Rahman Yousefi; Mohammadreza Pourghayoumi; Seyyed Samih Marashi; Ali Ghasemi
Abstract
AbstractIntroduction: Date palm (Phoenix dactylifera) is one of the most important horticultural products in arid and semi-arid regions of Iran. In the recent years salinity stress negatively affected date fruit quality. The silicon is one of the useful nutrients that plays an important role in the growth ...
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AbstractIntroduction: Date palm (Phoenix dactylifera) is one of the most important horticultural products in arid and semi-arid regions of Iran. In the recent years salinity stress negatively affected date fruit quality. The silicon is one of the useful nutrients that plays an important role in the growth and development of plants. Silicon reduces the adverse effects of abiotic stresses such as drought and salinity by affecting the leaf and stem growth, and other plant mechanisms. Therefore, the aim of this research is to investigate the effect of foliar application of silicon on some qualitative characteristics and nutrient elements contents of date fruit that grown under high soil salinity conditions.Materials and Methods: This research was conducted in a randomized complete block design with 7 treatments and 3 replicates in two consecutive years. Silicon foliar spray treatments contains, without application of foliar spraying (T1), foliar spraying with a concentration of 0.1% in two stages (T2), foliar spraying with a concentration of 0.1% in three stages (T3), foliar spraying with a concentration of 0.2% in two stages (T4), foliar spraying with a concentration of 0.2% in three stages (T5), foliar spraying with a concentration of 0.3% in two stages (T6) and foliar spraying with a concentration of 0.3% in three stages (T7). Fruit quality characteristics including total soluble solids (TSS), acidity (TA), pH and total sugar percentage and concentration of fruit nutrients were measured and statistically analyzed.Results and Discussion: Foliar application of silicon fertilizer significantly increased TSS of ‘Barhee’ date fruits while it decreased pH of fruit juice. Fruit acidity and total sugar were not affected significantly by foliar application of silicon. The application of silicon significantly increased the contents of potassium, calcium, iron and zinc in date fruit, but it had no significant effect on the concentration of phosphorus in the fruit. Overall, foliar application of silicon fertilizer with a concentration of 0.3% in two stages (three weeks before pollination and at the end of the Hababook stage) improved quality characteristics and the nutrient elements of ‘Barhee’ date fruit under high soil salinity conditions.Keywords: Acidity, Iron, Potassium, Total soluble solids, Total sugar
Food Biotechnology
Fatemeh Barmak; Mohammad Bagher Habibi Najafi; Reza Hajimohammadi Farimani; Mohammad Reza Edalatian Dovom
Abstract
Introduction: One of the most important factors in producing yogurt is choosing the right starter. Native isolates of any country are among the genetic resources of that country, which play a major role in the production and development of the organoleptic properties of fermented products. Therefore, ...
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Introduction: One of the most important factors in producing yogurt is choosing the right starter. Native isolates of any country are among the genetic resources of that country, which play a major role in the production and development of the organoleptic properties of fermented products. Therefore, it seems necessary to study the industrial applications of native isolates. In this study, the production of yogurt was investigated by using native starter isolates from traditional Khorasan yogurts and its comparison with yogurts produced with two types of commercial starters. Materials and methods: Six strains of Streptococcus thermophilus and three strains of Lactobacillus delbrueckii subsp. Bulgaricus isolated from traditional Khorasan yogurts were selected. The proteolytic activity of Streptococcus thermophilus strains was determined according to the method of Erkus et al(2012) and the proteolytic activity of Lactobacillus delbrueckii subsp. Bulgaricus was determined according to the method of Nespolo et al.(2010). Milk acidification activity byall examined strains was evaluated according to the method of Erkus et al.(2012). The production property of gamma-aminobutyric acid of native isolates was also evaluated using the method of Lacroix et al. (2013). Yogurt was produced using commercial starters and native isolates. Acidity and pH were measured according to Iranian National Standard No. 2852. Synersis of yogurt samples was measured using centrifugation according to Çelik (2007) method. In order to measure textural properties, a combination of backward extrusion techniques and Texture Profile Analysis (TPA) was used (Yang et al, 2010). Sensory characteristics of yogurt samples were evaluated by 20 panelists using five-point hedonic scale. This study was conducted based on factorial experiment using a completely randomized design. Statistical analysis of data was performed using Minitab Statistical Software (version 17) and ANOVA. Comparison of means was performed using Tukey’s test at the significant level (p < 0.05). Results and discussion: The results of proteolytic activity of Lactobacillus delbrueckii subsp. Bulgaricus showed that the L3 code was weaker than the other two strains. All Streptococcus thermophilus strains were positive protease. All Streptococcus thermophilus strains of the study decreased the pH of the milk to 4.6 in less than five hours, and Streptococcus thermophilus strain S6 code, as the fastest acid producer, decreased the pH of the milk to 4.6within 3 and half hours (Figure 2). The results of GABA production showed that among the streptococcus thermophilus strains, S1, S5 and S6 codes had distinct blue discoloration. Among the Lactobacillus strains, except the L3 strain, two other strains produced green color. Of the 18 samples of the yoghurt, S5L2 and S2L2 samples showed the highest decrease in pH and increased in acidity compared to other samples after being stored refrigerated overnight (P <0.05). The other samples had the same pH and acidity changes as the control samples after overnight refrigeration. The results show the ability of yogurt producion by native starters to compete with those produced by commercial starters in terms of technological characteristics. Thus, samples with codes S2L2, S3L1, S3L2, and S1L1 showed less Synersis of yogurt than commercial starters. This decrease in the Synersis of yogurt might due to the possibility of exopolysaccharide production by these strains. Textural characteristics of yogurt samples were the hardness of the samples in the range of 3 to 4 N, which was significantly different (P <0.05). The lowest hardness was observed for the S3L3, which can be attributed to the poor proteolytic activity of the strain. L3, S6L2, S3L2 and S2L2 had the highest hardness compared to other compounds and control samples (P <0.05). This differences in the hardness of the samples can be attributed to the possible production of some metabolites by the strains. There was no statistically significant difference in the adhesion properties of the samples (p <0.05). Considering the sensory evaluation scores, it was found that in all respects, S3L3 had the lowest score among the other samples (P <0.05). This was in good correlation with the results of the textural properties of the test. Therefore, this compound was eliminated compared to the control samples. Finally, considering the proteolytic behavior of the strains and the ability to produce acid and GABA, as well as the sensory, rheological and physicochemical properties of 18 samples in comparison to the two control samples, Streptococcus thermophilus strains with codes S4, S2, S5, S1, S6, and Lactobacillus delbrueckii subsp. Bulgaricus strains with codes L1 and L2 have the potential to be used as commercial starters in the form of compounds S1L1, S2L2, S5L1, S6L2, S4L2.
Marzieh Salami; Massoumeh Mehraban Sangatash; Ahmad Ehtiati
Abstract
Introduction: Yogurt is one of the most popular dairy products, which has numerous health effects on human body. Dietary fiber consumption is highly recommended. Fibers are highly hydrophilic and absorb water into the digestive track, increase the volume of food and thereby facilitating excretion. These ...
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Introduction: Yogurt is one of the most popular dairy products, which has numerous health effects on human body. Dietary fiber consumption is highly recommended. Fibers are highly hydrophilic and absorb water into the digestive track, increase the volume of food and thereby facilitating excretion. These are some health benefits of these compounds. Consumption of fiber-containing yogurt can be helpful for people who suffer from cardiovascular diseases, hypertension, diabetes and obesity. Zucchini, as a vegetable, is a source of fibers and due to its health-promoting effects, can be used in dairy products. The aim of this study is to evaluate the effects of different levels of dried zucchini on stirred yogurt during storage. Materials and Methods: The raw materials for the production of the functional yogurt were zucchini, milk, skim milk powder, whey powder, hydrocolloids stabilizer compound and starter culture. Fresh zucchini was hot-air dried at 70 °C for 7 hours. Two forms of the dried zucchini (powder and granule) were added to fresh yogurt at levels of 0.7, 1.4, and 2%. The samples were then tested on days 1, 5, 10 and 15 for acidity (titration method), pH, texture stiffness (back extrusion), syneresis, color (using image processing) and sensory properties, including color, taste, aroma, consistency, mouthfeel and overall acceptance. The experiments were triplicated and analysis of variance was performed using Minitab software at 95% confidence interval. For the significant variables, the means were compared using LSD method. Graphs were drawn using MS-Excel. Results and Discussion: The effects of zucchini form and level of addition, storage time and interaction of these variables were significant (P<0.05) on the titratable acidity, pH and firmness. Over time, pH decreased and acidity increased, which was related to the starter activity and acid production. Due to the use of stabilizer and whey protein, all samples showed no syneresis. The firmness of the samples containing zucchini powder was higher than that of the granule- (P<0.05). This might be related to the homogeneous structure of zucchini fiber, which increased water absorption regarding its lower particle size. Firmness increased from day one to day five, due to the high water absorption of hydrocolloids that bind to free water present in the yogurt structure. The presence of milk proteins and whey protein concentrate in the yogurt formula enhanced crosslinking in the particle gel network, which resulted in a stronger gel structure. During longer storage, firmness decreased from day 5 to day 10, probably was due to the increased pH, which affects the proteins and polysaccharides interaction. The effects of the form and level of zucchini and the interaction between these variables were significant (p <0.05) on the changes in L*, a*, and b*. The L* and a* values which were higher in the samples containing zucchini granules than in the zucchini powder, most probably due to the smaller particle sizes of the powder compared with the granules, causing the number of the powder particles per unit volume to be larger and the powder-containing samples to become darker. In terms of the level of addition, L* increased as the zucchini level rose to 1.4% and then declined to 2%. The sensory properties of all samples were significantly affected by the storage time (P<0.05). With increase in the storage time, all the sensory scores increased. The highest overall acceptance score belonged to the yogurt sample containing 1.4% granule on the 10th day of storage. Overall, zucchini is a good candidate for yogurt fortification. This incorporation results in a greenish yogurt with more health functionalities. The highest overall acceptance score was obtained for the yogurt containing 1.4% zucchini granule on the 10th day of storage (best consumption date) and the results showed acceptable firmness for this sample.
Neda Derakhshan; Ali Akbar Shokouhian; Bahram Fathi achachelooee
Abstract
Introduction: Peach fruit is considered to be a part of the fragrance fruits in terms of respiratory behavior, which is why it quickly becomes corrosive at normal temperature. Shelf life of peach is limited because of weight loss due to water loss and physiological abnormalities such as browning and ...
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Introduction: Peach fruit is considered to be a part of the fragrance fruits in terms of respiratory behavior, which is why it quickly becomes corrosive at normal temperature. Shelf life of peach is limited because of weight loss due to water loss and physiological abnormalities such as browning and tissue alteration. The Aloe Vera gel is a polyester coating and has an elastic property that is easily soluble in water and covers the entire area around the product to a similar extent. This gel acts as a protective layer on the product and protects the cells below the protective layer against mechanical damage and also prevents the loss of juices. Polyamines are a group of low-molecular-weight, naturally-occurring compounds with linear nitrogen groups found in almost all organisms and play a role in a wide range of physiological processes in plants, animals and microorganisms. The purpose of this experiment was to investigate the effect of Putrescine and Aloe Vera gel on the prolongation of the post-harvest life of peach fruit.
Materials and methods: Peach fruits (Prunus persica L.), the redtop cultivar at commercial maturing stage, when 80-50% of the fruits were painted, Harvested from the gardens of Moghan Agro Industry & Industry Co., located in Pars Abad city and after transferring to the laboratory, coating treatments as factorial based on completely randomized design with coating treatments in four levels of Putrescine (0, 2, 4, and 6 milli molar) and Aloe-vera gel treatments in four levels (0%, 15%, 30%, and 45%) in three time periods (15, 30 and 45 days) and three replicates with total of 144 experimental units was carried out. The fruits at -1° C and humidity of 95-90% were kept in cold storage. The pH of the juice were measured by a Digital pH Meter, soluble solids at room temperature was read by hand-made refractometer on a graded column. To measure total acid, titration was performed using 0.1% sodium hydroxide solution and the results were expressed in grams of malic acid in 100 grams of fresh weight. Measurement of vitamin C was done by titration with Decolor phenol Indole Phenol and Meta phosphoric acid and its amount expressed as mg of ascorbic acid in 100 grams of sample. The total phenol content was measured by the Folin- Sioculto method. The acetone method was used to measure carotenoid. Flavonoids were measured by acid ethanol method. The data of this study were analyzed using SPSS (9.1.3) and comparison of mean of treatments with LSD-test at probability level of 5%. Charts were also drawn using Microsoft Excel software.
Results & Discussion: Based on the analysis of variance table, the triple effects of Putrescine, aloe vera and time treatments in all indices had a significant effect at 1% probability level. Analysis of variance showed the lowest pH at combined treatment of 6 mM putrescine and 30% Aloe-vera gel. Also, the most titratable acidity was observed at combined treatment of 6 mM putrescine and 15% Aloe-vera gel and the most total soluble solids was observed at combined treatment of 2 mM and 45% Aloe-vera gel. Highest levels of vitamin C were observed at combined treatment of different levels of Aloe-vera gels at 6 mM putrescine. The most carotenoid levels was for combined treatment of 6 mM putrescine and 30% Aloe-vera gel and the most flavonoids was for combined treatments of 6 mM putrescine and 45% Aloe-vera gel. The pH peach juice increased during storage, due to the breakdown and decomposition of organic acids in the respiration process. The organic acids during storage are low due to their consumption during respiration and have a downward trend. The amount of soluble solids in fragrance fruits, such as peaches, increases during storage, when using putrescin significantly reduced the changes in soluble solids. The treatment of polyamide fruits slowly reduces the amount of total soluble solids that can be delayed in the production of ethylene and the ripening of fruit. It seems that the effect of polyamide treatments on their ability to maintain acidic conditions and the total acid content of the fruit extract, is related to their ability to compete with ethylene and delay in the ripening process. The amount of phenol over time has been increased. Phenol content of fruits and vegetables can be reduced or increased, which depends on storage conditions. With increasing maintenance period, the activity of PEL enzymes increases in different stages of harvesting, so that it has the highest amount at the time of commercial maturation. Based on the results of this study, it was observed that co-application of Putrescin coated treatments with aloe vera gel maintains biochemical parameters in terms of storage of peach fruit. Generally, the combination of 6 μM Putrescin and 30% Aloe Vera combination therapy had the best effect among other treatments in maintaining the traits in tomato fruit.
Saman Abdanan; Mehran Nouri; Maryam Soltani Kazemi; Somaye Amraei
Abstract
Introduction: Nutritional quality of food during storage has become increasingly an important problem. The loss of some nutrients such as ascorbic acid (vitamin C) might be a critical factor for the shelf life of some products as citrus juice concentrates, since vitamin C content of citrus juices undergoes ...
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Introduction: Nutritional quality of food during storage has become increasingly an important problem. The loss of some nutrients such as ascorbic acid (vitamin C) might be a critical factor for the shelf life of some products as citrus juice concentrates, since vitamin C content of citrus juices undergoes destruction during storage (Plaza et al., 2011a). Ascorbic acid is an important component of our nutrition and used as additive in many foods because of its antioxidant capacity. Thus, it increases quality and technological properties of food as well as nutritional value (Larisch et al., 1998). However, ascorbic acid is an unstable compound and even under minor desirable conditions it decomposes easily. Degradation of ascorbic acid proceeds both aerobic and anaerobic pathways and depends upon many factors such as oxygen, heat, light, storage temperature and storage time. Oxidation of ascorbic acid occurs mainly during the processing of citrus juices, whereas, anaerobic degradation of ascorbic acid mainly appears during storage which is especially observed in thermally preserved citrus juices (Lee & Coates, 1999). It was reported that several decomposition reactive products occur via the degradation of vitamin C and these compounds may combine with amino acids, thus result in formation of brown pigments (Wibowo et al., 2015). In recent years, several nondestructive methods such as computer vision, spectroscopy, ultrasonic have been developed to objectively evaluate different agricultural materials (Abdanan Mehdizadeh et al., 2014; Wang and Paliwal, 2007). However, due to the physical properties of fruit, machine vision has not been discussed much in the literature (Fernanzed-Vazquez et al., 2011). One disadvantage of using spectroscopic methods is that these methods require expensive equipment and also carrying these instruments are difficult. On the contrary, the combining of a digital camera and its image processing software that replaces the traditional measuring instruments have been widely used to provide a cheaper and versatile form to measure some internal quality of many foods. Therefore, the goal of this research is to determine the best features of surface texture (entropy, homogeneity, contrast, correlation and prominence) in order to predict quality factors (pH, acidity, soluble solids and ascorbic acid) of citrus juice.
Materials and methods: Orange, sour lemon, sour orange and tangerine fruit were obtained from one of local marker in Ahvaz, Iran. All samples were washed and the juice was extracted using a Pars-Khazar rotary extractor. The citrus juice, (sour orange, orange, lemon and tangerine) immediately after pasteurization process, were kept at a temperature of refrigerators (4º C) for 60 days in darkness. After taking images of the citrus juice, pH, acidity, ascorbic acid and soluble solids were measured on days 0, 20, 40 and 60.
Physicochemical analysis:
The pH of samples was determined with a pH meter (Methrohm, 827 pH lab, Switzerland). The soluble solids content of concentrates was determined as o Bx using a refractometer (Atago Co, Ltd. Carnation, WA). Total titrable acidity was assessed by titration with sodium hydroxide (0.1 N) and expressed as % citric acid (Kimball, 1999). Ascorbic acid was determined using 2,6-dichlorophenolindophenol by visual titration (Kabasakalis, 2000).
Imaging and color analysis:
Samples were placed under the camera (Canon PowerShot SX60 HS, Japan) of a computer vision system at the distance of 300 mm inside a black box with the size of 100 ×100 ×100 cm3. The samples were illuminated using four fluorescent lamps at the angle of 45o in relation with the sample.
After taking images, color images were transformed to L*a*b* color space. The L* parameter (luminosity) is an attribute by which a surface emits more or less light and can take values between 0 (absolute black) to 100 (absolute white). The parameters a* and b* represent the chromaticity, where a* defines the red-green component (red for positive values and green for negative values) and the b* parameter defines the yellow-blue component (yellow for positive values and blue for negative values) (Quevedo et al., 2009a). Following color transformation, the well-known textural parameter called the Gray-Level Co-Occurrence Matrix (GLCM function) was applied to the images and six features through Eq. 1-6 were extracted (Table 1).
Results and discussion: Color changes during storage in three color channels L*,a*,b* showed that the variation of channel L* could illustrate deterioration of citrus juice better than other channels. In the Figure 1, a gallery of four selected images (taken at different times in the experiment) corresponding to one sour orange sample and their corresponding surface intensity (based on L* value) are showed.
The results of statistical analysis depicted that acidity and ascorbic acid, in four citrus juices, significantly (P
Hamed Hosseini; Mohammad Ghorbani; Alireza Sadeghi Mahoonak; Yahya Maghsoudlou
Abstract
Oxidative stability of walnut (Juglansregia L.) was evaluated over a period of 1 year storage in various conditions. The whole walnuts, walnut kernels, walnut chopped kernels, walnut kernels packaged in polyethylene (PET) under vacuum and poly propylene (PP) contain of CO2 were kept in a normal condition ...
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Oxidative stability of walnut (Juglansregia L.) was evaluated over a period of 1 year storage in various conditions. The whole walnuts, walnut kernels, walnut chopped kernels, walnut kernels packaged in polyethylene (PET) under vacuum and poly propylene (PP) contain of CO2 were kept in a normal condition (temperature, 19-30˚С and relative humidity (RH), 35-45%). The whole walnuts and walnut kernels were also kept in refrigerator (4˚С, RH 75%). Some quality parameters for the oil extracted from walnut kernels were measured throughout the storage. Peroxide value of whole walnuts, walnut kernels and walnut chopped kernels pass over 2 meq O2/kg after 12, 10 and 8 months storage, respectively. Peroxide value of the packaged nuts and the nuts stored at cold storage were increased only 1 meq O2/kg over a period of 1 year storage. According to the statistically analysis results, the effect of storage condition and storage time on oxidative stability of walnuts were significant (p walnuts shell > contact surface of walnut kernels with environment were defined to maintain the quality of walnut kernels during long term storage.
