35 kDA disappeared after gastric digestion. ACE inhibitory activities of the fractions composed of molecular weights of 2 kDa and 2-5 kDa obtained after in vitro gastrointestinal digestion of the oat samples were in the range of 46.93-65.91 %. The effect of fermentation on the ACE inhibitory activities of the peptide mixture with molecular weights between 2 and 5 kDa was not statistically significant, however, fermentation caused an increase in the ACE inhibitory activities of the peptide mixture with a molecular weight<2 kDa (p < 0.05). The ß-glucan amounts of fermented and non-fermented oat products were in the range of 0.57-1.28 %. The ß-glucan amounts detected after gastric digestion decreased considerably and ß-glucan could not be detected in the supernatant after gastrointestinal digestion. This indicated that ß-glucan did not solubilize in the supernatant (bioaccessible) and remained in the pellet. In conclusion, fermentation is a valuable process for releasing peptides with moderately high ACE inhibitory effects from the parent oat proteins.

Viability of Probiotics, Rheological and the Sensorial Properties of Probiotic Yogurts Fortified with Aqueous Extracts of Some Plants.

In this research, we aimed to evaluate the effects of various medicinal and aromatic plant aqueous extracts on physicochemical, rheological, sensorial properties of probiotic yogurts and the viability of yogurt bacteria and probiotic bacteria during the storage period. On the 28 day of storage, the maximum Bifidobacterium longum and Lacticaseibacillus casei counts were determined in thyme containing yogurt and mint and basil containing yogurt, respectively. On the 1st day of storage, the most favoured yogurt was garlic containing sample while on the 14th day, the control sample was the most favoured one. Hardness values were not showed statistically difference for all sample (p>0.05). Especially the garlic and mint yogurt samples were more liked in terms of sensory properties. Consequently, aqueous extracts of some plants such as garlic, basil and thyme have successfully used in probiotic yogurt production and all yogurt samples containing plants have the enough probiotic counts to show therapeutic effect on human health.

The effect of aqueous extracts of some plants on in vitro antioxidant and antidiabetic activity of probiotic yogurt.

In this study, aqueous extracts of some medicinal and aromatic plants (garlic, Turkish Oregano, rosemary, basil, and peppermint) were used in probiotic yogurt production to increase functionality of probiotic yogurt. The in vitro antidiabetic, antioxidant activity, total phenolic compound content and phenolic compounds of yogurts were evaluated during the 28 day of storage period. Yogurt sample with Turkish Oregano had the highest α-amylase and α-glucosidase inhibitory activity. A strong correlation was found between total phenolic compound content and antioxidant activity (r = 0.84) and between total phenolic compounds content and α-amylase inhibitory activity (r = 0.82). In conclusion, it can be said that the total phenolic compound content and in vitro antioxidant and antidiabetic activities of probiotic yogurt could be increased by adding aqueous extracts of some plants.

Determination of the microbial flora in traditional Izmir Tulum cheeses by Denaturing Gradient Gel Electrophoresis.

In this study, it was aimed to determine microbial flora members in three traditional Tulum cheeses (C1, C2 and C3) produced in different villages and settlement areas in Izmir, Turkey. For this purpose, culture depended and 16S rRNA based culture independent methods were used. According to the results of culture depended method, Lactococcus spp., Enterococcus spp., Staphylococcus spp., Lactobacillus spp., Pediococcus spp. and yeast-mold were detected in all samples at different levels. In order to determine and identify both of the culturable and non-culturable microorganisms, denaturing gradient gel electrophoresis (DGGE) method was used. DGGE results have shown that there were eight different dominant microorganisms (Streptococcus thermophilus, Lactococcus lactis subs. lactis, Streptococcus infantarius subs. infantarius, Lactobacillus gallinarum, Streptococcus equinus, Enterococcus faecalis, Enterococcus faecium, Lactococcus garvieae) in three regionally cheese samples. Further more, total bacterial loads were monitored with real-time PCR (qPCR) method. According to the results, 3.5 × 108, 3.8 × 108, 8.4 × 108 copy number of DNA was detected in C1, C2 and C3 cheese samples, respectively. This study is the first description for the dynamics of microbial composition of Izmir Tulum cheese after the production and brining processes.

Survival of Bifidobacterium longum and its effect on physicochemical properties and sensorial attributes of white brined cheese.

Survival of the probiotic adjunct culture Bifidobacterium longum and cheese starters during ripening of white brined cheese, effect of the probiotic culture on physicochemical properties and sensorial attributes of cheeses were investigated throughout 90 d of ripening. Bifidobacterium longum were able to survive at higher levels (>10(7 )cfu/g cheese) than the therapeutic minimum (10(6)-10(7 )cfu/g cheese) after 90 d and did not have any negative effect on the survival of Streptococcus spp. (including common cheese starters). Incorporation of the probiotic adjunct into white brined cheese and high levels of their survival rates during ripening had an insignificant effect on the composition of cheeses. Results indicated that white brined cheese is a suitable food matrix for the delivery of B. longum used in this study, and white brined cheeses with B. longum may be considered as a probiotic dairy product.

Immobilization of anti-aflatoxin B1 antibody by UV polymerization of aniline and aflatoxin B1 detection via electrochemical impedance spectroscopy.

In the study, we investigated the practicality of the UV polymerization of aniline for anti-aflatoxin B1 antibody immobilization, and utilization of the resulting biosensor in the impedimetric determination of aflatoxin B1. The anti-aflatoxin B 1 antibody was physically immobilized on gold electrodes by UV polymerization of aniline at a fixed wavelength. The biosensor was based on specific interaction anti-aflatoxin B1 - aflatoxin B1 recognition and investigation of this recognition event by electrochemical impedance spectroscopy. A calibration curve was obtained in a linear detection range 1-20 ng/mL aflatoxin B1. Finally, the biosensor was applied to analysis of a real food sample.

The effect of using different probiotic cultures on conjugated linoleic acid (CLA) concentration and fatty acid composition of white pickle cheese.

Pickle white cheeses were produced from whole milk with five different probiotic cultures (Enterococcus faecium, Lactobacillus paracasei, Bifidobacterium longum, Bifidobacterium bifidum and Lactobacillus acidophilus). Conjugated linoleic acid (CLA) content of cheeses ranged from 3.52 to 3.92 mg/g. Probiotic differences and storage process have not affected the CLA contents of the samples statistically. There was no correlation between the CLA content of all probiotic cheeses and saturated fatty acids. A positive correlation between the CLA and linoleic acid contents of L. paracasei and L. acidophilus cheeses was observed.

Development of an impedimetric aflatoxin M1 biosensor based on a DNA probe and gold nanoparticles.

The present work describes the construction and application of a new DNA biosensor for detection of aflatoxin M1. In order to immobilize a thiol-modified single stranded DNA (ss-HSDNA) probe that specifically bound aflatoxin M1, a self-assembled monolayer of cysteamine and gold nanoparticles on the SAM were prepared on gold electrodes, layer-by-layer. The assembly processes of cysteamine, gold nanoparticles, and ss-HSDNA were monitored with the help of electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. K3[Fe(CN)6]/K4[Fe(CN)6] solution was used as a redox probe for electrochemical measurements. The biosensor provided a linear response to aflatoxin M1 over the concentration range of 1-14 ng/mL with a standard deviation of ±0.36 ng/mL. Finally, the biosensor was applied to a series of real milk samples.

Effects of fully and partial substitution of NaCl by KCl on physico-chemical and sensory properties of white pickled cheese.

White pickled cheeses were produced with different salting treatments, vacuum-packed in polyethylene containers, and stored at 4 +/- 1 degree C for 90 days. Five different concentrations of NaC1, KC1 or NaCl/KCl mixtures (sample A, 100% NaCl; sample B, 100% KCl; sample C, 75% NaCl + 25% KCl; sample D, 50% NaC1+50% KCl; sample E, 25% NaCl+75% KCl) were applied in the production of cheeses. Some physical, chemical and sensory properties of the samples were monitored at 0, 15, 30, 60 and 90 days of ripening. The results obtained indicated that the cheese could be produced with the mixture of 75% NaCl + 25% KCl without negative effects on cheese quality.