Roasting Techniques Research Articles

Effects of Variable-Temperature Roasting on the Flavor Compounds of Xinjiang Tannur-Roasted Mutton.

This study investigates the effect of variable-temperature roasting on the flavor compounds of Xinjiang tannur-roasted mutton. Gas chromatography coupled with ion mobility spectroscopy (GC-IMS) was used to compare and analyze the volatile components and flavor fingerprints of Xinjiang tannur-roasted mutton using variable-temperature electrically heated air roasting (VTR), constant-temperature electrically heated air roasting (EHAR), and constant-burning charcoal roasting (BCR) techniques. The changes in fatty acids and free amino acids in Xinjiang tannur-roasted mutton under different roasting conditions were compared. By using GC-IMS analysis, 11 flavor compounds, including 4-methyl-3-penten-2-one, isoamyl propionate, trans-2-heptenal, trans-2-heptenal, 2-hexanone, n-hexanol, 2-hexenal, 2-ethylfuran, and ethyl 2-methylbutanoate, were identified as characteristic volatile compounds in the temperature-controlled electrothermal roasting of Xinjiang tannur-roasted mutton using the following conditions: 0-4 min, 300 °C; 5-10 min, 220 °C; and 11-17 min, 130 °C (VTR3). Through principal component analysis, it was found that the substances with the highest positive correlation with PC1 and PC2 were n-hexanol and 3-methylbutanol. The sensory evaluation showed that VTR3 had high acceptability (p < 0.05) and a fat flavor (p < 0.05). There was no significant difference in the total fatty acid (TFA) content between the VTR3 and burning charcoal roast for 1-17 min at 300 °C (BCR3) (p > 0.05), but it was lower than that in the other experimental groups (p < 0.05). The lowest proportion of glutamic acid content in VTR3 was 22.44%, and the total free amino acid content in the electric thermostatic roasting for the 1-17 min, 300 °C (EHAR3) group (347.05 mg/100 g) was significantly higher than that in the other experimental groups (p < 0.05). By using Spearman correlation analysis, the roasting loss rate showed a highly significant negative correlation with essential amino acids (EAAs), non-essential amino acids (NEAAs), and total free amino acids (TAAs) (the correlation coefficients (r) were 0.82, 0.87, and 0.87, respectively) with p < 0.01. There was no correlation between changes in the free amino acid content and fatty acid content (p > 0.05). By using Differential scanning calorimetry (DSC) analysis, we also found that there was no significant difference in peak temperature (Tp) between the VTR3 and EHAR experimental groups (p > 0.05). Variable temperature electric heating can affect the flavor of lamb, and there are significant differences in the content of flavor precursors such as fatty acids and amino acids in Xinjiang tannur-roasted mutton.

Thermodynamic properties of MnV2O6 and Mn2V2O7 at high temperatures

MnV2O6 and Mn2V2O7 are the key compounds during the manganese salt roasting for extracting vanadium from vanadium bearing slag. Thermodynamic properties of MnV2O6 and Mn2V2O7 are dispensable to get insight into the multi-phase reaction mechanism and clarify the phase evolution. In this study, the MnV2O6 and Mn2V2O7 compounds were synthesized through solid-state roasting routes under a nitrogen gas atmosphere, and their crystal structure and thermodynamic properties were determined using X-ray powder diffraction, differential scanning calorimetry, and drop calorimetry. The enthalpy increments of MnV2O6 and Mn2V2O7 were experimentally measured for temperatures ranging from 573 K to 1023 K and 573 K to 1173 K, respectively, using drop calorimetry for the first time. Based on the experimentally measured enthalpy increments, the temperature dependence of the molar heat capacity of MnV2O6 and Mn2V2O7 was then derived. Furthermore, thermodynamic properties such as enthalpy, entropy, and Gibbs free energy were also calculated. Finally, the Gibbs free energy of the chemical reactions during the roasting of vanadium slag was evaluated, and compared with other roasting techniques.

The effect of different roasting techniques on bioactive compounds, fatty acids and element profiles of mahaleb seeds used as vanilla substitute in bakery products

SummaryIn this study, the effects of different roasting techniques on the oil content, bioactive compounds, antioxidant activity, phenolic components, fatty acid and mineral contents of mahaleb seeds, which can be used instead of vanilla, were investigated spectrophotometric and chromatographic systems. The oil quantities of the mahaleb seeds were assessed to be between 30.34% (control) to 34.08% (conventional oven). The total phenolic and flavonoid quantities were assigned to be between 34.37 (control) and 46.61 mg gallic acid equivalent (GAE/)/100 g (microwave) to 82.62 (conventional oven) and 94.21 mg quercetin equivalent (QE)/100 g (microwave), respectively. Antioxidant capacity values of untreated and roasted mahaleb seeds were assessed to be between 1.89 (control) and 2.03 mmol Trolox equivalent (TE) kg−1 (conventional oven). L* values of mahaleb seeds were established to be between 53.04 and 83.40, and a decrease was observed in L* values after heat treatment. Caffeic acid and rutin values of the mahaleb seeds were established between 344.84 (oven) and 641.86 (control) to 18.53 (control) and 146.52 mg/100 g (oven), respectively. The dominant fatty acids of the mahaleb oils were oleic, linoleic and palmitic acids. Phosphorus (P) and potassium (K) quantities of the mahaleb seeds were established to be between 4988.11 (control) and 5280.93 mg kg−1 (oven) to 8025.94 (oven) and 8462.66 mg kg−1 (microwave), respectively. The roasting process had an effect on the bioactive components, fatty acids and element contents of mahaleb seeds.

Use of flours from traditional pan and salt‐bed‐roasted Kodo grains in the production of breakfast cereal: Spatial, morphological, techno‐functional, structural, and rheological analyses

AbstractKodo millet, possesses the goodness of iron and low glycemic index, notably, its starch has inadequate application owing to retrogradation and low amylose content. Dry‐roasting seems worthy as an inexpensive pretreatment process to preserve desirable textural characteristics of whole cereal grains with peculiarity of moisture levels below 20% for a very short time. The aim of this work was to analyze indepth studies to explain morphological, techno‐functional, structural, and rheological transformation of Kodo starch components generated during roasting of conditioned whole kernels at 15% and 20% initial moisture content (IM). The micrographs displayed a honeycomb‐like structure in all roasted flours. The X‐ray diffraction intensity decreased and showed partial rupture to A‐type orthorhombic crystals of Kodo starch after roasting, while lamellar growth across the multilayer matrix was also generated (23° and 37.35°). The fusion of the starch granules with endosperm's macromolecules observed plausible techno‐functional, and rheological properties, emphasized as non‐nutritional properties substantially improved sensory attributes of food as an additive. Roasted flour at higher IM thus made it easier to integrate into instant ready‐to‐eat breakfast cereals of improved amylose content (23.69%–29.31%) with lowered water activity (.4671–.5170) of varied skin strength (196.17–1894.41 g), elasticity (4.03–10.21 mm), and cell size (164.03–1059.10 μm) detected from puncture‐test force measurement. The infrared absorbance band illustrated loss of peak at 1047 cm−1 and endosperm's expansion (195.34%–309.30%) lowered kernel hardness (42.3–17.78 N) indicated structural loss upon roasting, may significantly reduce milling cost, and provide a commercially pretreated readied kernel or flour for industrial applications.Practical applicationsKodo millet, of the Poaceae family thrives well in abiotic stress and scanty rainfall exhibit meager application owing to low amylose content. Applying preprocessing traditional roasting techniques upon moistened kernel, get popped cereal. Milling of such cereal retards subcellular loss, indicating increased amylose, water, and oil absorption with avid aroma. This is critical in the preparation of cost‐effective dietary formulations for children and geriatrics, thus making it easier for integration into ready‐to‐eat wholesome breakfast cereals.

Effect of Light, Medium, and Dark Roasting on Antioxidant Activity of Gununghalu Arabica Coffee (Coffea arabica L.)

Coffee is one of the popular drinks for Indonesian people. Coffee consumption in Indonesia has increased very rapidly. The influence of lifestyle and the increasing number of cafes and coffee shops contribute to the increase in coffee consumers. One downstream processing of coffee beans is roasting coffee beans, which consists of light, medium, and dark roasting. This study aimed to determine the antioxidant activity of Gununghalu Arabica Coffee (Coffea arabica L.) with Light Roasting, Medium Roasting, and Dark Roasting Techniques. This research is an experimental study, where the antioxidant activity analysis was carried out using the DPPH method (2,2-diphenyl-1-picrylhydrazyl). Gununghalu Arabica coffee with light, medium, and dark roasting techniques positively containing flavonoids, alkaloids, saponins, tannins, and terpenoids. The results showed that the IC50 value of Gununghalu Arabica coffee for light, medium, and dark roasting was 102.94 ppm, 70.66 ppm, and 87.66 ppm. The test results show that the antioxidant activity of Gununghalu Arabica coffee with light roasting techniques are moderate, while medium and dark roasting techniques are strong. The results of this study are expected to provide implications for the development of coffee processing techniques to have maximum health benefits.

Dietary Exposure to Polycyclic Aromatic Hydrocarbons and the Probabilistic Health Risk Assessment of Eating Roasted Yams (Dioscorea Species) by African Population

The roasting of food is one of the oldest food preparation and preservation technologies. Although roasted foods have been associated with potential health hazards, this processing method is still used in many foods. This study was carried out to ascertain the health risks of ingesting white (Dioscorea rotundata), and bitter yam (Dioscorea dumetorum) roasted with firewood, charcoal, and charcoal augmented with PET bottles. The PAH content in all the roasted yam samples was identified and analyzed using gas chromatography-mass spectroscopy (GC-MS). A total of 8 PAHs were identified in both yam species; however, bitter yam roasted with augmented charcoal contained 9 PAHs. The total EDI showed that bitter yam roasted with augmented charcoal (6.59E-1) had the highest PAH content while white yam roasted with only charcoal contained the lowest (1.27E-1). The hazard quotients and indexes revealed that bitter yam had the highest HQ in all the roasting methods except for napathalene, fluoranthene and benzo (a) pyrene in samples roasted with charcoal. The HI for both species in all the roasting methods was above 1 (&gt;1), while firewood produced the highest HI. Benzo (a) anthracene was the most potent PAH identified across the yam species and the roasting techniques. The evaluated ILCR showed that dibenzo (a, h) anthracene identified in white yam smoked with charcoal had the highest tendency to cause cancer (6.38E-1) while the least PAH was acenaphthylene (3.35E-6) which was seen in bitter yam roasted with charcoal. Therefore, it is necessary to inform the consumers of the possible health implications associated with consuming roasted yams and especially yam roasted with augmented charcoal

Roasting conditions on metabolic profile of black honey arabica coffee (Coffea arabica)

A post-harvest preparation for coffee is black honey process. The post-harvest procedure of roasting affects the flavor and aroma of coffee. This study aimed to examine the color, caffeine content, water content, ash content, protein content, carbohydrate content, fat content, analysis of fatty acid content, and cupping test of black honey arabica coffee that treated under different roasting condition. The analytical observation on color, caffeine content, water content, ash content, protein content, carbohydrate content, fat content, fatty acid was conducted and sensory analysis was applied for cupping test. The findings showed that the differences in roasting techniques have a significant influence at the 5% level on the color, moisture content, ash content, carbohydrate content, and fat content of black honey arabica coffee but have no significant impact on the protein content. According to the findings of the cupping test, the best roasting technique was a medium roast. The roasting process under medium roast conditions was known to give the attributes of a brown color due to the Maillard reaction, a specific aroma possibly coming from caramel, citrus, cassia vera and honey, a specific sour taste and a long after taste. The medium roast process has a specific fatty acid profile consisting of myristic acid, palmitic acid and elaidic acid. These characters were the characteristic determinant of the taste produced by Arabica coffee which is processed using black honey post-harvest techniques and roasted with medium conditions.

Fluidized bed roasting modifying the microstructure of cocoa nibs and improving cocoa butter quality

AbstractThe extraction of butter from cocoa seeds involves various processing steps that weaken the lipid‐storing cell walls of cocoa cotyledons. Roasting is particularly critical, making cocoa nibs porous and brittle. In this study, the degree of disruption of the microstructure of cocoa nibs, and the quality and aroma profile of cocoa butter, were evaluated using two roasting techniques, forced convective oven, and fluidized bed. Fluidized bed roasting, recognized for its energy efficiency and low‐carbon footprint, was 12 times faster than oven roasting. This technique allowed a rapid release of steam when parenchyma cell walls were still in a glassy state, while oven roasting caused gradual physical modification allowing the cell wall to become more elastic. Consequently, small pores expanded and coalesced to produce larger pores. X‐ray tomographic analysis showed a total porosity in unroasted cocoa nibs of 8.5 ± 2.0% (vol/vol), which was doubled upon oven roasting and triplicated upon fluidized bed roasting. The higher porosity in fluidized‐bed‐roasted nibs was reflected in the lowest densities and highest cocoa butter yield. Cocoa butter obtained from fluidized‐bed roasted cocoa showed a higher presence of pyrazines and 3‐methylbutanal, and a lower concentration of hydroperoxides, thus enhancing the chocolate flavor and quality. In this paper, we proved that the pore structure of cocoa nibs is a key quality descriptor of roasting processing, and we concluded by quality considerations that fluidized bed roasting technique should be preferred for cocoa nibs roasting over conventional roasting.

Optical Properties Comparison of Carbon Nanodots Synthesized from Kangkung (Ipomoea aquatica) with Deep Frying and Roasting Techniques

Carbon nanodots (Cdots) have many unique properties such as luminescence that can be utilized in various fields. The purposes of this study are to synthesize Cdots from kangkung (Ipomoea aquatica) through frying and roasting techniques and compare the optical properties of the Cdots using UV-Vis, PL, and FTIR. Three stages of synthesizing process of Cdots, i.e.: preparing the kangkung powder (root, stem, leaf) and synthesizing the Cdots through frying and roasting techniques. Each part (root, stem, and leaf) was heated in an oven at 250 oC for 2 hours and mashed into powder. The frying method was done by frying 15 g of the powder in 120 ml oil for 5 minutes at 88 oC, filtered, and dissolved in n-hexane. In addition, the roasting method was done by frying the powder without oil as much as 15 g for 5 minutes, dissolved in 120 ml of distilled water, and then filtered. The UV-Vis characterization showed one absorbance peak for Cdots via frying and roasting techniques at 293 nm to 296 nm and 262 nm to 282 nm, respectively. The Cdots through frying and roasting techniques produce red and green luminescence, respectively. The FTIR characterization showed the presence of C=C and C=O functional groups, which are the core and surface state of the Cdots by frying technique, while the samples via roasting technique showed only the core. It can be concluded that the Cdots samples obtained from frying and roasting methods have different optical properties. The frying method produces Cdots with longer wavelength at the absorbance peak in the UV-Vis test compared to the roasting method. Moreover, the frying and roasting methods produce different color luminescence.

Reflections on nutrition in biological anthropology.

Reflections on nutrition in biological anthropology.

Static Hot Air and Infrared Rays Roasting are Efficient Methods for Aflatoxin Decontamination on Hazelnuts.

Aflatoxins are a group of secondary metabolites produced by members of Aspergillus Section Flavi that are dangerous to humans and animals. Nuts can be potentially contaminated with aflatoxins, often over the legal threshold. Food processes, including roasting, may have different effects on mycotoxins, and high temperatures have proven to be very effective in the reduction of mycotoxins. In this work, two different roasting methods—traditional static hot air roasting and infra-red rays roasting—were applied and compared for the detoxification of hazelnuts from Italy and Turkey. At the temperature of 140 °C for 40 min of exposure, detoxification was effective for both roasting techniques. Residual aflatoxins after infra-red rays treatments were lower compared to static hot air roasting. On Italian hazelnuts, residual aflatoxins were lower than 5%, while for Turkish hazelnuts they were lower than 15% after 40 min of exposure to an infra-red rays roaster. After roasting, the perisperm was detached from the nuts and analyzed for aflatoxin contents. Residual aflatoxins in the perisperm ranged from 80% up to 100%. After roasting, the lipid profile and the nutritional quality of hazelnuts were not affected. Fatty acid methyl esters analyses showed a similar composition for Italian and Turkish hazelnuts.

Industrial Applications of Selected JFS Articles

Industrial Applications of Selected <i>JFS</i> Articles

Effect of cultivar and roasting technique on sensory quality of Bierzo roasted pepper

Pepper (Capsicum annuum L.) is one of the main horticultural products in the world. Roasted pepper is a high quality transformed product in the Iberian Peninsula, and obtained the recognition of 'Protected Geographical Indication' (PGI) of 'Pimiento Asado del Bierzo' in 2002. Roasted pepper has been traditionally processed with a steel-sheet hob. However, there are no data available about the effect of roasting technique in the quality of roasted pepper. The objective of this work was to compare the sensory quality of roasted pepper using industrial roasting techniques. Sensory properties that showed significant differences between roasting techniques were colour, thickness and charred remains (appearance descriptors), bitterness (taste descriptor) and smokiness (after-taste descriptor). Higher value of descriptors such as colour, charred remains and smokiness for peppers elaborated in a rotary oven, helped roasted pepper to reach a higher level of overall quality, although rotary oven samples reached the lowest roast yield. Roasting technique, rather than landrace, had the greatest effect on the sensory quality of roasted pepper, so the rotary oven was the roasting technique that achieved the highest quality score. This will contribute to improve sensory quality and marketing of PGI 'Pimiento Asado del Bierzo' in high quality markets.

Effect of two different roasting techniques on the Ochratoxin A (OTA) reduction in coffee beans (Coffea arabica)

The roasting of green coffee beans (Coffea arabica) artificially contaminated by Ochratoxin A (OTA) after inoculation with Aspergillus westerdijkiae was carried out with two different roasting techniques (Rotating Cylinder [RC] and Fluidized Bed [FB]). The green coffee beans were contaminated at two different toxin levels (L1=5.3μgkg−1 and L2=57.2μgkg−1). Different roasting points (light, medium, dark and very dark) were set according to the L∗ color coordinate. The cylinder roasting conditions were 0, 3, 6, 9, 12, and 15min at 230°C and the fluidized bed roasting conditions were 0, 0.9, 1.7, 2.6, 3.5 and 4.3min, at 230°C. The roasted beans were compared for their physical properties (bean swell and weight loss) as well as for their residual OTA content. The results indicated that the OTA reduction was similar for the two contamination levels: 95.1% and 97.2% with the rotating cylinder and 81.3% and 79.2% with the fluidized bed at the maximal roasting time. The OTA degradation kinetics differed between the two processes. The complete degradation of OTA within the limit of this study (230°C) was not observed but the rotating cylinder roasting was the most efficient technical process for the OTA reduction in a commercial dark roasted coffee (88%).

Effect of processing steps on the physico-chemical properties of dried-seasoned squid

The effects of processing steps on the physico-chemical properties of dried-seasoned squid were studied using two kinds of squids. Browning was observed as indicated by an increase in yellowness ( b ∗ value) during the semi-drying and roasting step. The temperature and time of heating and type of roasting, as well as the material itself were the key factors influencing the browning. A high level of trimethylamine oxide (TMAO), and low contents of trimethylamine (TMA) and dimethylamine (DMA) were detected in the raw material. TMAO gradually decreased during the processing, while TMA, DMA and formaldehyde (FA) increased significantly especially in boiled meat. The temperature of boiling was the most crucial factor impacting the production of FA. FA could be greatly decreased during the cooling process by washing with water or changing the roasting techniques. Therefore, to improve the quality of dried-seasoned squid, more attention should be paid to the temperature and roasting techniques during the processing.

On the use of photobleaching to reduce fluorescence background in Raman spectroscopy to improve the reliability of pigment identification on painted textiles

Subjecting a specimen of red lead watercolour paint on silk to photobleaching was demonstrated to be a simple means by which to engineer a reduction in the magnitude of the fluorescent background that was approximately exponential with time, with a corresponding improvement in the signal to noise ratio of the Raman spectrum, thus rendering the characteristic peaks more easily visible and allowing more confident identification of the pigment. However, relative heights of the Raman peaks obtained from the sample were seen to alter progressively as a result of irradiation, indicating that some component of the sample was undergoing degradation that may result in longer-term damage to a fragile historic artefact. It was also shown that crystals of the lead monoxide pigment massicot were present in the samples of red lead on a painted silk artefact dating from 1750. It is concluded that this was either due to deliberate mixing of pigments by the artist, contrary to historic records, or as a result of the roasting techniques used to create red lead pigments at the time and not due to thermal degradation of the pigment during Raman analysis.

Mercury speciation in tailings of the Idrija mercury mine

Five hundred years of mercury (Hg) mining activity in Idrija, Slovenia caused widespread Hg contamination. Besides Hg emissions from the ore smelter, tailings have been found to be the major source of river sediment contamination. In the present study, solid phase binding forms and the aqueous mobility of Hg have been investigated in tailings of the Idrija Hg mine by means of a pyrolysis technique and aqueous Hg speciation. Results show that Hg binding forms differ with the age of the tailings due to the processing of different ores with different roasting techniques. In older tailings, the predominant Hg species is cinnabar (HgS), due to incomplete roasting, whereas in tailings of the 20th century the amount of cinnabar in the material decreased due to a higher efficiency of the roasting process and the increasing use of ores bearing native Hg. In younger tailings, metallic Hg (Hg 0) sorbed to mineral matrix components such as dolomite and Fe-oxyhydroxides became the predominant Hg binding form in addition to unbound Hg 0 and traces of HgO. Leaching tests show that in younger tailings high amounts of soluble Hg exist in reactive form. In older tailings most of the soluble Hg occurs bound to soluble complexes. It might be assumed that in the long term, matrix-bound Hg 0 could be bound to humic acids derived from soils covering the tailings. This means that, despite the lower total Hg concentrations found in the younger tailings, the long-term risk potential of its mobile matrix-bound Hg 0 is higher than that of older tailings bearing mostly immobile cinnabar.

Acceptability and viscosity of low cost home processed supplementary foods developed for preschool children

Four supplement mixtures using whole wheat, pearl millet, bengal gram, green gram, groundnuts and amaranth leaves were developed employing roasting and malting techniques. Malting used in the formation of the supplements reduced significantly hot paste viscosity of all the four supplements and increased their nutrient density per unit volume. The organoleptic trials conducted on rural mothers revealed that taste, texture, colour, aroma, appearance and overall acceptability of all the four supplements were found to be excellent with mean overall acceptability. Children did not develop any GIT disorders after consuming the products. Trained panelists found all the four supplements acceptable as indicated by a nine point hedonic scale.

Acceptability and viscosity of low cost home processed supplementary foods developed for pre-school children.

Four supplement mixtures using whole wheat, pearl millet, bengal gram, green gram, groundnuts and amaranth leaves were developed employing roasting and malting techniques. Malting used in the formation of the supplements reduced significantly hot paste viscosity of all the four supplements and increased their nutrient density per unit volume. The results of organoleptic trials conducted on rural mothers revealed that taste, texture, colour, aroma, appearance and overall acceptability of all the four supplements were excellent with mean scores of overall acceptability (9.77, 9.33, 9.11 and 8.75) for supplements I, II, III and IV, respectively. Children did not develop any GIT disorders after consuming the products. Trained panelists found all the four supplements acceptable as indicated by Nine point hedonic scale.