Package of the Summer 2022

Abstract

Background and Objective: Salivary microbiota, including bacteria shed from oral surfaces, is individualized, temporally stable and affected by the environmental factors such as diet, lifestyle and oral hygiene. Salivary microbiota is nonpathogenic and commensal; however, if microbiota colonizes into the intestines, they could alter gastrointestinal microbiota and result in development of several chronic inflammatory diseases, foremost autoimmune diseases and gastrointestinal cancers. There are few studies that assessed salivary microbiota in autoimmune gastrointestinal disorders. This may help researchers find novel personalized therapeutic approaches for the gastrointestinal diseases. Therefore, the aim of this review was to discuss alterations of salivary microbiota composition in gastrointestinal disease progress, including celiac disease, inflammatory bowel disease and gastrointestinal cancers.

Results and Conclusion: This study suggested that oral microbiota composition is linked to chronic inflammatory diseases by changing the immune system responses through increasing the production of inflammatory cytokines and mediators. Investigation of saliva microbiota is becoming an important part of diagnosing gastrointestinal diseases and changes in the composition of oral microbiota can predict risks of disorder progression in high-risk individuals.

Conflict of interest: The authors declare no conflict of interest.

Abstract

Background and Objective: Spirulina platensis includes excellent bioactive compounds, which provide health-promoting effects. However, use of Spirulina platensis in foods includes limitations due to its unpleasant flavor and taste for some people. Fermented milk products include typical taste and flavor of fresh acid and can be combined with Spirulina platensis. Probiotics of Lactobacillus plantarum Dad 13 and Streptococcus thermophilus Dad 11 isolated from traditional buffalo milks can be used as starter culture strains for the fermented milks. This study investigated lactic acid bacterial growth, acid production and physicochemical characteristics of the fermented milks with Spirulina platensis.

Material and Methods: Milk fermentation was carried out using addition of various concentrations (0.15, 0.3, 0.45 and 0.6%) of Spirulina platensis powder and then microbial cell growth, acid production and antioxidant activity were investigated. Fermented milks with selected concentrations of Spirulina platensis were assessed within 24 h of fermentation at 37 °C using single and mixed cultures to study various aspects of cell growth, acid production, viscosity, water holding capacity and color.

Results and Conclusion: Increases of Spirulina platensis concentrations in fermented milks increased the microbial cell growth, acid production and antioxidant activity. During milk fermentation by adding 0.3% of Spirulina platensis, cells propagated and total lactic acid bacteria and probiotic cell counts reached to respectively 8.73-9.19 and 8.92 log CFU ml^-1 after 24 h. The titratable acidity reached to 1.08% and pH decreased to 4.41. Viscosity increased significantly after 12 h of fermentation, compared to the controls. Fermented milks with Spirulina platensis addition by Lactobacillus plantarum Dad 13 and Streptococcus thermophilus Dad 11 cultures can be developed as alternative functional fermented milk products.

Conflict of interest: The authors declare no conflict of interest.

Background and Objective: Pasteurization is one of the most widely used methods in decreasing of microbial loads in fruit juices. Unfortunately, high temperatures destroy anthocyanins and polyphenolic compounds. Nutritional status and quality of fruit juices can be improved using other decontamination methods such as ultrasound process. This study was carried out to investigate effects of ultrasound on contents of bioactive compounds and microbial loads of red-grape juice samples. Results achieved under the optimum conditions of ultrasonication were compared to those under thermal pasteurization.

Material and Methods: Effects of three variables of ultrasound time (2, 6 and 10 min), temperature (0, 30 and 60 °C) and power (10, 105 and 200 W) on total phenol content, anthocyanin and total microbial count of the red-grape juices were studied. Design of experiments was carried out using response surface methodology (Box-Behnken design) followed by optimization. Quality of the optimized samples was compared to the quality of controls pasteurized at 90 °C for 30 s. Total phenol content, anthocyanin and total microbial count were assessed using Folin-Ciocalteu assay, spectrophotometry and total plate count method, respectively.

Results and Conclusion: The maximum levels of phenols and anthocyanin compounds and the minimum microbial loads were achieved at 144.34 W for 2 min at 60 °C. Based on the results, contents of total phenol and anthocyanin in samples treated by ultrasound under optimal conditions were significantly higher than those in samples pasteurized by thermal process. No significant differences were seen between total microbial counts of the samples processed by ultrasonication and thermal pasteurization. These results indicated that more bioactive compounds of phenols and anthocyanins could be preserved in grape juices under ultrasonication than those under thermal processes. In addition, a similar safety scheme of the microbial load was achieved by optimizing the conditions of ultrasound treatment.

Conflict of interest: The authors declare no conflict of interest.

Abstract

Background and Objective: Phycocyanin is a blue pigment extracted from Spirulina platensis algae as an excellent alternative for the comparison of synthetic dyes in various industries, including food industries. The aim of the present study was to assess effects of copigmentation on the stability of phycocyanin pigments using spray drying method.

Material and Methods: An aqueous solution of phycocyanin (500 mg l^-1) was prepared at three pH values of 3, 5 and 7. Then, polyphenolic compounds containing rosmarinic acid, tannic acid and digallic acid (0, 75, 150, 225 and 300 mgl^-1) were separately added to the solution as copolymers. Pigment solutions were transferred into cylindrical containers with similar sizes under a light source at an intensity of 7000 l mm^-2 and ambient temperature. Color changes of the solutions were assessed for 14 d. Phycocyanin pigment solution was copigmented with tannic acid (the best copolymer) and mixed with a combination of maltodextrin and Arabic gum (100:0, 75:25, 50:50, 25:75 and 0:100). Ratio of the core to the wall was 1:10. Spray dryer was used for drying and stability of the dried coated pigment powder was assessed for 14 d by investigating the absorption reduction ratio at the maximum absorption wavelength of phycocyanin (620 nm) using spectrophotometer.

Results and Conclusion: Based on the results, using tannic acid (300 mgl^-1) as the best copigmenting compound induced higher resistance to phycocyanin. In addition, the most stable pigment treatment was seen with maltodextrin and Arabic gum coating (ratio: 100:0). In particle size, findings showed that the powder samples containing maltodextrin were larger than the samples with Arabic gum (350.2 and 40.1 nm, respectively). Moreover, results showed that phycocyanin copigmented with tannic acid included higher resistance to environmental changes and encapsulation using spray dryer was further effective in increasing stability of phycocyanin.

Conflict of interest: The authors declare no conflict of interest.

Abstract

Background and Objective: Carrageenans can be found in a group of red algae called Carrageenophytes (Gigartinaceae, Solieriaceae, Hypneaceae and Furcellariaceae); howe-ver, this substance has not been investigated in Laurencia species. In this study, two native species of Laurencia within the Persian Gulf were investigated to extract carrageenans. Therefore, the major aims of this study included extraction, optimization and purification of carrageenans from Laurencia snyderiae, a native red algae of Persian Gulf.

Material and Methods: Laurencia snyderiae and Laurencia papillosa were identified based on their morphological characteristics. An experimental design was carried out using Design Expert Software to produce and optimize extraction of semi-refined carrageenans. The software programmed 18 treatments based on temperature, boiling time and KOH concentration. Products of the treatments were prepared for rheometric analyses (viscosity measurements). Optimization was carried out using the software based on the maximum viscosity. Refined carrageenan efficiency was assessed using four extraction methods. Moreover, Fourier-transform infrared spectroscopy and nuclear magnetic resonance spectroscopy spectra were compared. Laurencia snyderiae was selected for further inves-tigation.

Results and Conclusion: Based on the rheometric analyses, a semi-refined carrageenan solution was identified as a non-Newtonian pseudo-plastic fluid. The optimum treatment was investigated for Laurencia snyderiae at 65 °C for 35 min at KOH concentration of 7% w/v. Results of these two analyses showed that the refined carrageenans from Laurencia snyderiae included the lambda type. The highest efficiency was achieved using dialysis method (37%). Based on the abundance of the Laurencia snyderiae on the Persian Gulf coasts in all seasons, further studies on carrageenan with higher purities enable use of these substance in various industries. Broader rheological studies can precisely assess characteristics of the investigated carrageenans.

Conflict of interest: The authors declare no conflict of interest.

Background and Objective: During the manufacture and storage of probiotic products, there are always possibilities that probiotics be exposed to harmful stresses such as high temperature, low pH, various osmotic pressures and high oxygen levels, which can decrease the number of living cells. Encapsulation is one of the methods used to protect living cells such as probiotic bacteria from environmental challenges. Up-to-date, various compounds with abilities to protect bacteria during freeze-drying and to increase viability during storage have been identified. In this study, alginate with calcium chloride was used to encapsulate probiotic bacteria using extrusion method. Then, effects of sucrose and skim milk as cryoprotectants and yeast powder containing beta-glucan as prebiotic on the survival of these bacteria were investigated.

Material and Methods: The Homogeneous solution of bacteria with alginate and cry protectants were manually extruded into a calcium chloride solution. After 30 min of agitation, shaped beads were separated. For the comparison, bacterial population were enumerated in the primary culture, after encapsulation, freeze-drying and 1 week of storage at room conditions (N0, N, NF and N1_w, respectively). To assess colony-forming unit per ml of the samples, first 1 g of fresh beads was dissolved in 9 ml of trisodium citrate and then serial dilution and pour plate techniques were carried out. Plates were incubated for 24-48 h and colonies were counted.

Results and Conclusion: Results showed that encapsulation of bacteria with alginate and calcium chloride alone was 51% effective while use of yeast powder and sucrose with alginate increased the encapsulation efficiency to 97 and 99%, respectively. Furthermore, use of skim milk with alginate and sucrose resulted in the highest survival rate after 1 week of storage at room conditions. Therefore, encapsulation of probiotic bacteria with alginate layer and yeast powder containing prebiotics, sucrose and skim milk can be effective in survival of these bacteria.

Conflict of interest: The authors declare no conflict of interest.