Food Technology
Hosein Ghavami; Azin Nasrollah zadeh
Abstract
Introduction
All the different species of hazelnut trees produce edible nuts. Hazelnuts are one of the most nutritious nuts, with a protein content of about 12%. They are also a good source of energy, with a fat content of about 60%, and an excellent source of carbohydrates, half of which are ...
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Introduction
All the different species of hazelnut trees produce edible nuts. Hazelnuts are one of the most nutritious nuts, with a protein content of about 12%. They are also a good source of energy, with a fat content of about 60%, and an excellent source of carbohydrates, half of which are dietary fiber. Hazelnuts also contain minerals (Ca, Mg, P, K), vitamins (E and B), and antioxidants. Hazelnut kernels may be eaten raw or roasted. Roasting alters and significantly enhances the color, texture, and appearance of nuts. These changes increase the overall palatability of the nuts and are mainly related to non-enzymatic browning. Non-enzymatic browning, however, causes a decrease in nutritional value due to decrease in protein digestibility and loss of essential amino acids. The most widely used nut roasting method is the convective heat transfer process, which is performed in a hot air oven working either in continuous mode or in batch systems. Therefore, modifying this process for improving product quality is very important. Color is among the most important quality attributes of dehydrated foods for consumers. Empirically, color is also an effective quality indicator because the brown pigments increase as the browning and caramelization reactions progress. Therefore, this study aimed to investigate the effect of high roasting temperature and storage time on color changes and oxidation of hazelnut paste oil.
Materials and Methods
After getting hazelnut kernels, the Roasting process was performed with hot air at 130 and 170 ℃ for 20 minutes. Hazelnut paste is produced as practiced in the industry. Quality analysis was roasted hazelnut paste color changes and fat oxidation. L *, a *, b * color index, (∆E), acidity, and peroxide value were measured in three intervals (0, 10, 30 days’). All experiments were performed in three replications. Average Data was compared using one-way ANOVA and done by SPSS version 21.
Results and Discussion
The main purpose of roasting is to improve the flavor, the color, and the crispy and crunchy texture of the product. The roasting process is very important to determine the characteristic roasted flavor and color of the product: in particular, temperature modulation is an important independent variable significantly affecting the quality features of hazelnut. In this study, ANOVA analysis results showed a significant difference between the treatments. Both roasting temperature and storage time affect the acidity and peroxide value. The increased temperature and storage increased the acidity and peroxide index, which indicated fat oxidation at higher temperatures. For ten days, the sample's peroxide value increased. After that, these parameters decreased because the first autoxidation products changing to the second product. Due to the release of free fatty acids after the basic hydrolysis of triglycerides, the acidity of the samples increased. The Browning color of roasted products was desirable. Discoloration during the roasting process of hazelnut kernels is mainly related to non-enzymatic browning. The brown pigments increase with the development of browning reactions. Results showed that the color index includes the L*, a*, b*, and ∆E values of the samples only affected by roasting temperature. With increasing the temperature, the L* value decreased but other values increased. Color indicators significantly changed and are not desirable for the consumers. The rate of color changes increased, including browning, indicating a non-enzymatic browning reaction in the samples during roasting.
Conclusion
According to the results, hazelnuts roasted at 130℃ introduced as the best treatment. It is recommended that the storage time does not exceed ten days.
Food Technology
Maryam Alsadat Nazemi; Sara Ansari
Abstract
Introduction: Roasting is one of the most important thermal processing to improve the physicochemical and organoleptic properties of nuts. Wild almond, especially roasted wild almond is very sensitive to oxidation due to its high content of unsaturated fatty acids. Lipid oxidation can be inhibited by ...
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Introduction: Roasting is one of the most important thermal processing to improve the physicochemical and organoleptic properties of nuts. Wild almond, especially roasted wild almond is very sensitive to oxidation due to its high content of unsaturated fatty acids. Lipid oxidation can be inhibited by using a suitable packaging material and modifying the atmosphere of the packaging. In this research, the effects of roasting degree (light roasting at 50°C/60 min, medium roasting at 100°C/45 min and dark roasting at 200°C/ 30 min), as well as the presence/ absence of nitrogen gas in two types of pouches including polyethylene (PE) and oriented polypropylene/ cast polypropylene (OPP/CPP) were investigated. The effects of above mentioned treatments were examined using Completely Randomized Design on the moisture, total fat, firmness, peroxide value and conjugated trienes, fatty acid profile and sensory properties during two months storage at 37°C. Materials and Methods: The wild almonds used in this research were collected randomly from the Dasht-e-Arjan region in Fars province (Iran). The debittering process of almonds was done by soaking in 4- 6 % (w/v) of NaCl solution for 12 hours at three consecutive days. A certain amount of debittered wild almonds with a uniform size were roasted at 50°C for 60 minutes (light- roasting), 100°C for 45 minutes (medium- roasting) and 200°C for 30 minutes (dark- roasting) in a laboratory toaster (SSN-2004x, Iran). After cooling at room temperature, samples of 100 g were packed using gas flushing packing machine (90SM4, Shadmehr Co., Iran) in three different conditions: a) air atmosphere (in transparent PE pouches, 70- 75 mm thickness), b) modified atmosphere flushed with N2 gas (in transparent PE pouches, 70- 75 mm thickness), c) modified atmosphere flushed with N2 gas (in two-layer transparent OPP-CPP pouches, 25 and 50 mm thickness of the first and second layer). The samples were stored for two months at 37°C and 7-8% R.H. At definite time intervals, the samples were analyzed for the moisture content by oven drying, total oil content by the soxhlet method, protein content by the Kjeldahl method, and fiber content through chemical gravimetric method. Extraction of oil from the nut samples was carried out using hexane, as described by Kornsteiner et al. (2009). Peroxide value (PV) was determined by the iodometric assay according to IUPAC standard method 2.501. Conjugated trienes were calculated according to IUPAC Official Method 2.205 based on measuring absorbance of a solution containing 0.01-0.03 g of oil in 25 ml of isooctane. The fatty acid composition of wild almond oils was determined by gas chromatography equipped with flame ionization detection. Hardness of the wild almond was evaluated using a Texture Analyzer (CT3-Brookfield, USA). Sensory evaluation of samples was carried out by 30 trained panelists using a five point hedonic scale. Statistical analysis of completely randomized design with three replications and means comparison in 95% confidence level was employed using the SPSS-19 software. Results and Discussion: Analysis of variance indicated that the independent effects of roasting conditions, packaging and storage time and the interaction of roasting conditions and storage time on the mentioned parameters were significant (p<0.01). With roasting at higher temperatures, the moisture content and hardness decreased significantly while the oil, protein and fiber content of wild almond kernels and the peroxide value (PV) and conjugated trienes (CT) of their oils increased significantly. However, the increase in protein and CT for medium and low roasting conditions and the increase in fiber for medium and high roasting conditions were not significant (p>0.05). Moreover, increasing the roasting temperature of wild almond led to a significant increase of palmitic acid and a significant decrease of stearic acid whereas other fatty acids did not change significantly. There was a remarkable increase and then a rapid decrease in the fiber, fat and protein content of all roasted samples during the first and second months of storage, respectively. Whereas the PV and CT of oils increased and the moisture content and hardness decreased significantly during the two- months storage. For each roasting temperature, wild almonds packaged in pouches under N2 had lower PV and CT of oils and the OPP/CPP pouches under N2 had better performance in this regard and retaining moisture, fat, protein, fiber content and texture. At the end of storage with PV of 24.6 (meqO2/kg oil) and K268 of 1.92 the dark-roasted almond sample packaged with PE/air atmosphere was the least stable, and the light-roasted sample packaged with OPP/CPP under N2 with PV of 5.3 (meqO2/kg oil) and K268 of 1.57 was the most stable form against oxidation. According to the results of sensory analysis, the highest overall acceptability score was attributed to the samples roasted at 100°C for 45 minutes.
Food Chemistry
Maryam Ravaghi; Azadeh Khodabakhshian
Abstract
Introduction: Peanut is a high-protein, nutrient-rich legume that is popular all around the world. Peanut butter is a kind of food paste made from ground roasted peanuts. It is found to be one of the most susceptible food products to oxidation due to its high content of PUFAs. Peroxide value is the only ...
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Introduction: Peanut is a high-protein, nutrient-rich legume that is popular all around the world. Peanut butter is a kind of food paste made from ground roasted peanuts. It is found to be one of the most susceptible food products to oxidation due to its high content of PUFAs. Peroxide value is the only mentioned parameter for oxidation of peanut butter according to ISIRI 5690. Although oxidation pathways are mostly known, there are a lot of ambiguities about oxidation in real situations after production and during storage so there is a lack of studies in this field. Materials and Methods: The present study investigated the effect of packaging and storage conditions on the oxidation of peanut butter in polypropylene single serving cup (PP) and polyethylene terepthalate (PET) jar due to widespread applications of these plastic materials in food industries. Peanut butter stabilized with mono and di-glycerides was filled in PP single serving cup (size: 30 g), and PET jar (250 g), then heat sealing was applied. Determination of chemical composition (moisture, fat, protein, sugar, ash and salt), fatty acids profile and microbial quality (total count, coliform, E. coli, coagulase positive Staphylococci, Salmonella, mold and yeast) was performed for produced samples. The study was conducted for 160 days at storage temperature of 4, 25 and 40°C on peanut butter and storage stability at specific time intervals (0, 30, 60, 90, 120, 160 days) was evaluated for changes in p-Anisidine value, peroxide value, acidity and sensory analysis. All analyses were carried out in triplicate and significant differences were determined using Duncan's multiple range test (p<0.05). Results and Discussion: Peanut butter had a fat content of 54.55±0.85% which contained 80.92% unsaturated fatty acids (57.57% MUFAs and 23.35% PUFAs). PUFAs are susceptible to oxidation and are easily incorporated into the chain reaction mechanisms of lipid degradation. There was no sign of microbial contamination in produced peanut butter. Time and temperature had a significant interaction on peroxide value, p-Anisisdine value, acidity and sensory analyses in both of packaging materials. Different trends were observed in peroxide value data of peanut butter packaged in different plastics. Peroxide values were higher in PP compared with PET due to higher oxygen permeability through PP. PP cups stored at 40 ̊C had the highest amounts of peroxide value (52.55± 2.27 mEq/kg) and p-Anisisdine value (4.10± 0.22). Oxidation of peanut butter in PET jar occurred at lower rate. One notable point is that peroxide value at 40°C (4.61±1.04 mEq/kg) was less than 4°C (15.51±1.09 mEq/kg) and 25°C (14.19±0.78 mEq/kg) after 160 days. These values never reached the maximum standard limit (12 mEq/kg) at 40°C. Temperature of 4°C might not provide enough energy to convert hydroperoxides into other oxidation products so peroxides accumulated in peanut butter. Though significant differences were observed among data of acidity in both of packaging materials but differences were not large enough to be of value in a practical sense. As it was expected peanut butter did not provide its initial fresh taste especially at higher temperature but no sign of off-flavor and rancidity was detected by panelists. According to the obtained results,using polypropylene single serving cup for peanut butter led to decrease its shelf life due to its higher permeability to oxygen. In this situation samples should be kept under cold storage. To overcome this problem coated PP or other plastic materials with higher oxygen barrier properties are suggested. Peroxide value was the only indication of oxidation which was mentioned in ISIRI 5690, while it seems that determination of such a parameter in this product is not a proper index of quality.
Olga Azimi; Mohebbat Mohebbi; Reza Farhoosh; Mahdi Saadatmand-Tarzjan
Abstract
Discerning the expiration status (non-rejected and rejected) of edible vegetable oils is very significant because of the hazardous primary and secondary oxidation products. Therefore, it is of outmost importance to monitor the quality and safety of these oils. Based on previous literature, reports and ...
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Discerning the expiration status (non-rejected and rejected) of edible vegetable oils is very significant because of the hazardous primary and secondary oxidation products. Therefore, it is of outmost importance to monitor the quality and safety of these oils. Based on previous literature, reports and experimental observation, the oil color changes during oxidation. Thus, the present study investigates the use of image processing and linear discriminant analysis (LDA) for the classification of non-rejected and rejected edible vegetable oils during oxidation process at 85°C, with respect to the induced period in both primary and secondary oxidation of four oil type (Olive, Sunflower, Palm and Soybean). The purpose of this study was to find less costly and quicker methods with environmental protection, by using the color spaces (RGB, HSI, L*a*b* with Grayscale) instead of chemical analyses to determine the expiration status of edible vegetable oils. Results of this study indicated that the best classification for expiration status of known oils according to induced period of peroxide value in each color space, was achieved with LDA model were for palm with 100% (HSI and Grayscale), olive with 84.61% (L*a*b* and RGB), soybean with 95% (Grayscale) and sunflower with 100% (RGB and HSI), also in induced period of carbonyl value test, the best classification performance was achieved in palm with 100% (L*a*b*), olive with 100% (L*a*b*), soybean with 89.47% and sunflower with 95% (HSI).
Somayeh Rastegar; Azam Shojaee; Behjat Tajeddin
Abstract
Introduction: Persian walnut (Juglans regia) from Juglandaceae family is one of the most important fruits in the world that has an important role in human health. It contains a notable list of plant nutrients that has been found to have disease preventing and health promoting properties. Walnut is a ...
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Introduction: Persian walnut (Juglans regia) from Juglandaceae family is one of the most important fruits in the world that has an important role in human health. It contains a notable list of plant nutrients that has been found to have disease preventing and health promoting properties. Walnut is a source of bioactive compounds such as phenolic and flavonoid complexes where they act as antioxidants and free radical scavengers. It also contains pleasant flavor and high concentration of minerals and fatty acids. Extending shelf-life of this perishable fruit has been accomplished due to its high oil level and oxidation of oil (Tajeddin, 2004). Rate of loss in walnut kernel quality and quantity between harvest and consumption affects its productivity. Control of temperature is the most effective tool for extending the shelf life of fresh horticultural products. However, to reduce high losses and keeping product’s quality, packaging method is very important as well as low temperature. Therefore, in this study, the effect of temperature (4 and 25 oC) and packaging methods (vacuum and air packaging) on the changes of walnut kernel compounds was evaluated to improve quality of its storability during six month cold storage.
Materials and methods: Walnut harvested from a commercial garden at the mountain regional of Raber, Kerman province. All chemical materials for different tests obtained from Merck Company, Germany. Immediately after walnuts harvesting, they were dehulled and dried in expose of sun shade with the circulation of natural air. The walnuts were then transferred to the laboratory and their wooden shells were removed. Subsequently, about 25 g of walnut kernel was packaged in the polyethylene films with 87μm (0.087 mm) thickness, under a vacuum machine and stored at 4°C and 25°C to be later assessed for further analyses intended for six months. Phenol, flavonoid, carbohydrate, protein, water percent, color parameters (C, h, WI), organoleptic characteristics, and peroxide value of kernels were measured every month during storage time. The control samples of packaged walnuts under environmental conditions were also stored. The current study carried out as a factorial assay on the basis of a completely randomized design with three replications at Hormozgan University. Data were subjected to ANOVA using SAS software version 9.4. Verification of significant differences was done using Duncan's Test at 1% probability level.
Results and discussion: Results showed that carbohydrate and proteins decreased during storage time. Both of vacuum package and low temperature contorted the reduction of different characteristics of kernel such as bioactive compounds during storage significantly. Sensory properties were also reduced during storage, especially at the end of period, in all conditions except for treatment at 4°C and vacuum packing. Control samples (temperature 25°C and air-containing packags) during the experiment showed a lower quality for all factors. Samples that stored in low temperature and vacuum package had better brightness (higher chroma, Hugh, lightness (L) and white index values (Wi)) than other treatments. The treatments had a significant role in the preventing of increasing peroxide value. The peroxide value in treated samples was increased from 0.023 to 0.68 meq/g, while in vacuum packages it was changed from 0.023 to 0.37 meq/g. Increasing of peroxide value was observed from 0.023 to 0.68 and from 0.023 to 0.25 meq/g in room temperature and cold temperature, respectively. After six months, the average peroxide value in all samples was less than one milliequivalent per oil kilogram. Decreasing of phenolic compounds (30%) and flavonoids (35%) and increasing the peroxide index simultaneously led to the reduction of the appearance and organoleptic properties of the control samples. Generally, vacuum package and low temperature condition that using in this study showed the best effect on the nutritional compounds quality of walnut kernel such as bioactive components during six months storage. Shelf life enhancement of walnut by vacuum packaging in the different polymers has been already reported by Tajeddin, 2004.
Adeleh Mohammadi; Saeedeh Arabshahi- Delouee
Abstract
Introduction:Frankincense is a natural oleo-gum-resin which is obtained through slits made in the trunks of trees of the genus Boswellia (Family Burseraceae). The genus Boswellia is approximately represented by 43 different trees and shrubs distributed mostly in the India, Arabian peninsula, and east ...
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Introduction:Frankincense is a natural oleo-gum-resin which is obtained through slits made in the trunks of trees of the genus Boswellia (Family Burseraceae). The genus Boswellia is approximately represented by 43 different trees and shrubs distributed mostly in the India, Arabian peninsula, and east africa (mothana et al.2011). Trees from the genus Boswellia (Burseraceae) are traditionally used as a medicine, a fumigant, in various cosmetic formulations and in aromatherapy in several countries around the world.Frankincense therapeutic effect significantly depends on the amount of oleoresin. These effects include anti-inflammatory, hepatoprotective, anticancerous, anti-HIV, anti-microbial, antifungal, anti-ulcerous, gastroprotective, hypoglycemic andantihyperlipidemic properties (Aman et al. 2009; Al-Harrasi and Al-Saidi, 2008; Khadem et al. 2009 and Shah et al.2009).Lipids are susceptible to oxidation on storage and frying processes. Characteristic changes associated with oxidative deterioration include development of unpleasant tastes and odors as well as changes in color, specific gravity, viscosity and solubility.Lipid peroxidation is one of the major agents of deterioration for vegetable oils, fats and other food systems (Iqbal and Bhanger, 2007). During oxidation hydroperoxides are formed which again break down to form products like alcohols, aldehydes, ketones and hydrocarbons, which possesses offensive off flavors (Grace Roy et al.2010).In order to inhibit oxidation, synthetic antioxidants, such as BHA (Butylated hydroxyanisole), BHT (Butylated hydroxyanisole) and TBHQ Ter-butyl hydroquinone have been added to foods but there is concern about the use of these compounds due to their reported adverse effects on health. This has led to an increasing trend in the search and replace of these synthetic antioxidants with natural ones such as phenolic compounds (Mariod et al. 2006).Antioxidants affect the process of lipid oxidation at different stages due to differences in their mode of action. Because of the complexity of the oxidation process itself,the diversity of the substrates and the active species involved, the application of different test methods is necessary in the evaluation of antioxidants. The aim ofthisstudy was to evaluatethe antioxidantproperties of various solvent extractsand essential oil offrankincense(Boswellia serrata)and evaluation ofitsantioxidant activityinsoybeanoil.Materials and methods: In this study, the dried powder of B.serrata (25g) was extracted overnight in 250 ml each of methanol, ethanol and acetone respectively, in a mechanical shakerat room temperature and each extract was filtered with Whatman No. 1 filter paper. The filtrates obtained from methanol, ethanol and acetone extractions were evaporated at 40 °C in a rotary evaporator. The content of phenolic compounds was measured by Folin–Ciocalteu, Briefly 20 µl of extract solution were mixed with 1.16 ml distilled water and 100 µl of Folin–Ciocalteu reagent, followed by addition of 300 µl of Na2CO3 solution (20%) after 8 minutes. Subsequently, the mixture was incubated at oven at 40 °C for 30 minutes and its absorbance was measured at 760 nm.The ability of extracts to scavenge DPPH radicals was determined according to the method of Blois (1958). Briefly, 1 ml of a 0.1 mM methanolic solution of DPPH was mixed with 3 ml of extract solution in methanol (containing 100–1000 μg/ml). The mixture was then vortexed and left for 30 min at room temperature in the dark. The absorbance was measured at 517 nm. The percentageof the DPPH radical scavenging was calculated using the equation given below:% inhibition of DPPH radical= ( Abr - Aar ) / Aar×100where Abr is the absorbance before reaction and Aar is theabsorbance after reaction has taken place. The molecule 1, 1-diphenyl-2-picrylhydrazyl (a,a-diphenyl-bpicrylhydrazyl DPPH) is characterized as a stable free radical by virtue of the delocalisation of the spare electron over the molecule as a whole, so that the molecule does not dimerize, as would be the case with most other free radicals (Nur Alam et al., 2013).Next, oxidative stabilityand antioxidant activity of methanol extract concentrations (200, 500, 800, 1000 ppm) with the synthetic antioxidant TBHQ (100 ppm) were evaluated in soybean oil without antioxidants (63 ˚C, 12 days).Results and discussion: The extract significantly (p0.05) suppressed the formation of peroxides and thiobarbituric acid-reactive substances (TBARS) during accelerated oxidation, even at a level of 200 ppm. Based on the obtained results, the methanolic extract at 1000 ppm had the highest antioxidant activity among other extracts and inhibits the peroxide value and the index of thiobarbituric acid, but it coulden't compete with the synthetic antioxidant TBHQ. Results showed that, Boswellia Serrata was found as a potential source of natural antioxidants due to its marked antioxidant activity.
