JOURNAL OF NUTRITION FASTING AND HEALTH The Assessment the Quality of Probiotic Yogurt Using the Rosmarinus Officinalis Essential Oil 1 2 Ramona Massoud , Anousheh Sharifan 1. Department of Food Research, Standards Organization, Tehran, Iran. 2. Department of Food Science and Technology, Science and Research Branch, Islamic Azad University, Tehran, Iran. A R T I C L E I N F O A B S T R A C T Article type: Introduction: Antimicrobial compounds have recently attracted the attention of researchers across Research Paper the world. Essential oils (EOs) could be used as potent herbal antimicrobial materials and natural antioxidants in the food industry. The present study aimed to assess the effects of Rosmarinus Article History: officinalis essential oil (REO) with variable phenol contents on the properties of probiotic yogurt Received: 14 Apr 2020 containing Bifidobacterium bifidum. Accepted: 16 Jun 2020 Methods: Yogurt was prepared by adding Lactobacillus bulgaricus and Streptococcus thermophilus as Published: 09 Aug 2020 the starter and the Bifidobacterium bifidum as the probiotic strains. REO was also added at the three concentrations of 1%, 2%, and 3%. Titratable acidity, pH, syneresis, and rheological, microbial, and Keywords: sensory properties were evaluated at three storage times (7, 14, and 21 days). The total phenol content Probiotic was approximately 8.93±0.11 milligrams of gallic acid. Bacterial activity Results: The bacterial activity significantly declined in all the samples during 20 days of storage Essential oil (P<0.05), and the addition of REO decreased the lowering rate of bacterial growth in the probiotic and Flow behavior starter strains over 21 days. Moreover, refrigerated storage decreased the pH and viscosity (P<0.05), Yogurt which increasing increased titratable acidity and syneresis (P<0.05). The probiotic yogurt with REO exhibited thixotropic non-Newtonian behavior, and the samples containing 1% REO had the highest scores of flavor, odor, texture, and overall acceptability. Conclusion: According to the results, high levels of phenolic compounds contributed to the biological, physicochemical, and rheological properties of probiotic yogurt, as well as its sensory scores. Please cite this paper as: Massoud R, Sharifan A. The Assessment the Quality of Probiotic Yogurt Using the Rosmarinus Officinalis Essential Oil. J Nutrition Fasting Health. 2020; 8(3): 176-185. DOI: 10.22038/jnfh.2020.47876.1260. Introduction yogurt occur due to the presence of nonvolatile Today, the consumption of functional foods has acids (e.g., pyruvic and lactic acid), volatile acids attracted attention owing to their health benefits (e.g., butyric and acetic acid), and carbonyl (1). Functional foods also affect the food compounds (e.g., acetaldehyde and diacetyl) industry, especially fermented dairy products (13). Compounds such as fruits, flavoring agents, with nutritional values, such as proteins, and sweeteners may be added to yogurt to vitamins, and minerals (2, 3). Such examples are promote its flavor (14). These additives may yogurt, kefir, soy milk, whey drinks, and Kashk affect microbial growth, texture, and flavor (drained yogurt) (4). during fermentation and storage due to the Numerous attempts have been made to fortify presence of phenolic compounds and their dairy products (5, 6). Probiotics are living interactions with proteins (15). microorganisms with beneficial health effects on Essential oils (EOs) are oily aromatic liquids that the consumers (7). are extracted from various plants (16, 17). The Bifidobacteria are well-known strains (8), and antimicrobial properties of EOs and spices could Bifidobacterium bifidum is considered to be the enhance the shelf life of foods (17) and inhibit the most important species of this genus (9). growth of the pathogens that could contaminate Bifidobacterium bifidum improves the food, as well as the microorganisms that are gastrointestinal tract function and immunity responsible for food spoilage (18). function against various diseases, such as Reports have been published on the antibacterial influenza (10). The viability of probiotics in effects of Mentha spicata and Mentha aquatica yogurt is often less than 6 log CFU/g during EOs against Bifidobacterium animalis, storage (11, 12). Changes in the final flavor of Staphylococcus aureus, Lactobacillus reuteri, and * Corresponding author: Anoosheh Sharifan; Associate Professor, Department of Food Science and Technology, Science and Research branch, Islamic Azad University, Tehran, Iran. Tel: +98 9126178388, Email: [email protected]. © 2020 mums.ac.ir All rights reserved. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Rosmarinus Officinalis Essential Oil in Yogurt J N FH Massoud R & Sharifan A Clostridium perfringens in Kashk (19). Probiotic collection. The lyophilized bacteria were yogurt is produced with chamomile EOs at the transferred into a tube containing 10 milliliters concentrations of 0.2% and 0.4%. The probiotic of de Man-Rogosa-Sharpe (MRS) broth and types of yogurt with 0.4% EO constitute the incubated in an anaerobic jar at the temperature largest population of probiotics (B. lactis BB-12) of 37°C for 24 hours. Afterwards, the bacteria (20). were cultivated on the MRS-bile agar (Merck, Rosmarinus officinalis (rosemary) is used in Germany) and anaerobically incubated at the traditional medicine and food products for its temperature of 37°C for 48-72 hours. The full- antimicrobial properties (21). Several grown colonies were harvested to prepare a compounds have been isolated from rosemary, bacterial suspension with the turbidity of the including flavonoids, diterpenes, steroids, and McFarland standard. triterpenes. The major compounds of this plant Probiotic Yogurt Containing the REO with antimicrobial activity are α-pinene, Fresh raw milk (2.5% fat) was obtained from a bornylacetate, camphor, and 1,8-cineole (22). dairy farm (Isfahan, Iran) and heated to the The present study aimed to assess the effects of temperature of 85°C for 20 minutes. Along with the Rosmarinus officinalis essential oil (REO) on Bifidobacterium bifidum, yogurt starter cultures, the pH, microorganism survival, syneresis, Lactobacillus delbrueckii, and Streptococcus rheological parameters, and sensory properties thermophilus (CHR Hansen, Denmark) were of probiotic yogurt during refrigerated storage. added to each container and cooled to the Materials and Methods temperature of 44±1°C. Afterwards, various concentrations of REO (1%, 2%, and 3% [w/v]) Essential Oil Extraction were separately incorporated into the containers Rosmarinus officinalis (English: rosemary, and thoroughly homogenized. At the next stage, Persian: Eklil-Kuhi/Rozmari) was obtained from the yogurt samples were incubated at the a plant shop in Isfahan, Iran. The scientific name temperature of 43±1ºC, and incubation ended of the plant was confirmed by Isfahan University when the samples reached the pH of 4.6 by of Medical Sciences. The leaves of rosemary were storage at the temperature of 4±1°C. The control air-dried in shade at the temperature of 25˚C, and samples were inoculated using both the starters the dried rosemary leaves were hydrodistilled and probiotics with no herbal additives. Each for three hours with 500 milliliters of distilled container was unsealed on days one, seven, 14, water using a Clevenger apparatus. The extracted and 21 for the physiochemical analysis and REO was collected and dried over anhydrous microbial counts. sodium sulfate and stored in sealed glass vials in a refrigerator at the temperature of 4˚C. Chemical Analysis REO Analysis Using Gas Chromatography- Measurement of pH and Acidity Mass Spectrometry The pH values were gauged using a pH meter The chemical composition of the REO was (Swiss, Metrohm 632) at the temperature of 4°C. investigated using a gas chromatograph (Agilent The acidity test was performed based on lactic Technologies, Wilmington, USA) with a mass acid percentage using the titration method, along spectrophotometer (Agilent Technologies, with 0.1 N sodium hydroxide and Wilmington, USA), and an HP-5Ms capillary phenolphthalein (23). column (30.0 m×0.25 mm×0.25 μm) was Syneresis employed for separation. The initial temperature At this stage, 10 grams of yogurt was poured into was 50ºC, which was maintained for two minutes centrifuge tubes and weighed (Wg). The and subsequently elevated to 200ºC at the rate of supernatant (whey) was removed after 3.5ºC/min. After a two-minute pause at the centrifugation at 350 G and the temperature of temperature of 200ºC, the temperature 10°C for 30 minutes (We). Following that, the increased to 280ºC in steps of 7ºC/min. tubes were weighed again, and the syneresis of Primary Culture Preparation the yogurt samples was calculated using the Bifidobacterium bifidum PTCC 1644 was following formula (24): obtained from the Iranian Research Organization % Syneresis = (Wg – We) / Wg × 100 for Science and Technology (IROST) culture J Nutrition Fasting Health. 2020; 8(3): 176-185. 177 Massoud R & Sharifan A J N FH Rosmarinus Officinalis Essential Oil in Yogurt where We is the weight of the whey released (1: Strongly Dislike, 2: Slightly Dislike, 3: Neither from the yogurt, and Wg represents the initial Like nor Dislike, 4: Slightly Like, 5: Strongly Like) weight of the yogurt. (27).