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Carrots (the main source of carotenoids) have multiple nutritional and health benefits. The objectives of this study were to evaluate the compositional, antioxidant, and antimicrobial properties of carrot powder and to examine its effect on the sensory characteristics, chemical properties, and microbial viability of probiotic soft cheese at a rate of 0.2, 0.4, and 0.6%. The carrot was turned into powder before being analyzed and incorporated as an ingredient in making probiotic soft cheese. Probiotic soft cheese was made from buffalo milk. The buffalo milk (∼6.9% fat, 4.4% protein, 9.2% milk solids not fat, and 0.7% ash) was pasteurized at 75 ± 1°C for 5 min and cooled to 40–42°C. The milk was then divided into 4 aliquots. Sodium chloride (local market, Assiut, Egypt) was added at a ratio of 5% followed by starter cultures. The carrot powder (4.5% moisture, 4.8% ash, 2.7% fat, 8.2% protein, 11.9% fibers, and 72.3% carbohydrate) was added at a rate of 0.2, 0.4, and 0.6%, followed by addition of 0.02 g/kg rennet. The cheese was cut again into cubes, pickled in jars filled with whey, and stored for 28 d at 6 ± 1°C. The results of this study illustrated the nutritional and antioxidant properties of carrot powder. Incorporation of carrot powder in probiotic soft cheese affected the moisture and salt content at 0 d. The total bacteria count decreased from 7.5 to 7.3 log cfu/g in the cheese when carrot powder was used at a rate of 0.6%. The reduction of total bacteria count was noticed during the 28 d of storage by adding carrot powder. Furthermore, lactic acid bacteria and Bifidobacterium longum counts elevated with adding carrot powder during the 28 d of storage.
Due to the high nutritional value of food items with added functional ingredients, the demand for those types of foods has increased significantly. The presence of food containing phytochemicals in our daily diet may reduce birth defects, cancer, cardiovascular, and neurodegenerative diseases (
), is associated with reducing the risk of cardiovascular disease and cancer.
Carrot (Daucus carota L.) is a nutritious root vegetable (seasonal crop), which is not available through the year. Drying the carrot could be an efficient way to extend its shelf-life (
). Carrots are known as a multinutritional food source and are rich in natural bioactive compounds, such as phenolics, carotenoids, polyacetylenes, and ascorbic acid (
) to be used as suitable media for the cultivation of probiotics. Strains of Bifidobacterium and Lactobacillus genera are commonly considered under Generally Recognized As Safe status and are used as functional probiotic dairy products (
). Likewise, using tomato powder as an ingredient in processed cheese formulations resulted in better functional properties in the final product with higher antioxidant activity, as well as sensory properties (
). Another study found that addition of aqueous extracts of the Inula britannica flower in making cheese elevated the protein, ash, and total phenolic content of final cheese (
). Furthermore, utilization of basil leaves in Serra da Estrela cheese led to higher antioxidant activity and kept unsaturated fatty acid and protein contents far from deuteriation (
In recent years, several studies emphasized the health benefits of probiotic cheese. To date, no study used carrot powder to fortify probiotic soft cheese. Therefore, this work aimed to evaluate the nutritional and antioxidant properties of carrot powder and to examine the effect of the carrot powder on the compositional and functional characteristics of soft cheese during storage for 28 d.
MATERIALS AND METHODS
No human or animal subjects were used, so this analysis did not require approval by an Institutional Animal Care and Use Committee or Institutional Review Board.
Preparation of Carrot Powder
Carrots were obtained from a local market (Assiut, Egypt) and washed thoroughly with water and cut into thin slices. Those slices were steam blanched for 3 min to inactivate enzymes (pectinase and peroxidase) and elevate the bioavailability of beta-carotene by thermal treatment (
). The slices were then dried in an electric oven at 55°C for 12 h. The dried carrot was then turned into powder using a high speed grinder (DeLonghi). Subsequently, the carrot powder was sterilized at 121°C for 11 min.
Cheese Manufacturing
Lactococcus lactis ssp. lactis ATCC (11454), Lactiplantibacillus plantarum ssp. plantarum (ATCC 14917), Lactococcus lactis ssp. cremoris (ATCC 19257), and Bifidobacterium longum (ATCC 15707) were obtained from the Egyptian Microbial Culture Collections (Cairo Microbiological Resources Center, Faculty of Agriculture, Ain Shams University, Cairo, Egypt). Lactiplantibacillus plantarum ssp. plantarum was activated using anaerobic conditions in sterile skim milk at 37°C for 24 h., while Lactococcus lactis ssp. lactis and Lactococcus lactis ssp. cremoris were activated at 30°C for 24 h. The viable count of the mix of Lactococcus lactis ssp. lactis and Lactococcus lactis ssp. cremoris was 7.5 ± 0.09 log cfu/mL, whereas Lactiplantibacillus plantarum ssp. plantarum was 7.5 ± 0.02 log cfu/mL, and Bifidobacterium longum was 7.6 ± 0.28 log cfu/mL.
Probiotic soft cheese was made from buffalo milk as described in a previous study (
) with some modifications. Fresh buffalo milk (6.93% fat, 4.37% protein, 9.23% milk SNF, and 0.68% ash) was obtained from the Animal Production Farm (Faculty of Agriculture, Assiut University, Assiut, Egypt). The buffalo milk was heated to 75 ± 1°C for 5 min and then cooled to 40–42°C. The milk was then divided into 4 aliquots. Sodium chloride (local market, Assiut, Egypt) was added to each portion at a ratio of 5%, and then the mix of Lactococcus lactis ssp. lactis and Lactococcus lactis ssp. cremoris was added at 2%, followed by the addition of 1% Lactiplantibacillus plantarum ssp. plantarum, and 15% Bifidobacterium longum. The inoculated milk was left for 30 min. The first portion was used as a control, whereas the other 3 portions were supplemented with 0.2, 0.4, and 0.6% carrot powder. Subsequently, rennet (Chr. Hansen's) was added at a rate of 0.02 g/kg. The fermentation was done at 40–42°C until the curd was set. The cheese was then cut and left in cheesecloth to drain for 3 d at 5°C. The cheese was cut again into cubes, pickled in plastic jars filled with whey, and stored for 28 d at 6 ± 1°C. This experiment was repeated 3 times. The yield of cheese samples was calculated as the weight of cheese divided by the weight of milk expressed as a percentage (
Most of the chemicals were obtained from El-Gomhouria Inc. The 2.2-diphenyl-1-picrylhydrazyl (DPPH), Folin-Ciocalteu reagent, and gallic acid were procured from Sigma-Aldrich.
Chemical Composition
Moisture, fat, and total protein (TP) were determined (
) and the results were expressed as milligrams of gallic acid equivalents per 100 g sample (mg of GAE/100 g sample). This test was duplicated on each replicate.
Antioxidant Activity
The antioxidant activity of carrot powder extract was estimated using DPPH scavenging activity (
Comparison of bioactive compounds content, free radical scavenging, and anti-acne inducing bacteria activities of extracts from the mangosteen fruit rind at two stages of maturity.
). This was done in duplicates. As DPPH solution in methanol (0.13 mM) was added to the methanolic extract of carrot powder, the control sample was prepared by mixing methanol and DPPH. Then mixtures were allowed to stand in the dark at room temperature for 30 min. The absorbance of the mixture was recorded at 517 nm by spectrophotometer, and the ability of carrot powder extract to scavenge DPPH radical was calculated as follows:
Gas Chromatography-Mass Spectrometry Analysis
The GC-MS analysis was conducted to analyze volatile and semi-volatile compounds (Department of Analytical Chemistry, Faculty of Science, Assiut University, Assiut, Egypt). The extract was prepared in chloroform as follows: 1 g of carrot powder, 0.1 mL of phosphoric acid (1:1), and 2 mL of chloroform were added. Then it was sonicated for 15 min by ultrasonic, followed by centrifugation (5,009 × g) for 20 min at 15°C. Subsequently, the clear organic layer was separated and injected into GC-MS. The GC-MS analysis was performed using a GC-MS (7890A-5975B) equipped with column DB 5 ms (30 m × 0.250 mm × 0.250 µm). The initial temperature of the GC oven was kept at 60°C and then increased to 120°C at a rate of 10°C/min, followed by a series of continuous temperature increase to 175°C at a rate of 3°C/min, 205°C at a rate of 5°C/min, 210°C at a rate of 0.8°C/min, and finally at 280°C at a rate of 5°C/min. Helium was used as the carrier gas at a flow rate of 0.5 mL/min. Volatiles were identified using the Wiley registry, 11th ed, and the NIST 2017 mass spectral library. Data are expressed as the percentage of the total GC area. Duplicate samples were tested for each replicate.
Microbiological Analysis
Antimicrobial Activity
The antimicrobial activity of the carrot powder was tested against 6 bacterial strains (Bacillus cereus AUMC no. B-52, Escherichia coli AUMC no. B-53, Micrococcus luteus AUMC no. B-112, Pseudomonas aeruginosa AUMC no. B-73, Serratia marcescens AUMC no. B-55, and Staphylococcus aureus AUMC no. B-54) obtained from Mycological Center, Faculty of Science, Assiut University, Assiut, Egypt. Bacterial strains were individually inoculated in a nutrient broth medium for 48 h to prepare inoculum. Sterile plastic Petri plates (10 cm diameter) and nutrient agar medium were used in the bioassay (
). After media solidification, a sterile cork borer was used to cut 5-mm diameter cavities in the solidified agar (4 cavities per plate). Carrot powder methanolic extract was pipetted in the cavities (20 µL per cavity). Plates were incubated at 28°C for 48 h, and the diameter of the inhibition zone around cavities was measured and reported in mm (
Bacterial counts were performed in cheese samples at 0 and 7, 14, 21, and 28 d. Total bacteria count (TBC) was enumerated on a nutrient agar medium (Plate Count Agar, HiMedia Laboratories Pvt. Ltd.) after incubation at 37°C for 48 h (
). Lactic acid bacteria (LAB) counts were enumerated on a de Man, Rogosa, and Sharpe agar medium (Neogen culture media) after incubation anaerobically at 37°C for 48 h. Bifidobacterium counts were enumerated on a modified de Man, Rogosa, and Sharpe medium (
) was used for yeast enumeration. Two samples were analyzed for microbiological analyses in each replicate at each time point.
Sensory Analyses
Cheese samples were judged by 10 staff members of the Dairy Science Department at Assiut University for sensory analyses. Flavor (50 points), body and texture (40 points), and color and appearance (10 points) were evaluated at 0 and 28 d of storage to have 100 points total (
One-way (treatment) and 2-way (treatment and time) ANOVA were tested using SPSS software (version 16.0 for Windows, SPSS Inc.). When significant differences (P < 0.05) were noticed among means, Duncan's multiple comparison test was used for mean difference testing.
RESULTS AND DISCUSSION
Composition of Carrot Powder
The chemical composition of carrot powder samples is shown in Table 1. The moisture content of carrot powder was 4.5%, whereas ash, fat, TP, and fiber contents were 4.80, 2.75, 8.25, and 11.94% on a dry basis, respectively. It was found that ash, fat, TP, and fiber in carrot powder were approximately 6.80, 2.90, 9.20, and 7.20%, respectively, on a dry basis (
). Another study stated that carrot samples have moisture content of 11.70%, whereas ash, fat, TP, and fiber contents were approximately 13.40, 5.40, 10.40, and 13.70% on a dry basis, respectively (
). The total carbohydrate content of carrot powder in current research recorded was around 72.30%, while the caloric value was 346.8 kcal/100 g on a dry basis. Our results were in agreement with those reported by
Potassium, phosphorus, calcium, sodium, magnesium, iron, and zinc contents in carrot powder are illustrated in Table 1. In the present study, potassium, phosphorus, calcium, sodium, magnesium, iron, and zinc were approximately 532.7, 199.3, 880.0, 615.0, 171.7, 20.7, and 3.4 mg/100 g on a dry basis, respectively. Similar findings were exemplified by
, as they found that zinc content in carrots was 3.2 mg/100 g on a dry basis. Moreover, it was reported that calcium, phosphorus, and iron contents in carrot pulp waste were 314.95, 317.77, and 12.65 mg/100 g on a dry basis, respectively (
Vitamin C, β-carotene, vitamin A, total phenolics, and antioxidant activity of carrot powder samples are presented in Table 2. Data showed that vitamin C content was 50.0 mg/100 g on a dry basis. It was reported that ascorbic acid was 8.0 mg/100 g of fresh orange-colored carrots (
). Furthermore, in the current study, β-carotene content was 123.0 mg/100 g on a dry basis. However, another study observed lower content of β-carotene in carrot powder at a rate of 1,154.20 µg/g or 115.42 mg/100 g (
) when compared with our findings. Such differences could be attributed to the variety and environmental factors. Furthermore, The retinol equivalent of carrot powder (Table 2) was about 20,500 (RE/100 g), which was obtained using the standard conversion formula. Likewise, others studies examined 5 groups of fresh carrots and found that the β-carotene and vitamin A contents were 12,300 µg/100 g and 2,054.1 RE/100 g, respectively (
The total phenolics content (Table 2) in carrot powder was 203.6 mg/100 g on a dry basis sample, whereas it was reported that the range of total phenolic content in 15 varieties of orange carrot ranged from 18.7 to 33.8 mg/100 g as gallic acid equivalents on a fresh weight basis (
The antioxidant activity of carrot powder (determined by DPPH scavenging activity) was 64.45%. Our value is higher than the values reported in the study conducted by
estimated radical scavenging activity using a stable DPPH radical. They found that the DPPH ranged from 3.5 to 13.7% in 15 varieties of orange carrot extracts (on a fresh weight basis). Moreover, the importance of carotenoids (which are located in orange carrots) was referred to as a valuable antioxidant component that can neutralize the effect of free radicals (
The GC-MS of compounds was carried out in chloroform extract of carrot powder. The GC-MS in our study detected 43 compounds as shown in Table 3; however, a previous study detected 18 compounds using the same methodology (
). The retention time and value (% concentration) in Table 3 indicated that the first setup peak was tetrahydro-2-(3-methyltricyclo[2.2.1.0(2,6)] hept-3-yl)oxyl-2H-pyran. The most volatile compounds were butyl-9,12-octadecadienoate; glycerol 1-palmitate, O-cyanobenzaldehyde; and 7.7',8,8',11,11',12,12',15,15'-decahydro-beta,psi-carotene. Moreover, the data in Table 3 detected terpenoids in carrot powder samples, which were alpha-terpinene and (E)-geranylacetone (monoterpenes); caryophyllene, trans-gamma-bisabolene and 3β-hydroxy-8-oxo-6.β.H.7.α.H, 11.β. H-germacran-4(14),9(10)-dien (sesquiterpene); phytane (diterpenes); and squalene (triterpenes). Our data were similar to previous studies, which concluded that the terpenes were the most important volatiles identified in carrots (especially in red and orange carrots;
Identification of volatile organic compounds (VOCs) in different colour carrot (Daucus carota L.) cultivars using static headspace/gas chromatography/mass spectrometry.
). A different study examined the volatile compounds in carrot juice from 12 different varieties and found alpha-terpinene (2.51, 2.69), geranylacetone (2.06, 2.69), caryophyllene (3.94, 3.53), and (E)-gamma-bisabolene (4.05, 4.34) in fresh and processed carrots, respectively (
). Table 3 reveals that trans-beta-ionone recorded 3.78%, which is considered as a transconfiguration of β-ionone (cyclic terpenoid required for vitamin A synthesis;
), whereas cis-p-mentha-2,8-dien-1-ol (monocyclic terpene) found at a concentration of 0.19%. Additionally, many terpenes are known to have antimicrobial, anticarcinogenic, and antidepressant activities, and they are associated with reducing plasma glucose levels in diabetes mellitus rats (
Myers, C. E., J. Trepel, E. Sausville, D. Samid, A. Miller, and G. Curt. 1997. Monoterpenes, sesquiterpenes and diterpenes as cancer therapy. US Pat. No. 5,602,184.
Comparative study on the free radical scavenging mechanism exerted by geraniol and geranylacetone using the combined experimental and theoretical approach.
). Moreover, squalene is considered a precursor of steroids, and it stimulates the decrease of total cholesterol, LDL cholesterol, and triacylglycerol levels in hypercholesterolemic patients (
). However, Table 3 shows that 5,6,7,7a-tetrahydro-4,4,7a-trimethyl-2(4H) benzofuranone and diethylmalonic acid monochloride tetrahydro furfuryl ester recorded 1.68 and 0.95%, respectively, which were related to thermal processing in dehydrated carrots (
). Ethyl-8H-naphtho[2', 1:5,6]pyrano[4,3-b] quinoline-11-carboxylate and 6,8-dichloro-2-[4-chlorophenyl]-4-bromoacetyl quinoline in Table 3 recorded 1.78 and 1.01%, respectively, and belong to a group of quinoline derivatives, which are considered important fragrance substances (
). Also, Table 3 indicates several fatty acids and their esters in carrot powder samples, similar to 9,12-octadecadienoic acid (z,z)-,2(acetyloxy)-1-[(acetyloxy)methyl] ethyl ester, tetradecanoic acid, 1-methylethyl ester, hexadecanoic acid methyl ester, hexadecanoic acid, ethyl ester, trans-delta(sup 9)-octadecenoic acid, oleic acid, 9-octadecenoic acid (Z)-, eicosyl ester, octadecanoic acid, methyl ester, 3-methyl-2,6-dioxo-4-hexenoic acid, delta 9-cis-oleic acid, butyl 9,12-octadecadienoate and (6Z)-6-octadecenoic acid. While the compound 6-fluoro-7-dehydrocholesterol was detected (0.30%) in carrot powder samples (Table 3), it also plays an important role in the synthesizing of vitamin D (Miguel et al., 2019). Data in Table 3 revealed that falcarinol recorded 2.01%. Also, it was found that carrot extracts contain different amounts of falcarinol, falcarindiol, and falcarindiol 3-acetate (
Extraction and identification of bioactive compounds (eicosane and dibutyl phthalate) produced by Streptomyces strain KX852460 for the biological control of Rhizoctonia solani AG-3 strain KX852461 to control target spot disease in tobacco leaf.
). In contrast, Table 3 shows that carrot powder contains 1-(4-bromobutyl)-2-piperidinone, which has a strong effect on the pathogenic microorganisms (
), whereas estra-1,3,5(10)-trien-17β-ol in our research recorded 2.93%, which has antitumor, anti-inflammatory, antioxidant, and antimicrobial activities (
The antimicrobial potential of carrot powder extracts against 6 pathogens was examined in terms of zone inhibition of bacterial growth, and the results are exemplified in Table 4. The growth inhibition zone was measured for 50 µL of carrot powder methanolic extracts, and the zones were in the range of 7.0–10.0 mm. The maximum zone formation was against Pseudomonas aeruginosa. According to a previous study (
), it was observed that the growth inhibition zone of the methanolic extracts of carrot peel for 4 bacteria (Shigella flexneri, Escherichia coli, Staphylococcus aureus, and Klebsiella pneumonia) ranged from 12 to 14 mm. These differences in zone inhibition of carrot extracts could be attributed to the variation in sample extract concentrations.
Table 4Antimicrobial activity ± SD of carrot powder methanolic extract
Figure 1 demonstrates the cheese yield of probiotic soft cheese. The cheese yield ranged from 18.2 to 20.5%. These results were lower than the yield of fresh soft cheeses made from cow's milk with different systems (monoculture system and intensive silvopastoral system in different seasons;
). According to Figure 1, the carrot addition in probiotic soft cheese samples reflected a significant (P < 0.05) increase in cheese yield. This increase in cheese yield could be associated with the presence of fiber content in carrot powder, containing hydroxyl groups that interact with the hydrogen bonds of water (
reported that low cheese yield might be caused by lower moisture content in the cheese.
Figure 1Cheese yield (%) of probiotic soft cheese supplemented with carrot powder. C = probiotic soft cheese without any carrot; T1 = probiotic soft cheese with 0.2% carrot powder; T2 = probiotic soft cheese with 0.4% carrot powder; T3 = probiotic soft cheese with 0.6% carrot powder. Means within treatments not sharing a common letter (a, b) are different (P < 0.05). Values shown are mean ± SD.
Sensory evaluation results for fresh cheese and after 28 d of storage are shown in Table 5 and Figure 2. According to Table 5, probiotic cheese with 0.2% carrot powder recorded the highest values in all studied parameters after 28 d, but this increase was not significant (P > 0.05). Carrot addition enhances the flavor due to its content of terpenoids and sugars, which are responsible for carrot flavor (
). Although we observed an increase in the additional percentage of carrot powder during cheese making to 0.6%, body and texture parameters decreased which resulted in holes and increased firmness in the final cheese. In terms of color and appearance, T3 (probiotic cheese with 0.6% carrot powder) had a slight orange color. This observation of color was reported in another study (
). With the increase in the storage duration and ripening of cheese samples, we observed an increase in the overall sensory characteristics of all cheese samples as illustrated in Table 5, which was similar to another report (
). They noticed enhancement of flavor, body, and texture of low-fat Feta cheeses after 30 d of storage at 4°C. Table 5 shows that we observed no significant differences between all cheese samples in all parameters after 28 d of storage, except for sample T3 which had the lowest (P < 0.05) color and appearance. The total score of the sensory evaluation is presented in Figure 2. Sample T1 (probiotic cheese with 0.2% carrot powder) had the highest overall score (P < 0.05) at the beginning of the ripening, whereas we observed no significant differences in overall score between all cheese samples after 28 d of storage.
Table 5Sensory evaluation of probiotic soft cheese supplemented with carrot powder; values shown are mean ± SD
Figure 2Total scores of organoleptic properties of probiotic soft cheese supplemented with carrot powder. C = probiotic soft cheese without any carrot; T1 = probiotic soft cheese with 0.2% carrot powder; T2 = probiotic soft cheese with 0.4% carrot powder; T3 = probiotic soft cheese with 0.6% carrot powder. Means within treatments not sharing a common letter (a, b) are different (P < 0.05). Values shown are mean ± SD.
The protein content of probiotic soft cheese is revealed in Table 6. The TP was calculated in fresh cheese samples by multiplying nitrogen content by 6.38. The TP was 24.84, 27.62, 27.67, and 31.26% in the control, T1, T2, and T3 cheese on a dry basis, respectively. These results reflected the enhancement of protein levels after carrot powder addition. It was found that the protein content in fresh soft cheeses made from cow milk ranged from 32.7 to 36.4% on a dry basis (
How three adventitious lactic acid bacteria affect proteolysis and organic acid production in model Portuguese cheeses manufactured from several milk sources and two alternative coagulants.
). Additionally, we observed a trend of decreasing SN values of fresh cheese samples at 0 d with an elevation in carrot powder concentration. This could be due to the effect of carrot powder on the rennet in the curd (keeping it trapped). referring to the curd ability to trap chymosin (
). In our study, at 28 d of ripening, SN content increased in all samples, while others found that SN contents in soft ultrafiltrate and control cheese samples at 21 d of ripening recorded higher values (1.41 and 1.08%, respectively;
Treatment: control = probiotic soft cheese without any carrot; T1 = probiotic soft cheese with 0.2% carrot powder; T2 = probiotic soft cheese with 0.4% carrot powder; T3 = probiotic soft cheese with 0.6% carrot powder. TP = total protein; SN = soluble nitrogen.
Means in the same column within the same period not sharing a common superscript are different (P < 0.05).
± 0.00
a–d Means in the same column within the same period not sharing a common superscript are different (P < 0.05).
1 Treatment: control = probiotic soft cheese without any carrot; T1 = probiotic soft cheese with 0.2% carrot powder; T2 = probiotic soft cheese with 0.4% carrot powder; T3 = probiotic soft cheese with 0.6% carrot powder. TP = total protein; SN = soluble nitrogen.
2 TP on a dry basis; TP = nitrogen content × 6.38.
found that NPN values after 1 d of ripening were 0.30 and 0.21% in soft ultrafiltrate and control cheese samples, respectively. The NPN values revealed the capability of microbial origin enzymes to degrade large peptides (which are released by the rennet) and produced small peptides, free amino acids, and ammonia nitrogen (
). Table 6 shows that the addition of carrot powder contributed to secondary proteolysis after 28 d of storage; however, this addition decreased the NPN nonsignificantly. These results may be attributed to the inhibition effect of carrot powder on proteolytic bacteria.
Figure 3 shows the ripening extension index in cheese made with carrot powder. The ripening extension index ranged from 25.41 to 36.58% at 0 d, with the control sample being the highest (P < 0.05) in the ripening extension index. Similar results were reported by
. After 28 d of ripening, the extension index increased at a slow rate, which might be attributed to the low temperature during storage, and this, in turn, reduce the rate of protein hydrolysis (
found that the ripening extension index values in soft ultrafiltrate and control cheese samples after 21 d of ripening were 48.5 and 41.1%, respectively.
Figure 3Ripening extension index of probiotic soft cheese supplemented with carrot powder. SN%TN = soluble nitrogen as a percentage of total nitrogen; C = probiotic soft cheese without any carrot; T1 = probiotic soft cheese with 0.2% carrot powder; T2 = probiotic soft cheese with 0.4% carrot powder; T3 = probiotic soft cheese with 0.6% carrot powder. Means within treatments not sharing a common letter (a, b) are different (P < 0.05). Values shown are mean ± SD.
However, Figure 4 shows the ripening depth index in all cheese samples at 0 d and after 28 d of storage. Lower values of the ripening depth index were found by
). Furthermore, the addition of carrot powder caused a decrease in the ripening depth index. Although we observed the ability of carrot addition to increase the numbers of LAB (which release enzymes and produce NPN), this addition had a small influence on proteolysis due to the low ability of Lactiplantibacillus plantarum ssp. plantarum in protein hydrolysis (
The effects of Lactobacillus plantarum combined with inulin on the physicochemical properties and sensory acceptance of low-fat cheddar cheese during ripening.
How three adventitious lactic acid bacteria affect proteolysis and organic acid production in model Portuguese cheeses manufactured from several milk sources and two alternative coagulants.
Figure 4Ripening depth index of probiotic soft cheese samples supplemented with carrot powder. NPN%TN = nonprotein nitrogen as a percentage of total nitrogen; C = probiotic soft cheese without any carrot; T1 = probiotic soft cheese with 0.2% carrot powder; T2 = probiotic soft cheese with 0.4% carrot powder; T3 = probiotic soft cheese with 0.6% carrot powder. Means within treatments not sharing a common letter (a, b) are different (P < 0.05). Values shown are mean ± SD.
Table 7 exemplifies that the moisture content of probiotic cheese supplemented with carrot powder increased significantly (P < 0.05) by elevating the concentration of carrot addition. This increase could be due to the enhancement of water holding capacity (
). We observed a trend in decreasing water content during storage so the control sample had the lowest moisture content (51.66%) after 28 d of storage. Similar results were noticed by others, as they found that the moisture content decreased in cheese samples during storage (
). In contrast, Table 7 reveals that cheeses treated with carrot powder had higher moisture contents and lower fat (especially in sample T3). Similar findings were reported by other researchers when they treated soft white cheese with cranberry fruit extract (
). After 28 d of storage, fat content increased in cheese treated with carrot powder (Table 7) due to the increment of dry matter. Elevating the content of carrot powder to 0.6% during the making of probiotic soft cheese had a significant effect (P < 0.05) on salt contents, as sample T3 recorded the highest ash value (4.09%). These results might be related to the increment of moisture content with carrot addition, which increases the cheese's ability to absorb more salt (
Rheological, textural, microstructural, and sensory impact of exopolysaccharide-producing Lactobacillus plantarum isolated from camel milk on low-fat akawi cheese.
found that salt content ranged from 4.91 to 5.03% in white cheeses, which were manufactured with different probiotic bacteria. Even though throughout the ripening period, salt content fluctuated due to the diffusion of salt between whey and cheese samples (
How three adventitious lactic acid bacteria affect proteolysis and organic acid production in model Portuguese cheeses manufactured from several milk sources and two alternative coagulants.
), we observed no significant differences (P > 0.05) between all fresh cheese samples in titratable acidity. By increasing the storage period, the control cheese samples had a higher significant (P < 0.05) titratable acidity than the cheese samples treated with carrot powder. These results agreed with the findings of several studies (
reported a rise in TBC in soft white cheese during the storage period. However, our study showed a significant reduction (P < 0.05) of TBC at 0 d of storage for samples T2 and T3 containing carrot concentrations of 0.4 and 0.6%, respectively, compared with the control sample. The decline of TBC in cheese made with carrot powder revealed the preservative effect of carrot used in probiotic soft cheese. The current study also evaluated the growth of LAB and Bifidobacterium species during the storage period (Table 8) and observed a significant (P < 0.05) increase in both probiotic cultures during the storage of samples T2 and T3. Because LAB are known to release bacteriocins, the reduction in TBC counts can be a result of the increase in LAB (
). Lactic acid bacteria recorded their highest number in sample T3 after 21 d of storage, followed by a decrease from 8.77 to 8.47 log cfu/g (Table 8). This decline may be due to the consumption of nutrients and lactic acid production by LAB, which affected their growth and numbers (
), whereas in our study, LAB and Bifidobacterium longum counts were 8.47 and 9.40 log cfu/g in T3 after 28 d of ripening. These results indicate that probiotic bacteria can survive in the final cheese with carrot powder addition during ripening, as carrot powder induced and maintained the growth of probiotic bacteria. However, proteolytic bacteria appeared in all cheese samples after 14 d of storage, followed by a decrease in counts by the end of storage. Similar growth trends of proteolytic and lipolytic bacteria were reported (
). Furthermore, elevating the carrot powder concentration in probiotic cheese samples resulted in a decrease in proteolytic counts, while no lipolytic bacteria were observed. However, psychotropic counts were observed after 28 d of storage for all samples. Test T3 recorded the lowest psychotropic count. The results of yeast and mold analysis revealed the growth of molds in the control samples only after 21 d of storage, whereas yeast counts were not detected in any of the cheese samples during storage for 28 d.
Table 8Mean (n = 3) ± SD microbiological characteristics (log cfu/g) of probiotic soft cheese supplemented with carrot powder during storage for 28 d
Treatment: control = probiotic soft cheese without any carrot; T1 = probiotic soft cheese with 0.2% carrot powder; T2 = probiotic soft cheese with 0.4% carrot powder; T3 = probiotic soft cheese with 0.6% carrot powder. ND = not detected.
Results of the present study indicated that carrot powder is a good source of nutrients, such as minerals, β-carotene, lycopene, phenolic compounds, and flavonoids. We also found that carrot powder enhanced the antimicrobial and antioxidative value of the probiotic cheese cheese. Using carrot powder as a functional ingredient in probiotic soft cheese induces the growth of probiotic bacteria, and therefore can be used as a potential prebiotic to improve the viability of probiotic bacteria in various food applications similar to white cheese.
ACKNOWLEDGMENTS
This study received no external funding. The authors thank Adel Tammam (Professor of Dairy Science at the Dairy Science Department, Faculty of Agriculture, Assiut University, Egypt) for his guidance and support. The authors have not stated any conflicts of interest.
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Khozirah S.
Umi Kalsom Y.
Antioxidant and nitric oxide inhibition activities of selected Malay traditional vegetables.
Extraction and identification of bioactive compounds (eicosane and dibutyl phthalate) produced by Streptomyces strain KX852460 for the biological control of Rhizoctonia solani AG-3 strain KX852461 to control target spot disease in tobacco leaf.
Rheological, textural, microstructural, and sensory impact of exopolysaccharide-producing Lactobacillus plantarum isolated from camel milk on low-fat akawi cheese.
Identification of volatile organic compounds (VOCs) in different colour carrot (Daucus carota L.) cultivars using static headspace/gas chromatography/mass spectrometry.
Myers, C. E., J. Trepel, E. Sausville, D. Samid, A. Miller, and G. Curt. 1997. Monoterpenes, sesquiterpenes and diterpenes as cancer therapy. US Pat. No. 5,602,184.
How three adventitious lactic acid bacteria affect proteolysis and organic acid production in model Portuguese cheeses manufactured from several milk sources and two alternative coagulants.
Comparison of bioactive compounds content, free radical scavenging, and anti-acne inducing bacteria activities of extracts from the mangosteen fruit rind at two stages of maturity.
Comparative study on the free radical scavenging mechanism exerted by geraniol and geranylacetone using the combined experimental and theoretical approach.
The effects of Lactobacillus plantarum combined with inulin on the physicochemical properties and sensory acceptance of low-fat cheddar cheese during ripening.
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