Food Biotechnology
Soheyl Reyhani Poul; Sakineh Yeganeh; Zeynab Raftani Amiri
Abstract
Introduction Since heat treatments and special standards are not used in the production of traditional (homemade) tomato paste, fungal and bacterial spoilage in the product occurs extensively during storage in the refrigerator (4°C). Astaxanthin extracted from aquatics has antimicrobial activity ...
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Introduction Since heat treatments and special standards are not used in the production of traditional (homemade) tomato paste, fungal and bacterial spoilage in the product occurs extensively during storage in the refrigerator (4°C). Astaxanthin extracted from aquatics has antimicrobial activity and color similar to tomato and can probably be effective in preventing spoilage of tomato paste. In addition, astaxanthin has other properties in the field of preventing and controlling diseases and maintaining human health, which justifies its use in food formulations as an enrichment. Since heat, enzyme, acid, etc. treatments are practiced during the production of tomato paste, these factors may change the structure and thus the function of astaxanthin. For this reason, astaxanthin nanoencapsulation is necessary for its use in tomato paste formulation. Materials and Methods In this research, first, astaxanthin was extracted from Haematococcus pluvialis microalgae using the acid-acetone combined method. Then, this pigment was nanoencapsulated using maltodextrin-sodium caseinate coating and the resulting nanocapsules were used together with the pure form of astaxanthin in the formulation of tomato paste. The research treatments were control, tomato pastes containing 3 and 6% astaxanthin (A and B, respectively) and also 3, 6 and 9% nanocapsules carrying the pigment (C, D and E, respectively). These treatments were kept at refrigerator for 28 days and were evaluated (on days 0, 7, 14, 21 and 28) in terms of the total number of fungi, Howard's number (HMC), pH, fungal flora, total bacteria count, amount of lactic acid bacteria and sensory properties. This research was conducted in a completely randomized design. Data were analyzed by One-way Anova and the difference between the means was evaluated by Duncan's test at 95% confidence level. Results and Discussion The results showed that the fungi proliferation, total count and lactic acid bacteria were slower than the control during the storage period in the treatments containing astaxanthin and its carrying nanocapsules, and the minimum number of the mentioned microorganisms and Howard's number were related to treatments D and E (p>0.05). Treatments C, B and A were ranked next in this respect (p<0.05). The number of fungi in two treatments D and E from day 0 to 28 varied from 128 to 332 cfu/gr. Also, the Howard number of these treatments was recorded from 18 to 34% in the mentioned time period. However, these two indices in the control ranged from 121 to 792 cfu/gr and 18 to 91%, respectively, during the storage period. The count of total bacteria and the amount of lactic acid bacteria in the control on day 28 were equal to 8.9 cfu/gr and 311 mg/kg, respectively, but these two values were recorded in the E and D treatments on the same day, about 4.8 cfu/gr and 110 mg/kg, respectively. Counting the total number of fungi, bacterias and also Howard's number in control and other treatments showed that the effect of nanocapsules carrying astaxanthin on microbial growth and proliferation is significantly greater than pure astaxanthin (p<0.05). The pH of the treatments varied from 3.9 to 5.8 during the storage period and the most standardized pH (3.9-4.4) was recorded in C, D and E (p>0.05) treatments (p<0.05). The pH of two treatments A and B (p>0.05) was higher than the three mentioned treatments and lower than the control (p<0.05). This finding showed that nanocapsules carrying astaxanthin have a greater effect on controlling the pH of tomato paste than pure astaxanthin during storage at refrigerator (p<0.05). The identification of the fungal flora of the treatments on the 28th day confirmed that two genus of Penicillium and Aspergillus form the main flora of the product. The results of the sensory evaluation of the treatments on day 0 showed that adding astaxanthin and its carrier nanocapsules does not change the color, aroma, taste and texture indicators (subsequently the general acceptance) of tomato paste (p>0.05). On the 28th day, the mentioned sensory indices only in the two treatments D and E were not significantly different from the 0 day, but they changed negatively in the other treatments (p<0.05). Conclusion According to the findings of the present research, astaxanthin extracted from Haematococcus pluvialis microalgae has the ability to inhibit fungal and bacterial spoilage and stabilize the sensory properties of tomato paste stored at refrigerator. This properties were improved by adding nanoencapsulated pigment using maltodextrin-sodium caseinate combined coating. Since there were no significant differences between the two treatments containing 6% and 9% of nanocapsules carrying astaxanthin (D and E) in terms of quality indices and microbial spoilage, therefore, the treatment containing 6% nanocapsules is introduced as the optimal treatment.
Food Biotechnology
Masume Atharinia; Nasrin Zonourian; Sare Davarzani
Abstract
IntroductionTomato paste is one of the processed tomato products that has a long shelf life and is used as an important food ingredient all over the world. According to global statistics, Iran is among the top ten producers of tomato paste in the world, Iran ranks fourth to fifth in the world in the ...
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IntroductionTomato paste is one of the processed tomato products that has a long shelf life and is used as an important food ingredient all over the world. According to global statistics, Iran is among the top ten producers of tomato paste in the world, Iran ranks fourth to fifth in the world in the field of aseptic paste production. Alicyclobacillus bacteria are considered as a risk for pasteurized acidic food industries. These bacteria enter the product through soil-contaminated fruits, production equipment of the factories and finally produce metabolites such as guaiacol, causing an unpleasant taste in the product. Materials and Methods In order to investigate the microbial contamination of canned tomato paste in the country, 46 samples of canned tomato paste in the amount of 184 cans of 800 grams were purchased from the market. Regarding the purchase of samples from the market, we tried to buy a different production date and production series for each sample (approximately 4 cans for each brand from each production series). The purchased samples were sent to the Microbiology Department of the Standard Research Institute laboratory for microbiology tests. At the same time, the culture media of thermophilic bacteria (Orange Serum Agar, Thermoacidurans Agar from 4 available brands) were tested for performance control. The canned tomato paste samples were incubated at 30°C ± 1°C for 14 days and 55°C ± 1°C for 7 days. Results and Discussion The contents of both examined samples were tested separately for thermophilic bacteria, mesophilic bacteria, mold and yeast. Out of the 46 samples prepared with different production dates and production series, which were 46 cans of tomato paste, 28 samples were positive in terms of contamination with thermophilic bacteria. According to the number of contaminated samples, it was found that 60.86% of the samples were contaminated. Colonies grown on Thermoacidurans Agar medium were examined morphologically. For further investigations, gram staining was performed. All the stained colonies morphologically showed the form of gram-positive rod-shaped bacilli. Biochemical tests including catalase and oxidase were performed to identify Alicyclobacillus species. All the grown colonies were catalase positive and oxidase negative. The final identification of the species was done by performing molecular tests based on specific primers designed from Alicyclobacillus gene. These tests were performed in three stages: genomic DNA extraction, polymerase chain reaction and electrophoresis. Using the PCR method, the grown colonies were analyzed for two types of bacteria, Alicyclobacillus acidocaldarius and Bacillus coagulans. According to the results obtained from sequencing with designed primers in the NCBI database, it showed 100% similarity with the registered sequences, which are all different strains of the Alicyclobacillus acidocaldarius species. None of the colonies were detected as Bacillus coagulans species. Since Alicyclobacillus acidocaldarius was isolated from soil for the first time, the presence of these bacteria in the product indicates the contamination of raw materials with soil. ConclusionIn this research, the presence of Alicyclobacillus bacteria in canned tomato paste was confirmed. Due to the high heat resistance of this bacteria, there is a possibility of the presence of Alicyclobacillus in the all stages of tomato paste production, which have entered the product through the soil, and 95°C ± 3°C pasteurization temperature in 30 minutes is not effective in removing this bacteria completely. Most acidophilus thermophilic bacteria, such as Alicyclobacillus family, are not pathogenic bacteria. Their presence in food may make the food taste bad or smelly, but it does not pose a risk to the health of the consumer. Therefore, in order to reduce the risk of spoilage and to prevent the growth of bacterial spores in the product, it is essential not to expose the product to high temperatures for a long time. It is also necessary to perform rapid cooling after heat treatment and keep the product at a temperature below 30°C. AcknowledgementThis article is the result of a common research project of Microbiology and Biology Research Group of Standard Research Institute and Kermanshah Standard Regional Research Group. We hereby thank and appreciate the cooperation of the microbiology research group of the Standard Research Institute and the Kermanshah General Directorate of Standards. We are also very grateful to Rogin Talk Company as the employer of this project.
