Kefir is a fermented milk beverage and known to have positive effects on gut microbial diversity and human health. In this study, digested and undigested kefir samples were compared for changes in their antihypertensive, antidiabetic, antioxidant and antimicrobial activities. Results showed that the amount of total phenolic substances, 2,2-diphenyl-1-picrylhydrazyl radical scavenging (DPPH) activity, and the angiotensin-converting enzyme inhibitor (ACE-I) activity increased from 43.76 AE 0.005 mg gallic acid equivalents (GAE)/L, 4.20 AE 0.55%, and 9.91 AE 3.90% in undigested kefir to 668.16 AE 3.332 mg GAE/ L, 63.06 AE 0.64%, and 98.88 AE 0.42% in digested kefir, respectively. While the dipeptidyl peptidase IVinhibitory (DPPIV-I) activity of undigested kefir increased by 19.11 AE 7.35% after digestion, the optical density of the ferric-reducing antioxidant power (FRAP) decreased from 1.188 AE 0.05 to 0.278 AE 0.009, and the protein amount decreased from 101.4 mg L À1 to 12.42 mg L À1 in digested kefir. No antimicrobial effect was observed in undigested kefir, whereas, digested kefir samples were active, but only against Escherichia coli. These results show that the gastrointestinal digestion processes of kefir generally increase the number of bioactive molecules, and the digestion process must be taken into account to determine the biological capability of foods.

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X-prolyl dipeptidyl aminopeptidase (PepX) is an intracellular enzyme from the Gram-positive bacterium Lactococcus lactis spp. lactis NRRL B-1821, and it has commercial importance. The objective of this study was to compare the effects of several cell disruption methods on the activity of PepX. Statistical optimization methods were performed for two cavitation methods, hydrodynamic (high-pressure homogenization) and acoustic (sonication), to determine the more appropriate disruption method. Two level factorial design (2FI), with the parameters of number of cycles and pressure, and Box-Behnken design (BBD), with the parameters of cycle, sonication time, and power, were used for the optimization of the high-pressure homogenization and sonication methods, respectively. In addition, disruption methods, consisting of lysozyme, bead milling, heat treatment, freeze-thawing, liquid nitrogen, ethylenediaminetetraacetic acid (EDTA), Triton-X, sodium dodecyl sulfate (SDS), chloroform, and antibiotics, were performed and compared with the high-pressure homogenization and sonication methods. The optimized values of high-pressure homogenization were one cycle at 130 MPa providing activity of 114.47 mU ml(-1), while sonication afforded an activity of 145.09 mU ml(-1) at 28 min with 91% power and three cycles. In conclusion, sonication was the more effective disruption method, and its optimal operation parameters were manifested for the release of intracellular enzyme from a L. lactis spp. lactis strain, which is a Gram-positive bacterium.

Traditional opioids have been used for the people who suffer from cancer, burns, surgery, HIV/AIDS, and other serious illness pains for years. However, numerous side effects like dizziness, apnea, physical dependence, tolerance, addiction, nausea, and vomiting push the researchers to look forward to the new opioid options. The opioid peptides which derived from foods provide significant advantages as the safe and natural alternative. The researchers reported that it is also promising a new functional food and nutraceutical. In this chapter, the type of food-derived opioids, their origins, possible receptors, their amino acid sequences, opioid effects, production techniques, and health benefits are reviewed.

Thirteen different mostly consumed cheese samples were obtained from different provinces in Turkey and were investigated in terms of contents of ergosterol, patulin and Ochratoxin A (OTA). Ergosterol, patulin and OTA analyses were carried out by using the apparatus of high-performance liquid chromatography (HPLC). Ergosterol contents of samples ranged from 30.27±0.69 to 144.76±9.41 mg/kg. The values of OTA in the samples were ranged from 6.96±0.05 to 41±0.2 µg/kg. Ergosterol was significantly correlated with OTA (r = 0.99, R2 = 0.98). According to this high correlation, ergosterol might be used as a more readily measurable indicator of potential OTA production. No patulin was detected in all samples. Absence of patulin on cheese samples may be explained with unsuitable media for patulin producing.