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.     

Determination of Enterococcus faecium thermal reduction in normal and high oleic peanut products

During processing, peanut butter can become contaminated with pathogenic bacteria (e.g., Salmonella). The introduction of an additional heat treatment step after roasting can help inactivate these microorganisms. In this study, trials were conducted to determine Enterococcus faecium (Salmonella surrogate) reduction rates during the roasting of high oleic (HO) peanuts and heat-treatment of normal oleic (NO) and HO peanut butters. HO peanuts were inoculated with E. faecium and roasted in a convection oven at 190°C. There was a 2 and 6 log CFU/g reduction at 300 and 480 s, respectively. D-values for HO peanut butter at 110, 120, and 125°C were 438.9, 165.1, and 80.6 s, respectively. The z-value was calculated to be 20.8°C. There was no significant difference in D-values and z-values between NO and HO peanut butter. In a pilot scale experiment, HO peanut butter was inoculated with E. faecium and agitated in a heated mixer for 21.5 min. E. faecium was reduced by 5.1 log CFU/g after 16.5 min with no apparent change in viscosity or texture. This study demonstrated that significant reductions in E. faecium can be achieved during roasting and through an additional heat-treatment step.     

Tocopherol content,peroxide value and sensory attributes in roasted peanuts during storage

The objective of this study was to determine changes in tocopherol content, peroxide value (PV) and sensory attributes from roasted peanuts during storage at 40 °C. There were no differences in tocopherol contents between roasted and raw peanuts except in α‐tocopherol content that decreased after roasting. All tocopherol contents decreased during storage. On the contrary, lipid oxidation indicators such as PV and the intensity ratings of oxidised and cardboard flavour increased during storage. On the other hand, the intensity ratings of roasted peanutty flavour decreased with storage time. Good correlations were observed between tocopherol contents and PVs. Tocopherol contents could be used as indicator of oxidative state in peanut products.     

Impact of roasting conditions on the quality and acceptance of the peanut paste

Roasting is the main processing step performed to improve sensory and conservative properties of peanuts. The objective of this study was to evaluate changes in peanut oil and paste during roasting at different temperatures in a conventional oven (80, 110, 140, 170, and 200°C) and microwave. The increase in roasting temperature promoted reduction of L* value, b* value, and increases of a*, K₂₃₂, K_270, and acidity. For alpha (α), gamma (γ), and delta (δ) tocopherols, as well as fatty acids, less degradation were observed at the roasting temperature of 140°C. Paste acceptability greater than 70% was achieved with roasting at 140°C. Based on the results, 140°C was the optimal roasting temperature that achieved the best paste acceptance rates with the smallest changes in oil and tocopherol quality parameters.     

Effect of roasting conditions on color and volatile profile including HMF level in sweet almonds (Prunus dulcis)

Microwave, oven, and oil roasting of almonds were used to promote almond flavor and color formation. Raw pasteurized almonds were roasted in a microwave for 1 to 3 min, in an oven at 177 °C for 5, 10, 15, and 20 min; and at 135 and 163 °C for 20 min, and in oil at 135, 163, and 177 °C for 5 min and 177 °C for 10 min. Volatile compounds were quantified in the headspace of ground almonds, both raw and roasted, by selected ion flow tube mass spectrometry. Strong correlations were found between L value, chroma, and 5-(hydroxy methyl)-2- furfural; and were independent of roasting method. Raw almonds had lower concentrations of most volatiles than roasted almonds. Conditions that produced color equivalent to commercial samples were 2 min in the microwave, 5 min at 177 °C in the oven, and 5 min at 135 °C in oil. Microwave heating produced higher levels of most volatiles than oven and oil roasting at commercial color. Sensory evaluation indicated that microwave-roasted almonds had the strongest aroma and were the most preferred. Oil-roasted almonds showed significantly lower levels of volatiles than other methods, likely due to loss of these volatiles into the oil. Alcohols such as benzyl alcohols and strecker aldehydes including benzaldehyde and methional were at higher concentrations than other volatiles in roasted almonds. The oxidation of lipids to form alkanals such as nonanal and degradation of sugars to form furan type compounds was also observed. The Maillard reaction contributed to the formation of more of the total volatiles in almonds than the lipid oxidation reaction. PRACTICAL APPLICATION: The level of 5-(hydroxy methyl)-2- furfural (HMF), color, volatile profile, and sensory perception can be used to develop the best roasting method, time, and temperature for almonds. The rate of color development and the production of volatiles differ under different roasting conditions. Based on the color, volatile, and sensory assessments of the 3 almonds, the use of microwave technology as a process for roasting almonds reduces processing time and leads to an almond product with better flavor than oven or oil roasting.     

Evaluation of Various Methods for Roasting Frozen Turkeys

Frozen turkeys were roasted to a lower than normal final temperature (71.1°C, 160°F) by one of the following methods: (1) foil tent, 93.3°C (200°F) oven; (2) foil wrap, 93.3°C (200°F) oven; (3) foil tent, 162.8°C (325°F) oven; (4) roasting bag, 176.7°C (350°F) oven; (5) foil wrap, 204.4°C (400°F) oven; or (6) microwave oven. Birds roasted by low temperature roasting methods received highest ratings for most attributes. Basted birds were preferred for all eating quality attributes. Microwave roasted birds reached final temperature fastest and with least energy consumption, but were rated low in appearance and eating qualities, and often had undesirably pink thigh joints. Turkeys inoculated with Salmonella typhimurium and Clostridium perfringens vegetative cells were essentially sterilized by all roasting methods. These methods can be considered as convenient alternatives to conventional roasting procedures.     

Roasted Peanuts and Peanut Butter Quality are Affected by Supercritical Fluid Extraction

Roasted peanuts were extracted using supercritical CO₂ (413.6 bar, 50–60° for 0, 2 or 4 hr). Peanuts were evaluated for shatter, tristimulus color, shear-compression force, moisture, lipid content, and sensory attributes. Extracted nuts were prepared into peanut butter and evaluated for color, relative torque resistance ratio, and sensory attributes. Lipid content decreased from 51.6 to 40.6% during 4 hr extraction. SFE increased shatter, shear-compression force, and Hunter L-value, but decreased hue angle, roasted aroma intensity, moistness of mass, fracturability, and roasted flavor intensity of peanuts. SFE increased the relative torque resistance ratio, and adhesiveness of peanut butter but had little effect upon flavor. SFE may be useful to reduce peanut contaminants and lipids to produce value-added peanut products.     

Use of Electrolyzed Oxidizing Water for Quality Improvement of Frozen Shrimp

The bactericidal effect of electrolyzed oxidizing (EO) water was evaluated on Escherichia coli O157:H7‐inoculated and Salmonella‐inoculated shrimp. The shrimp were inoculated on day 0 and stored frozen at ‐20°C. Bacterial enumeration was done on days 0, 24, 49, and 119 of frozen storage. Acidic EO water at 40 ppm free available chlorine was as effective as aqueous chlorine of the same concentration and was significantly more effective (P < 0.05) than tap water in reducing pathogen load on the inoculated shrimp. Further reduction of pathogen numbers was observed after each frozen storage period. Prewashing with alkaline EO water did not enhance the bactericidal activity of the acidic EO water on the shrimp. The washed acidic EO water of the inoculated shrimp had a nondetectable bacterial population compared with treated aqueous chlorine, alkaline EO water, and tap water. Non‐inoculated shrimp subjected to similar treatments were served cooked or uncooked to a minimum of 10 experienced panelists for sensory evaluation on days 0, 24, 49, and 119 of frozen storage. The cooked shrimp were evaluated for the presence of off‐odor, juiciness, tenderness, shrimpy flavor, aftertaste, and overall acceptability; whereas the raw shrimp were evaluated for color, firmness, presence of off‐odors, melanosis, and overall acceptability. Raw shrimp thawed from each frozen storage period were stored at refrigeration temperature (4 °C) for 3 d to observe for melanosis. No difference of sensory attributes was detected among the various treatment groups. Therefore, acidic EO water can be used as an effective disinfectant to replace aqueous chlorine for thawing shrimp blocks.     

Comparison of Sound and Shriveled Peanut Kernels from Sized Commercial Lots

Sound and shriveled peanut kernels obtained from sized commercial lots were subjected to compositional analyses, and roasted at 150°C for 25 min before subjecting to analysis of sugars, total and free amino acids, protein patterns and oven test. Shriveled raw peanuts contained higher moisture, free amino acid, sucrose, and glucose, and lower lipid contents than sound peanuts. Shriveled kernels underwent greater decreases in total and free amino acids, less increase in sucrose, and more protein denaturation after roasting. Shriveled kernels were more susceptible to oxidative deterioration.     

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.     

Effect of storage on chemical and sensory profiles of peanut pastes prepared with high‐oleic and normal peanuts

BACKGROUND: Peanut paste and peanut butter have high oil contents and are thus susceptible to developing rancidity and off‐flavours through lipid oxidation. Preservation of the chemical and sensory quality of these products is one of the main problems in the peanut industry. The purpose of this study was to compare the chemical and sensory stability of peanut paste prepared with high‐oleic peanuts (cv. Granoleico, GO‐P) with that of peanut paste prepared with normal peanuts (cv. Tegua, T‐P) from Argentina. RESULTS: Chemical (peroxide and p‐anisidine values and conjugated dienes) and sensory (roasted peanutty, oxidised and cardboard flavours) indicators of lipid oxidation were measured in peanut pastes stored at 4, 23 and 40 °C. Chemical indicator values and oxidised and cardboard flavours showed lower increments in GO‐P than in T‐P during storage. T‐P had significantly higher peroxide value than GO‐P. Roasted peanutty flavour showed a lower decrease in GO‐P. Peanut paste prepared with high‐oleic peanuts had four (at 4 °C), two (at 23 °C) and three (at 40 °C) times longer shelf‐life than peanut paste prepared with normal peanuts. CONCLUSION: These results indicate that high‐oleic Granoleico kernels provide peanut paste with higher protection against lipid oxidation. Copyright © 2010 Society of Chemical Industry     

花生焙炒过程中红衣对毛油品质影响的研究

将花生进行3种不同加工方式的处理(包裹红衣焙炒,焙炒后脱除红衣,脱除红衣后焙炒)后提取花生毛油,对所提取的花生毛油进行品质分析,以研究花生红衣脱除与否以及红衣脱除和焙炒的顺序对花生毛油品质的影响。结果表明:随着焙炒温度升高、焙炒时间延长,花生毛油色泽逐渐加深;花生红衣对花生毛油的色泽未造成影响;包裹红衣焙炒组具有最高的酸败风险;相同焙炒条件下,花生毛油的脂肪酸、反式脂肪酸和甘油三酯组成都无明显差异;花生毛油的脂肪酸组成、反式亚麻酸含量、甘油三酯组成均不受焙炒温度和焙炒时间变化的影响,花生毛油反式油酸、反式亚油酸含量和反式脂肪酸总量则随焙炒温度升高、焙炒时间的延长呈现攀升趋势。     

Changes in Roasted Peanut Flavor and Other Quality Factors with Seed Size and Storage Time

Peanut seed size and time in storage have been investigated as to their influence on roasted flavor, peanut butter color. Blanchability of roasted peanuts, oxidative stability and iodine value of raw peanuts. Seed size had a significant effect on roasted flavor and peanut butter color with constant roasting time and with roasting to a uniform peanut butter color. Blanchability of the seed after roasting was also significantly affected by seed size as well as storage time. Oxidative stability of the raw peanuts showed a general tendency to decrease with seed size and storage time. Iodine values were significantly higher in the smallest seed size but storage time did not affect iodine values. The data suggest that inferior quality is being introduced into marketing channels through use of a 5.95 mm screen size as a minimum for grading U.S. No. 1 Virginia-type peanuts.     

Effects of processing conditions and packaging material on the quality attributes of dry‐roasted peanuts

Five different processing conditions of raw shelled unblanched peanuts were investigated. The first two treatments involved soaking the peanuts in tap water for 10 and 30 min respectively, then mixing thoroughly with dry NaCl before roasting. Another two treatments involved soaking the peanuts in saturated brine solution for 10 and 30 min respectively before roasting. Unsalted roasted peanuts served as the control. Packaging and storage studies were carried out by packaging the differently treated dry‐roasted peanuts in four different packaging materials and storing them under three different relative humidities for 3 months at ambient temperature. Proximate composition, NaCl content, peroxide value and thiobarbituric acid value were determined and sensory evaluation tests were carried out. Salting was found to improve the taste, flavour and overall acceptability of dry‐roasted peanuts but had no effect on shelf‐life. Peanuts treated in saturated brine solution for 30 min before roasting were the most preferred. The control packaging material, 18 µm transparent polyethylene, was found to be inadequate for protecting the quality attributes of dry‐roasted peanuts, with mould growth being observed on the 42nd day of storage at 80% relative humidity. However, acceptable results were obtained with 45 µm transparent polypropylene. The mean sensory scores and objective tests were found to be negatively correlated. © 2002 Society of Chemical Industry     

Flavor and Oxidative Stability of Peanut-Sesame-Soy Blends

Five spreads were formulated from roasted high‐oleic acid peanuts and sesame paste (HOPS), normal‐oleic acid peanuts and sesame paste (NOPS), high‐oleic acid peanuts, sesame paste and soy (HOPSS), normal‐oleic peanuts, sesame paste and soy (NOPSS), and normal‐oleic acid peanuts only (NOP). Spreads were evaluated during 12 wk at 40 °C for sensory attributes: roast peanut, sesame, sweetness, bitterness, cardboardy, and painty. Roast peanut and sesame flavor generally decreased, and HOPSS and NOPSS had lower roasted peanut flavor. Cardboardy and painty increased in NOP, and HOPS had the lowest cardboardy and painty flavors. Peroxide values increased, with the highest value in NOP and lowest in HOPS. Sesame paste limited oxidation in products containing NOP and soy.     

SENSORY ATTRIBUTES AND THIAMINE CONTENT OF ROASTING CHICKENS COOKED IN A MICROWAVE, CONVECTION MICROWAVE AND CONVENTIONAL ELECTRIC OVEN

Fresh whole roasting chickens were cooked to an internal temperature of 79°C (175°F) in either a microwave, convection microwave or conventional electric oven. The sensory attributes of breast meat samples from chickens cooked in the three ovens were evaluated by untrained and laboratory panels. Untrained panelists found convection microwave cooked samples to be more acceptable in terms of juiciness than microwave cooked samples. Laboratory panelists rated the chicken cooked in the conventional oven as significantly more tender and juicy but similar in flavor intensity to chicken cooked in the microwave ovens. Thiamine retention on a dry weight basis ranged from 77% in conventionally cooked chicken breasts to 98% in microwave cooked chicken legs.     

INSTRUMENTAL AND SENSORY EVALUATION OF TEXTURAL CHANGES DURING ROASTING OF CASHEW KERNELS

Textural changes in cashew kernels roasted in hot‐air oven at controlled temperatures in the range of 140–180C for 30–120 min were studied using both instrumental and sensory evaluations. The Kramer shear force decreased exponentially, whereas the color lightness index and the total color difference exhibited linear relationships with roasting time at all temperatures. The changes in sensory parameters such as acceptability, appearance and taste were adequately described by third‐degree polynomials. The optimum roasting conditions for cashew kernels based on hedonic sensory evaluations were determined to be 140C–33.3 min, 160C–11.2 min and 180C–5.7 min, and resulted in similar values of Kramer shear force and color lightness index estimated from the developed models. The instrumental measurements could be used for monitoring the roasting process to produce optimally roasted cashew kernels.     

Preserving sensory attributes of roasted peanuts using edible coatings

Peanut products are susceptible to develop rancid and off‐flavours through lipid oxidation. Preservation of these products is one of the problems in the peanut industry. The purpose of this work was to determine the sensory and chemical stability of roasted peanuts (RP) coated with different edible coatings: carboxymethyl cellulose (RP‐CMC), methyl cellulose (RP‐MC) or whey protein (RP‐WPI) during storage. Sensory attributes and chemical indicators (peroxide and p‐anisidine values, and conjugated dienes) of lipid oxidation were measured during storage. Chemical indicator values and intensity ratings of oxidised and cardboard flavours had lower increase in RP‐CMC, RP‐MC and RP‐WPI during storage than in RP, whereas roasted peanutty flavour showed a lower decrease. The stability of RP‐CMC is about a double longer with respect to RP. These results indicate that edible coatings preserve the sensory properties of roasted peanuts. Carboxymethyl cellulose exhibited the best protecting effect on this product.