The objective of the present study was to utilize whey and permeate as the by-products of the cheese industry after mixing with kumquat purée and/or paste for producing functional beverages. Physical, chemical, physicochemical, microbiological and sensory properties of kumquat fruit and its purée and paste were studied. The results indicated that kumquat purée and paste are good sources of β-carotene, vitamin C, minerals such as calcium, potassium and magnesium, total phenolic acids and flavonoids. In addition, they have high antioxidant capacity. Physicochemical, microbiological and sensory properties of the prepared functional beverages during cold storage periods were determined. The obtained results indicated that ascorbic acid and β-carotene of all beverages were higher than those of whey and permeate only, with a high level of total phenols, flavonoid content and antioxidant activity. Generally, sensory evaluation of the prepared beverages showed that the addition of purée and paste of kumquat fruit to whey and permeate increased the overall acceptability of these beverages. Total count was in permissible limit while the coliform and moulds & yeasts counts were not detected in all beverages during storage at 4±1°C for 28 days. Beverages containing purée and paste of kumquat fruit could be recommended as new acceptable functional products.

Background: Researchers have focused on isolating and identifying the bacteriocin producing lactic acid bacteria from various food systems especially dairy products. Molecular techniques have been recently used for rabid identification of bacteriocins rather than time-consuming biochemical characters. Global climate disturbances can affect the diversity of beneficial microorganisms in dairy and their products, especially lactic acid bacteria, so it is worth to evaluate their bacteriocinogenicity in different climates. Thus, the aim of this study was to screen for predominant bacteriocin producing lactic acid bacteria (LAB) in traditional dairy products of Luxor governorate at Upper Egypt and determine their bacteriocin-encoding genes. Results: Eighty-six strains of the LAB were isolated from raw milk and traditional dairy product of Luxor province, Egypt, in which 76.1% and 23.9% were identified as lactic acid bacilli and cocci, respectively. On the basis of their antibacterial potentials, 30 out of 68 LAB isolates were found to be antimicrobial producers. These isolates exhibited a potential antibacterial activity against Salmonella paratyphi B, Escherichia coli, Staphylococcus aureus, and Proteus mirabilis, except for Listeria monocytogenes. LAB isolates were analyzed using species-specific PCR; results emphasized that 22 of isolates were identified as Lactobacillus plantarum, while 8 were Leuconostoc mesenteroides. According to the sequencing of isolates, two strains named Lactobacillus plantarum Egypt 2018 (accession no. MH817034) and Leuconostoc mesenteroides Egypt 2018 (accession no. MH817035) were identified. Detection of bacteriocin-encoding genes was performed by polymerase chain reaction (PCR). The results emphasized that almost all tested Lb. plantarum strains (n = 10) possess both plnA and plnEF genes, whereas the gene encoding mesentericin Y105 was detected in one Lc. mesenteroides of the examined isolates. Conclusions: This study was effective for the rapid detection of bacteriocin producing strains within dairy products. Extracted bacteriocin could be a valuable source of natural food biopreservative.

Background Bacteriocins are proteinaceous compounds produced from lactic acid bacteria. Bacteriocins are well-known for their antibacterial potential and safety for application in food. However, the commercial availability of bacteriocin is facing several limitations; among them is the low yield and short stability period. That calls for a new strategy for overcoming these hurdles. Among these approaches is incorporating bacteriocin in nanoparticles. So, the aim of this study was to enhance the plantaricin produced from isolated Lactobacillus plantarum strain using nanotechnology. Results In this study, the plnEF genes encoding plantaricin EF have been identified and sequenced (accession number of MN172264.1). The extracted bacteriocin (EX-PL) was obtained by the ammonium sulfate method. Then, it was used for biosynthesizing plantaricin-incorporated silver nanoparticles (PL-SNPs). The synthesized nanoparticles were confirmed by SEM-EDAX analysis. The antibacterial activity of both combined (PL-SNPs) and extracted plantaricin (EX-PL) were tested against some strains of foodborne pathogenic bacteria. The results revealed that the antibacterial activities were increased by 99.2% on the combination of bacteriocin with the silver nanoparticle. The MIC of EX-PL (7.6 mg/mL) has been lowered after incorporating into silver nanoparticles and reached 0.004 mg/mL for PL-SNPs. Despite that extracted plantaricin showed no inhibitory activity towards Listeria monocytogenes, plantaricin-incorporated silver nanoparticles displayed inhibitory activity against this strain. Furthermore, the stability period at 4 °C was increased from 5 days to 60 days for EX-PL and PL-SNPs, respectively. Conclusions Plantaricin-incorporated silver nanoparticles possess higher antibacterial activity and more stability than the free one, which makes it more fitting for combating foodborne pathogens and open more fields for applications in both food and pharmaceutical industries. Graphical abstract

ariesh cheese is one of the most traditional Egyptian dairy products, it is known since the phararonic era. Parsley is an important source of phytochemicals such as phenolic, flavonoid compounds and vitamins. Hence, the aim of this study was to produce functional kariesh cheese supplemented with dried parsley by using low sodium salt. Chemical composition of parsley were studied. Furthermore, the effect of addition parsley in Kariesh cheese on physicochemical properties, microbiological count, rheological and sensory properties were evaluated. Results from HPLC showed that parsley contains high percent of rosmarinic, benzoic, E-vanillic & ellagic acids and hesperidin. Also, parsley has found to contain a variety of water soluble vitamins like nicotinic acid, B12, riboflavin and vitamin C. Kariesh cheese was made from skim milk supplemented with parsley (0.25, 0.5 and 0.75 %), and/or 1% low sodium salt (LSS) as substitution for commercial salt. Results indicated that moisture decreased whereas fat and protein contents increased with increasing adding ratio of parsley. Total bacteria count increased in the treatments which have LSS, where it was lower than the other treatments that contain parsley. In textural profile analysis, adding LSS with parsley caused increase in hardness, cohesnivess, springiness, chewiness and gumminess compared with control. From organoleptic view, all treatments were acceptable but the treatment which contains 1% LSS with 0.5% parsley showed the best organoleptic attributes among other treatments compared with control.

Background and Objective: The application of the exopolysaccharide-producing starter culture for improving the texture and technical properties and evaluating flavor profile of low-fat Ras cheese was studied. The experimental design was performed to compare flavour compounds of traditional and exopolysaccharide producing starters (EPS) for different levels of fat milk cheese. Materials and Methods: Control (4% fat) with traditional starter, T 1 (0% fat) with EPS, T 2 (1% fat) with EPS), T 3 (2% fat) with EPS and T 4 (3% fat) with EPS were used. The physicochemical, textural profile analysis and organoleptic properties of fresh and stored cheeses (4 months) were determined. Also, the microscopic structural changes in fresh low-fat Ras cheese with EPS were evaluated. Results: The results indicated that addition of EPS producing cultures with decreasing fat of cheese milk lead to an increase in the moisture of treatments as well as hardness, cohesiveness, springiness, chewiness and gumminess of the resultant cheese. The data indicated that control cheese (full-fat and without EPS-producing cultures) had the lowest values of acidity. The changes in pH values among all cheese treatments and during storage period followed opposite trend to that of titratable acidity. There were negative correlation between the rate of fat reduction and the values of SN (soluble nitrogen). Conclusion: Addition of EPS-producing cultures in Ras cheese milk improved sensory evaluation of resultant cheese, whereas cheese with 3% fat and EPS-producing culture (T 4 ) selected as best Ras cheese sample.