The effect of antimicrobial properties of nano-encapsulated red quinoa and ginseng extracts on the shelf life of cream

Introduction: The cream is a product obtained from the physical separation of milk and its conversion from fat emulsion to fat-free milk. Milk, its products like cream, are susceptible to microbial spoilage. Often, the color, smell, and taste of dairy products become undesirable due to the decomposition of existing proteins and fats with enzymes produced by microorganisms. The main cause of spoiled milk and its products that are kept at low temperatures is psychrophilic bacteria. Pseudomonas, Bacillus, and Streptococcus can be mentioned as psychrophilic bacteria. They grow well at a temperature lower than 15°C and can grow at a temperature of 4°C. Due to their proteolytic and lipolytic properties, these bacteria easily spoil milk even if it is kept at relatively low temperatures. Natural extracts with antimicrobial properties can be used to reduce the microbial load of dairy products, including cream. Polyphenols are the most important and numerous secondary groups of metabolites in the plant kingdom. These compounds play a role in defense against ultraviolet rays, oxidizing agents or invasion, and some plant pathogen agents. Quinoa belongs to Chenopodiaceae family, Chenopodium genus. Its plant name is Willd quinoa Chenopodium. Quinoa is a native cereal of South America. Quinoa and its products are rich in macronutrients, such as protein, polysaccharides, and fats, and also rich in micronutrients, such as polyphenols, vitamins, and minerals. Ginseng belongs to the Araliaceae family, and it is found throughout East Asia and Russia. The properties of this plant include its anti-inflammatory, antioxidant, anti-obesity, anti-allergy, anti-blood pressure, memory improvement, sexual enhancement, anti-diabetes properties, and anti-tumor properties. Ginseng also adjusts metabolism, immune functions, and blood pressure. Ginseng plant and red quinoa seeds contain high phenolic and flavonoid compounds and also have antimicrobial properties. On the other hand, extraction affects the compounds in the extracts. Extraction with the help of ultrasound is one of the green extraction methods. The encapsulation method is used to protect bioactive compounds (polyphenols, enzymes, antioxidants, micronutrients), and its purpose is to protect bioactive compounds from harmful environmental effects, and to control release. On the other hand, so far no research has been done in the field of investigating the antimicrobial effect of quinoa and ginseng extract coated with different walls (chitosan, whey protein, chitosan/whey protein) on the shelf life of cream .In this research, extracts from ginseng and red quinoa seeds were obtained by ultrasound prop. Then the extracts were nano-microcoated. The antimicrobial effect of the nano-encapsulated extracts on the cream was investigated.
Material and methods: In this extraction process, an ultrasound probe was used. The ratio of solvent to sample was 10:1. First, the dried powder was added to the desired solvent, and the ethanol-water solvent with the ratios (50:50) and (80:20) was separately subjected to ultrasonic waves with a frequency of 37 Hz and an intensity of 100 and a temperature of 40°C for 15 minutes was placed. Then, the chemical compounds of the obtained extracts were measured using GC-MS. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of ginseng and quinoa extracts were determined with an ethanol-water solvent with two different ratios (80-20 and 50-50). Then nano-emulsions containing ginseng, quinoa, and ginseng + quinoa mixture with different walls (chitosan, whey protein, chitosan/whey protein) were prepared. Encapsulation efficiency, particle size, and pH of nanoemulsions were investigated. Also, the antimicrobial properties of the cream containing nano-encapsulated extracts on different bacteria (Staphylococcus aureus, Bacillus subtilis, Salmonella, E. coli) at two temperatures of 4 and 25 degrees Celsius during the storage period of 14 days (the first day, 7th day, 14th day) was measured.
Results and discussion: The highest phenolic composition in ginseng and quinoa extracts was related to m-coumaric acid (111.09) and ellagic acid (73.88) microgram/gram, respectively. The highest amount of flavonoid compounds in ginseng and quinoa extracts belonged to catechin and rutin, respectively (29.6) and (34.12) micrograms/gram. The amount of MBC of Staphylococcus and Bacillus was higher in the ginseng extract. However, the MBC and MIC of E. coli and Salmonella bacteria were higher in quinoa extract. The pH of nanoemulsions varied between of 5.86-6.11 and the chitosan wall had the smallest size and the highest encapsulation efficiency. In the present study, nanoemulsions with chitosan walls and cheese juice had the highest (72.79 containing quinoa extract) and the lowest (59.9 containing ginseng and quinoa extract in a ratio of 1:1) encapsulation efficiency, respectively. Quinoa extract nano-encapsulated with chitosan wall had effects on reducing the number of tested bacteria (Staphylococcus aureus, Bacillus subtilis, Salmonella, E. coli) than other extracts. In the cream containing nano-encapsulated quinoa extract, on the 14th day, Staphylococcus was 2.19 and 1.63 logarithms at 4 and 25 °C, respectively. The number of Bacillus cereus at 4 and 25 °C was logarithm 1.03 and 1.9, respectively. However, Salmonella at 4 and 25 °C were 2.73 and 2.36 logarithms, respectively, and E. coli were 2.88 and 2.47 logarithms, respectively. After the quinoa extract, the mixture of ginseng and quinoa extracts had the most effective in reducing the number of bacteria, and finally, the nano-encapsulated ginseng extract showed the least effect in reducing these four bacteria present in the treated creams. Also, the rate of reduction of Staphylococcus and Bacillus was higher at 4°C compared to 25°C. Because Staphylococcus and Bacillus are mesophilic and thermophilic, respectively, which grow more easily at high temperatures and are sensitive to low temperatures. But Salmonella and E. coli were more sensitive to 25 °C than 4 °C. According to the results, different extracts had the most reducing effect on Bacillus cereus at 4°C and the least reducing effect on E. coli at 4°C.
Conclusion: Given that the results showed that quinoa and ginseng extracts have various phenolic and flavonoid compounds. Also, the MBC and MIC of the extracts showed high antibacterial properties. The use of chitosan as the wall of nano-encapsulated extracts was better than other walls in terms of encapsulation efficiency and particle size. Also, nano-coated quinoa extract with chitosan wall added to cream during storage at 4 and 25 degrees Celsius had a greater effect in reducing the tested bacteria (Staphylococcus aureus, Bacillus subtilis, Salmonella, E. coli) than other extracts, which indicated the higher antimicrobial properties of quinoa extract and also the better retention of these extract compounds by the chitosan wall. As a result, quinoa extract coated with chitosan wall can be used in fat-based dairy products, including cream, due to its natural antimicrobial properties. Because it reduces the microbial load of dairy products and thus increases the shelf life of dairy products.