Adjunct cultures are non-starter microorganisms contributing to the development of favorable flavor and texture during cheese ripening. The present study was designed to isolate and characterize potential adjunct cultures of lactic acid bacteria (LAB) from pickled Domiatti cheese and Ras cheese. Fifty-four cheese samples including 33 and 21 samples of pickled Domiatti cheese and Ras cheese, respectively were randomly collected from Mansoura city and villages in its vicinity and assessed for their flavor by panelists. Given the association of the adjunct cultures with typical flavor in cheese, cheese samples with "good" or "acceptable" flavor were further analyzed as a potential source of adjunct LAB cultures. A total of 162 suspected LAB isolates could be recovered from theses samples, of which 37 and 4 isolates were confirmed to belong to the Enterococcus and Lactobacillus genera, respectively. Further biochemical identification to the species level showed that the Enterococcus isolates involved Ent. faecalis (2 isolates), Ent. faecium (7 isolates), Ent. gallinarum (2 isolates), Ent. durans (1 isolate), Ent. mundtii (2 isolates), Ent. casseiliflavus (2 isolates), Ent. pseudoaavium (12 isolates), and Enterococcus spp. (9 isolates). Whereas, Lactobacillus isolates could be identified as Lb. plantarum (1 isolate) and Lactobacillus spp. (3 isolates). Enterococcus and Lactobacillus isolates were examined for technological properties including acidity development, proteolytic activity, and lipolytic activity. They showed phenotypic diversity in those technological characteristics. Isolates were also assessed for safetyassociated traits including antibiotic resistance, biogenic amine production, and hemolytic activity. Enterococcus isolates showed resistance to several antibiotics and were able to produce the biogenic amines histamine and tyramine. Hemolytic activity could be also detected in those isolates. Lactobacillus cultures showed resistance to only 2 out of 9 antibiotics and were unable to produce histamine or tyramine. They did not also show hemolytic activity. This study presents a collection of Enterococcus and Lactobacillus isolates to be assessed for use as adjunct cultures based on their technological and safety-related traits.

No abstract

The effect of fortification with both honey and olive oil on yoghurt quality was investigated. Control yoghurt was made using classic yoghurt culture and whole milk. Fou other yoghurt treatments were made by ABT culture and whole milk fortified with 0+0, 2+1, 4+2, and 6+4% of honey and virgin olive oil respectively. The sixth treatment was prepared using ABT culture and skim milk contained 6% honey + 4% virgin olive oil. Changes in rheological, chemical, microbial and organoleptic properties of yoghurt were monitored during refrigerated storage (4°C) for 15 days. Mixing of yoghurt milk with honey and olive oil to milk showed a slight decrease in the rate of acidity development. Fortification of milk with honey and olive oil had no clear effect on coagulation time, but increased curd tension and decreased curd syneresis values. Addition of honey and olive oil increased acidity, TS, fat, ash and TVFA contents of the examined yoghurt while there were no differences in TN and WSN values. Yoghurt made with honey and olive oil had lower TVBC, moulds and yeasts numbers as compared with control. Adding of honey and olive oil stimulated the growth and viability of bifidobacteria which helped in maintenance their counts above the recommended levels (10 6 cfu.g-1) for a probiotic effect. Finally, supplementation of yoghurt with honey and olive oil greatly improved the sensory evaluation scores.

In this study yoghurt was made from cold stored buffaloe's or cow's milk for 24 or 48 hours. Also, the effect of addition of morning and evening milk to refrigerated stored milk on some properties of yoghurt was studied. Results showed that yoghurt made from buffaloe's milk possessed higher acidity, TS, fat, ash and TN while had lower WSN, WSN/TN, NPN, NPN/TN and TVFA values than those of made from cow's milk. Blending various lactations milks with cold stored milk raised the acidity and TVFA values and lowered the pH values of the resultant yoghurt and had no clear effect on TS, fat, ash, TN, TN/DM, WSN, WSN/TN, NPN and NPN/TN. Refrigerated storage of buffaloe's or cow's milk increased the acidity and TVFA values of yoghurt and had no clear effect on TS, fat, ash, TN, TN/DM, WSN, WSN/TN, NPN and NPN/TN. Yoghurt made from buffaloe's milk contained higher numbers of total viable bacterial count (TVBC), lactic acid (LAB), psychrophilic bacteria, proteolytic, lipolytic, colifom, sporoformers, moulds and yeast. Mixing evening and morning milk with cold stored milk or cooling milk for 24 or 48 hours increased the mentioned microbial groups numbers of yoghurt. Yoghurt prepared from buffaloe's milk had higher score point than that of cow's milk. Adding various lactations buffaloe's or cow's milk to refrigerated stored milk and storing milk at 4°C for 24 and 48 hours had no clear effect on sensory evaluation of yoghurt.

Continue to hypothesize that honey is a storehouse of beneficial bacteria and most of these isolates are levansucrase producers. Accordingly, ten bacterial strains were isolated from different honey sources. Four honey isolates that had the highest levansucrase production were identified by the partial sequencing of the 16S rRNA gene as Achromobacter sp. (10A), Bacillus paralicheniformis (2M), Bacillus subtilis (9A), and Bacillus paranthracis (13M). The cytotoxicity of the selected isolates showed negative blood Hemolysis. Also, they are sensitive to the tested antibiotics (Amoxicillin + Flucloxacillin, Ampicilin, Gentamicin and Benzathine benzaylpencillin.). All the isolates exhibited high stability on the alkaline side (pHs 9,11) and could tolerate severe acidic conditions (29-100%). The tested isolates recorded complete tolerance to both H2O2 and the bile salt (0.3 % Oxgall powder) after 24h incubation. The cell-free supernatant of the examined strains had antifungal activities against Candida albicans with varying degrees. Also, isolates 2M and 13M showed strong activities against Staphylococcus aureus. Isolate 10A showed the highest antioxidant activity (91.45%) followed by 2M (47.37%). All isolates produced cholesterol oxidase and lipase with different levels. Besides, the four isolates reduced LDL (low-density lipoprotein) to different significant values. The cholesterol-reducing ability varied not only for strains but also for the time of incubation. The previous results recommended these isolates be used safely in solving the LDL problem.