Effect of superheated-steam roasting on physicochemical properties of peanut (<Emphasis Type="Italic">Arachis hypogea</Emphasis>) oil

Peanut (Arachis hypogaea) is an important source of protein and lipid globally. The effect of superheated-steam roasting on quality of peanut oil was evaluated based on physicochemical quality parameters. Three roasting temperatures (150, 200, and 250 °C) were used for different periods of roasting time and the obtained results were compared with those of conventional roasting. At 250 °C, superheated-steam roasted peanuts yielded more oil (26.84%) than conventionally roasted peanuts (24.85%). Compared with conventional roasting, superheated-steam roasting resulted in lower oil color, peroxide, p-anisidine, free fatty acid, conjugated diene and triene, and acid values and higher viscosity and iodine values in the roasted peanut oil. These values were significantly different from each other (p < 0.05). The fatty acids in roasted peanut oils were affected by roasting temperature and time for both the roasting modes. The superheated steam technique can be used to roast peanuts while maintaining their favorable characteristics.     

Tocopherols in cocoa butter obtained from cocoa bean roasted in different forms and under various process parameters

Obtaining good quality chocolate strongly depends on raw material, i.e. cocoa beans. The processing of cocoa beans consists of some important steps, including fermentation, drying fermented beans and roasting. Traditionally roasting is performed on whole beans but currently, roasting crushed cocoa beans or cocoa liquor becomes more and more popular. Many biologically active compounds may be found in the cocoa beans, including tocopherols. This work investigates the influence of the constant or variable roasting process parameters (temperature, velocity and relative humidity of roasting air) on the tocopherol concentration in cocoa butter (CB) extracted from cocoa beans originating from Togo and roasted in two different forms, namely as whole and crushed beans. Whole cocoa beans were roasted to a 2% moisture content and crushed cocoa beans were firstly partially dried which further enables easier dehusking, then ground, dehusked and roasted until their humidity decreased to around 2%. Roasting resulted in lowering the content of individual tocopherols in analyzed material. The degree of degradation of tocopherols in CBs was different, depending on the form of roasted beans from which these CBs were extracted. Higher concentrations were determined in CBs extracted from beans roasted in the form of crushed samples comparing to CBs obtained from beans roasted as a whole. The study investigates different roasting parameters of crushed beans, none of which drastically lowered the concentration of tocopherols in extracted CBs. Their concentration in CBs extracted from whole beans was, on the other hand, influenced by roasting air parameters. In case of whole beans roasted under constant parameters, application of 150 °C proved to be more favorable than roasting at 135 °C, as well as application of “dry” air and 1 m/s roasting air velocity. Discussing the variable roasting process parameters, in case of applied roasting temperature it is more favorable to change it from 150 °C to 135 °C, than the other way round. Changing the relative humidity of roasting air from 5 to 0.3%, lower degradation of tocopherols in CB occurs when the process is conducted at 150 °C. It may be further concluded that a direct dependence between the velocity of roasting air varied during the process and the concentration of tocopherols in extracted CB may not be indicated. In conclusion, it is stated that the temperature of the air applied during the roasting process has the decisive influence on the tocopherol content in CBs extracted from cocoa beans subjected to the process.     

Profiles of volatile compounds and sensory characteristics of Robusta coffee beans roasted by hot air and superheated steam

Although superheated steam (SHS) roasting has proved to be capable of improving selected quality of roasted Robusta coffee beans, impact of SHS roasting on aroma characteristics of the beans is not well understood. This study therefore aimed to investigate the effect of SHS roasting on aroma profiles and sensory characteristics of Robusta beans undergone SHS roasting at 190–250 °C; results were compared with those of beans roasted by hot air (HA). Sensory characteristics of selected samples were also compared with HA-roasted Arabica beans. Forty five aroma compounds were identified; most were fully developed in beans roasted at 230 °C and tended to degrade in beans roasted at 250 °C. SHS roasting led to more extensive formation of aroma compounds contributing to caramel note, while helped reduce formation of major contributors to spicy, roasty and burnt notes. SHS-roasted Robusta beans exhibited more resemblance to Arabica beans than their HA-roasted counterpart.     

Influences of Superheated Steam Roasting and Water Activity Control as Oxidation Mitigation Methods on Physicochemical Properties,Lipid Oxidation,and Free Fatty Acids Compositions of Roasted Rice

The feasibility of using superheated steam roasting and wetting to control the water activity in an optimal range to mitigate oxidation of roasted rice was evaluated. Changes in the bed temperature as well as rice kernel moisture content, water activity, and color were monitored during fluidized bed roasting with superheated steam and hot air at 170, 190, and 210 °C. Air‐roasted rice was rewetted to raise its water activity to 0.30 to 0.35. All the samples were analyzed for the total oil content, peroxide value (PV), thiobarbituric acid (TBA) value, and free fatty acids (FFA) content and compositions. Higher roasting temperatures, especially at 210 °C, led to a significant increase (P ≤ 0.05) in the total oil content of the roasted rice. Wetting led to a significant (P ≤ 0.05) decrease in the TBA value of the air‐roasted rice, although the total FFA content significantly (P ≤ 0.05) increased. Rice roasted in superheated steam at 210 °C exhibited significantly (P ≤ 0.05) lower PV and TBA value; their total FFA content also tended to decrease, which is desirable for a longer shelf life.     

Influence of roasting conditions on fatty acid composition and oxidative changes of cocoa butter extracted from cocoa bean of Forastero variety cultivated in Togo

Cocoa butter is responsible for physico-chemical, rheological and sensory properties of chocolates. Forastero cocoa beans are rich in cocoa butter. Roasting of cocoa beans is an essential step of their processing, giving rise to many desirable transformations. On the other hand, it causes changes in certain valuable ingredients including also cocoa butter. This article studies the influence of roasting conditions, i.e. temperature, humidity and flow velocity of roasting air, on the fatty acid composition, peroxide value and content of conjugated dienes and trienes in cocoa butter extracted from cocoa beans. Generally, in most cases roasting did not increase the peroxide value. In the constant conditions due to obtained results of PV, CD and CT values it is recommended to roast cocoa beans at the temperature of 150 °C, 1 m/s air velocity and 5% relative humidity. In the variable conditions lower values of PV, CD and CT were achieved when cocoa beans were roasted in variants with changing temperature from 150 °C to 135 °C or with changing air velocity from 1 to 0.5 m/s. Generally, the roasting process substantially did not change the content of each fatty acid, regardless of the applied conditions.     

Effects of seed roasting temperature and time on the quality characteristics of sesame (Sesamum indicum) oil

The quality characteristics and composition of sesame oils prepared at different roasting temperatures (160–250°C) from sesame seeds using a domestic electric oven were evaluated as compared to an unroasted oil sample: only minor increases (P<0·05) in characteristics, such as peroxide value, carbonyl value, anisidine value and thiobarbituric acid reactive substances, of sesame oils occurred in relation to increasing roasting temperature and time between 160 and 200°C, but colour units of oils increased markedly over a 220°C roasting temperature. Significant decreases (P<0·05) were observed in the amounts of triacylglycerols and phospholipids in the oils prepared using a 250°C roasting temperature. The amounts of γ-tocopherol and sesamin still remained over 80 and 90%, respectively, of the original levels after roasting at 250°C. In the oil prepared using a 250°C roasting temperature, sesamol was detected at 3370 mg per kg oil, but sesamolin was almost depleted after 25 min of roasting. Burning and bitter tastes were found in the oils prepared at roasting temperatures over 220°C. The results suggested that a high-quality product would be obtained by roasting for 25 min at 160 or 180°C, 15 min at 200°C and 5 min at 220°C when compared with the other samples. © 1997 SCI.     

Antioxidant Properties of Cocoa Beans (Theobroma cacao L.): Influence of Cultivar and Roasting Conditions

Effects of various roasting conditions on antioxidant properties of five Theobroma cacao L. varieties were investigated. The cocoa beans were roasted at four different temperatures (110–150°C) and three different air humidities (0.3–5.0%). The raw cocoa beans were characterized by high antioxidant activities. The antioxidant properties of the roasted cocoa beans varied markedly among the analyzed cultivars and geographical regions and were affected by roasting conditions. Generally, cocoa beans of the cv. Forastero from Brazil exhibited higher total phenolic content, free radical scavenging activity, and metal chelating ability than samples of the other analyzed cocoa varieties. Roasting at 110°C caused negligible changes in total phenolics content and antioxidant activity of cocoa beans, while almost all samples tended to have lower antioxidant potential when roasting temperature increased. The air humidity used in roasting did not affect the total phenolics content and antioxidant activity for lowest roasting temperature (110°C). Moreover, the obtained results revealed that thermal processing at the higher temperatures and elevated air humidity resulted in the higher antioxidant capacities. It was also found that the ferrous ion chelating activity of cocoa beans increased with the roasting temperature (in the range from 110 to 150°C), with the exception of cv. Trinitario from Papua New Guinea. The data showed that roasting at lower temperatures with humid air are more favorable in terms of preserving the bioactivity of roasted cocoa beans.     

Effect of roasting conditions on the antioxidant compounds of quinoa seeds

The effect of different roasting conditions on the antioxidant properties and the phenolic content of quinoa seeds was studied. Advanced and final products of the Maillard reaction were also quantified in order to evaluate the contribution to DPPH radical scavenging capacity and reducing power of samples. In general, response surface analysis showed significant increases in the phenolic content, the antioxidant activity and the level of Maillard reaction products (MRPs), mainly as processing temperature increased, while roasting time had a minor impact on these response variables. The highest antioxidant activity was achieved in extracts of quinoa seeds roasted at 190 °C for 30 min. Principal component analysis applied to the data suggested that MRPs had a greater contribution to antioxidant properties than phenolic compounds in the processed samples. These results demonstrated that roasted quinoa seeds/flour may be considered as a nontraditional ingredient with enhanced antioxidant capacity for the production of functional foods.     

Influence of quinoa roasting on sensory and physicochemical properties of allergen‐free,gluten‐free cakes

The objectives of this study were to determine pasting properties of non‐roasted (NR) and roasted quinoa (RQ) and to investigate the effect of RQ on consumer acceptance and physicochemical properties of an allergen‐free, gluten‐free cake formulation. Quinoa seeds were roasted at 177 °C for 15 (R15), 30 (R30) and 45 min (R45), and flours were analysed for pasting properties. Five cakes including a commercial chocolate cake (CCC) and cakes made with NR and RQ flours were evaluated for preference by fifty panelists. Quality parameters included colour, water activity, moisture content, firmness, weight and height. Peak and final viscosity increased with roasting time. The NR cake had the highest sensory scores for appearance, colour and texture. On flavour and overall acceptability, CCC was the highest. Regarding quality data, CCC, NR and R15 cakes had similar L* values, while CCC had the lowest a*, b*, a_w, moisture content and firmness values.     

Influence of seed roasting process on the changes in composition and quality of sesame (Sesame indicum) oil

The composition and quality changes of sesame oils prepared at different roasting temperatures (180–260°C) from sesame seed were evaluated and compared with an unroasted oil sample. There were no apparent differences in characteristics, such as acid value, iodine value, saponification value and refractive index, of sesame oils prepared at a roasting temperature between 180 and 220°C. The colour units and total polar content of oils increased in relation to an increase in roasting temperature. The phospholipid content was reduced from 690 mg kg^?1 in unroasted oil to 0 mg kg^?1 in the oil prepared using a 260°C roasting temperature. The fatty acid content of the oil was reduced markedly, especially in oleic and linoleic acids, when the roasting temperature was over 220°C. The amounts of chlorophyll and sesamolin decreased with increasing roasting temperature. However, the highest level of sesamol and γ-tocopherol was found in oils prepared with a 200–220°C roasting temperature. The sesame oil prepared at a 200°C roasting temperature had the best flavour score when compared with the other samples.     

Effect of hot water treatment of in-shell pecans on physicochemical properties and consumer acceptability of roasted pecan kernels

The effect of hot water pre-treatment of in-shell pecans on physicochemical properties, consumer acceptance and purchase intent of dehulled and roasted kernels was evaluated. In-shell pecans were first subjected to hot water at 70, 80 and 90 °C for 8.6, 6.6 and 4.6 min respectively and kernels were later dry roasted at 160 °C for 10 min. The physicochemical properties of hot water treated and untreated nuts, before and after roasting were determined. Furthermore, consumer acceptance and purchase intent of the roasted kernels were determined. Hot water treatment, alone and subsequent roasting had minimal effect on pecans’ physicochemical properties. Consumers liked (P < 0.05) the colour and aroma of treated pecans. No effect (P > 0.05) of pre-treatment was observed on the acceptability of other sensory attributes. Safety claim increased treated pecans’ overall liking; however, it decreased purchase intent. Hot water treatment showed promise as a post-harvest microbial intervention strategy without affecting the physicochemical properties and consumer acceptability.     

Effect of different roasting methods on the proximate by composition,flow properties,amino acid compositions,colour, texture,and sensory profile of the chickpeas

Roasting is a common process for chickpeas to improve their texture, palatability, appearance, shelf-life, physical, and functional properties. This study aimed to determine the effect of different roasting methods (conventional, microwave, and microwave + conventional) on the proximate and amino acid compositions, powder properties, texture, and sensorial properties of the chickpeas. For this purpose three different roasting times (3, 5, and 7 min), microwave powers (100, 300, and 600 W), and microwave roasting + conventional roasting treatment (100 W + 250 °C, 300 W + 250 °C, and 600 W + 250 °C) were applied to raw chickpea samples. The moisture content and water activity values of roasted chickpeas were found to be lower than 7% (w.b.) and 0.50, respectively. The lower ash and protein contents, hygroscopicity value, wettability time and higher fat content and L* value were observed for control compared to roasted samples. The flowability behaviour of the samples was found at a fair level. Roasting methods significantly affected the amount of amino acids in chickpeas but do not reduce the nutritional quality of their proteins. The hardness value of chickpea samples from the suture and cheek angle was decreased parallel to the increase in the roasting temperature and time. The highest sensory scores in terms of general appeal were obtained from the combined group (300 W–250 °C) for 3 min.     

Impact of Roasting on the Chemical Composition and Oxidative Stability of Perilla Oil

Abstract: The impact of roasting was observed with regard to certain changes in the chemical components and oxidative stability of oil expelled from the roasted perilla seeds. The roasting times were established differently at each roasting temperature of 180, 200, and 220 °C. Trans fatty acids in perilla oil were detected, and the level detected increased as the roasting time increased. Moreover, the roasting of perilla seed led to an increase of 4 tocopherols, α‐, β‐, γ‐, and δ‐tocopherol, as well as phosphorus in the oil. The oxidative stability of the oils obtained after roasting increased during 60 d of storage at 60 °C. The rate of decrease of tocopherol in the oil from unroasted perilla seed was faster than that of the tocopherol in the oils from roasted perilla seeds during storage. Practical Application: The results reported in present research provide useful information that the producers of perilla oil could apply for their processing.     

Effect of roasting on colour and volatile composition of pistachios (Pistacia vera L.)

Pistachios have been roasted following the Iranian traditional method (soaking in salty water, drying and roasting at 135 °C). Three Iranian pistachio cultivars (Ahmad Aghaei, Akbari and Kaleghouchi) were compared for their volatile compositions, colour and odour intensity. Lightness decreased in the course of roasting, which resulted from Maillard reaction. Raw pistachios had lower concentrations of most volatiles than roasted. A total of twenty‐six compounds were detected in roasted pistachios; these included aldehydes, terpenes, alcohols and only two pyrazines and one furan. These mixtures of volatiles implied that the Iranian roasting system is very soft, and samples retained most of the vegetable notes from fresh pistachios and some roasted notes were generated as well (from 2‐ethyl‐5‐methylpyrazine and 2,6‐dimethyl‐3‐ethylpyrazine). Sample from cultivar Akbari presented higher odour intensity than those by the other two cultivars, due mainly to higher concentrations of pyrazines developed during the roasting step.     

Phytochemical profiles of black and yellow soybeans as affected by roasting

The current research aimed to compare the changes of phytochemicals, antioxidants, and anti-nutritional factors of yellow and black soybeans upon roasting. Yellow soybean was roasted at 210°C for 35 min and 230°C for 25 min, and black soybean was roasted at 210°C for 30 min and 230°C for 25 min. Isoflavones were significantly increased after the roasting process, while trypsin inhibitor was significantly decreased. The roasting process combined with the soaking process led to decrease in anthocyanin, soyasaponin, and antioxidant capacities. Black soybeans had more apparent variations in compounds than the yellow soybeans. For black soybeans, the processing under 230°C for 25 min presented more decrease in trypsin inhibitor and anthocyanin content. The roasting at a high temperature and short time produced products with a light color. Roasting combined with the soaking process had negative impacts on both yellow and black soybeans, but there were slight differences in the resultant compounds between different roasting temperatures.     

Compositional and Mechanical Properties of Peanuts Roasted to Equivalent Colors using Different Time/Temperature Combinations

Abstract: Peanuts in North America and Europe are primarily consumed after dry roasting. Standard industry practice is to roast peanuts to a specific surface color (Hunter L‐value) for a given application; however, equivalent surface colors can be attained using different roast temperature/time combinations, which could affect product quality. To investigate this potential, runner peanuts from a single lot were systematically roasted using 5 roast temperatures (147, 157, 167, 177, and 187 °C) and to Hunter L‐values of 53 ± 1, 48.5 ± 1, and 43 ± 1, corresponding to light, medium, and dark roasts, respectively. Moisture contents (MC) ranged from 0.41% to 1.70% after roasting. At equivalent roast temperatures, MC decreased as peanuts became darker; however, for a given color, MC decreased with decreasing roast temperature due to longer roast times required for specified color formation. Initial total tocopherol contents of expressed oils ranged from 164 to 559 μg/g oil. Peanuts roasted at lower temperatures and darker colors had higher tocopherol contents. Glucose content was roast color and temperature dependent, while fructose was only temperature dependent. Soluble protein was lower at darker roast colors, and when averaged across temperatures, was highest when samples were roasted at 187 °C. Lysine content decreased with increasing roast color but was not dependent on temperature. MC strongly correlated with several components including tocopherols (R² = 0.67), soluble protein (R² = 0.80), and peak force upon compression (R² = 0.64). The variation in characteristics related to roast conditions is sufficient to suggest influences on final product shelf life and consumer acceptability. Practical Application: Peanuts are typically dry roasted to a specified surface color for a given food application; however, it is possible to obtain equivalent colors using different temperatures. This simple observation led to the overall goal of this research which was to determine if peanuts roasted to equivalent surface colors using different temperatures are equivalent from a quality perspective. Several compositional and textural measurements important to product quality differed based on the temperature used to achieve a given roast color. Overall, this study suggests there is good potential to optimize peanut quality by simply adjusting the time/temperature profiles during roasting.     

Color and Volatile Analysis of Peanuts Roasted Using Oven and Microwave Technologies

Roasted peanut color and volatiles were evaluated for different time and temperature combinations of roasting. Raw peanuts were oven roasted at 135 to 204 °C, microwave roasted for 1 to 3 min, or combination roasted by microwave and oven roasting for various times and temperatures. Volatiles were measured using selected ion flow tube mass spectrometry. L* values were used to categorize peanuts as under‐roasted, ideally roasted, and over‐roasted. The total roasting time in order to achieve ideal color was not shortened by most of the combination treatments compared to their oven roasted equivalents. Oven before microwave roasting compared to the reverse was found to significantly increase the L* value. Peanuts with the same color had different volatile levels. Hexanal concentrations decreased then increased with roasting. Pyrazine levels increased as roasting time increased, although oven at 177 °C treatments had the highest and microwave treatments had the lowest levels. Volatile levels generally increased as roasting time or temperature increased. Oven 177 °C for 15 min generally had the highest level of volatiles among the roasting treatments tested. Soft independent modeling of class analogies based on volatile levels showed that raw peanuts were the most different, commercial samples were the most similar to each other, and oven, microwave, and combination roasting were all similar in volatile profile.     

Effect of roasting parameters on soy‐butter product quality

Effect of roasting temperature and time on the hardness, moisture content and colour of whole‐kernel of soybean was studied using response surface method (RSM). Colour of reference soy‐butter (RSB) was used to indicate the time and temperature suitable for roasting soybean kernels to prepare soy‐butter (SB). Temperature (160 °C) and time (90 min) for roasting were identified, soybean kernels were roasted, subsequently made into SB and compared with RSB on the basis of nutrient content, particle size, colour and rheology. SB contained 45 g% protein and 34 g% fat on dry matter basis. There was a significant difference (P < 0.05) between RSB and SB on the basis of L* values, D_3,2 and D_4,3. Rheology showed that SB samples behaved like a viscoelastic material. The mean apparent viscosity was significantly different (P < 0.0001) between SB (7.18 Pa.s) and RSB (4.72 Pa.s) which may be due to the significant difference in the particle size distribution (PSD). The Herschel‐Bulkley model could successfully explain the rheological behaviour of SB.     

Optimisation of sunflower oil deodorising: balance between oil stability and other quality attributes

The effect of deodorising on basic quality attributes of sunflower oil (free fatty acids, colour, oil stability, total tocopherols) was investigated. The results revealed that the levels of all these quality attributes decreased significantly during the deodorising step. The processing parameters of sunflower oil deodorisation were optimised using response surface methodology. The results revealed the effects of process parameters (temperature, time) on free fatty acids (FFA), colour (LCY and LCR), oil stability index (OSI) and total tocopherols (VE). These new models can be used as a tool to identify optimum deodorisation conditions within chosen constraints. Based on the optimisation of high oil stability with minimum retained FFA and colour, deodorisation parameters can be defined. At a constant vacuum, 3 mmHg vacuum, a temperature range of 200–250 °C and deodorisation time of 30–90 min were defined. An optimum temperature and time appear to be 218–224 °C and 59–64 min, respectively.     

Kinetic of Color Changes in Almond (Akbadem Variety) During Roasting and Storage

In this research, the color change kinetics of the Akbadem variety during roasting and storage processes was investigated. The roasting process was carried out at three different temperatures (150, 160, and 170°C) and four different times 10, 20, 30, and 40 min. Then, roasted samples were separated in two groups and stored for 6 months in 4 and 22°C. All of the color parameters reactions during roasting and storage took place according to first order reaction kinetics. L- and hue angle-values tended to decrease linear significantly during roasting. The L-values of Akbadem samples roasted at 150, 160,and 170°C for 40 min was determined as 52.34 ± 2.53, 47.96 ± 1.35, and 43.17 ± 0.09, respectively. The highest Ea-value was determined on the L-value as 14.80 ± 4.26. The a, b, ΔE, metric chroma (C), and metric saturation (S) values increased during roasting. L-, C-, a-, b-, and S-values tended to decrease linear significantly during storage. The L-, a-, and b-values of Akbadem samples which were roasted at 170°C and stored at 4°C for 6 months were decreased from 43.17 ± 0.09, 14.25 ± 0.026, and 29.53 ± 0.06 to 34.91 ± 0.13, 10.06 ± 0.15, and 15.93 ± 0.12, respectively. According to sensory analysis, the panelists gave low scores as taste (1.9 ± 0.88), color (2.1 ± 0.57), and flavor (2.4 ± 0.7) for Akbadem samples roasted at 170°C for 40 min. ΔE was increased during storage Ea-values were decreased during roasting and storage at 4 and 22°C for 6 months.