Sensory Quality of Turkey Breasts and Energy Consumption for Roasting in A Convection Oven and Reheating in Infrared, Microwave, and Convection Ovens

Determinations were made of the sensory quality of turkey breasts and energy consumption in roasting in a convection oven at 163°C and 105°C and reheating in microwave, infrared, and convection ovens. Significantly less energy was used for roasting at 105°C and in reheating in the microwave oven. Freshly roasted turkey was scored significantly higher for overall quality, lack of stale flavor, moistness of appearance, and lack of surface browning than any reheated sample, and turkey roasted at 105°C was significantly less brown and softer after reheating. Roasted aroma was less after reheating in the microwave, and fresh aroma greatest after reheating in the convection oven, but no other significant differences were related to oven.     

Sensory Quality of Turkey Rolls Roasted and Held in an Institutional Convection Oven With and Without Chilled Storage

Sensory quality of turkey rolls was determined related to: roasting to 77°C in a convection oven at 105°C, 136°C and 165°C; 0, 60, and 120 min holding in a convection oven; and 0 and 24 hr chilled storage. Turkey aroma and flavor were significantly greater after 120 than 0 min holding time. Juiciness was significantly greater for turkey roasted at 105° than at 136° or 165°C, at 0 than after 60 or 120 min holding, and was influenced by the interaction of roasting temperature with cold storage and holding time; and cold storage with time for holding hot turkey. Cold storage alone had no effect on juiciness, and neither texture nor off-flavor were affected by any of the factors in the study.     

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.     

Turkey Quality as Affected by Ovens of Varying Energy Costs

Energy consumption of microwave, convection, and conventional ovens was monitored as boneless turkey roasts were cooked. The microwave and convection ovens were more energy efficient than was the conventional oven. Total cooking losses and expressible moisture indices did not differ among the roasts. Shear values for microwave roasts were higher than those for convection roasts but were similar to those of conventional roasts. An experienced sensory panel found no differences in doneness, appearance, juiciness, and flavor among roasts after they had been stored in a refrigerator overnight but did find that the microwave roasts were less tender than were the others. A 72-member consumer panel did not express any preferences among the roasts in a multiple-paired comparison test.     

Sensory Quality and Energy Use for Scrambled Eggs and Beef Patties Heated in Institutional Microwave and Convection Ovens

Scrambled eggs (96 portions) and beef patties (96 portions) were heated in institutional microwave and convection ovens to determine energy use in heating and sensory quality of food. For both products, significantly (P < 0.01) more energy (BTU) was used for heating in the convection than in the microwave oven and respective amounts (BTU) were 28658.7 and 9385.7 for eggs; 31313.3 and 9365.0 for beef patties. All scores for sensory quality were significantly (P < 0.01) higher for eggs heated in the microwave than in the convection, but for beef patties, scores were higher for all characteristics and significantly (P < 0.01) higher for appearance, flavor, and general acceptability after heating in the convection rather than the microwave oven.     

Sensory Characteristics of Postmortem Papain Injected Turkey Cooked Conventionally or by Microwaves

Sensory characteristics of papain-injected turkey breast muscle cooked in microwave or conventional ovens were evaluated by a panel. Off-flavor and mealiness developed in intact turkey muscles injected with papain, but those levels of papain were not sufficient to tenderize the muscle. Samples cooked in conventional ovens had greater roast turkey flavor and were less juicy than samples cooked in microwave ovens.     

Sensory Quality of Spaghetti with Meat Sauce After Varying Holding Treatments and Heating in Institutional Microwave and Convection Ovens

Sensory quality of spaghetti was determined for a freshly prepared sample and after heating in institutional microwave and convection ovens following holding 1 hr chilled; 24 hr chilled; 24 hr frozen; 24 hr frozen, 24 hr chilled. Differences attributable to holding treatment occurred in moistness; in clumping, firmness and chewiness of pasta; and in overall ratings. Samples held 1 or 24 hr chilled had better scores than those held 24 hr frozen or 24 hr frozen, 24 hr chilled. Spaghetti heated in the microwave compared to the convection oven had greater fat separation, clumping, greasiness, firmness, and chewiness.     

不同复热方式对猪耳朵制品挥发性风味和脂肪氧化的影响

利用吹扫捕集-热脱附-气相色谱-质谱联用结合嗅闻技术和硫代巴比妥酸反应活性物质（thiobarbituric acid reaction substances,TBARS）值对不同复热方式（巴氏、水蒸、微波、高温）处理的猪耳朵制品挥发性风味物质含量和脂肪氧化程度进行分析。结果表明,不同复热处理样品共鉴定出58?种风味物质,醛类和烃类物质含量较高;基于风味活性值分析,己醛、辛醛、壬醛、癸醛、（E）-2-癸烯醛、（E,E）-2,4-癸二烯醛、1-辛烯-3-醇、苯酚和丁香酚对复热风味贡献较大;基于主成分分析,水蒸复热样品风味变化不明显;复热猪耳朵制品过熟味（warmed-off flavor,WOF）以亚麻籽油味为主,带有轻微的金属味和酸败味;巴氏复热显著增加WOF关键风味因子含量和TBARS值;微波复热能够较好避免复热WOF的形成。     

Microwave Heating of Scrambled Eggs in a Hospital Foodservice System

Temperatures of scrambled eggs (117 portions) after heating in microwave ovens in a hospital foodservice system were examined to (a) determine the extent to which temperature could be controlled in actual foodservice operation and (b) the relationship of voltage, portion weight, temperature before heating, and power (W) within ovens to temperature of food after heating in actual operation. Temperature variability was controlled to the extent of 5°C (average 2 scoops), as indicated by the standard deviation, with 96% of the temperatures at 74°C or above as indicated by standard score conversion (2). Significant (P < 0.01) correlation (-) was found between temperature of eggs after heating and voltage; this occurred within a range of 3V. Temperature after heating was significantly (P < 0.01) correlated (+) with temperature before heating and (-) with portion weight (P < 0.05). No significant relationship was found between temperature and power (W) within ovens but voltage was significantly (P < 0.01) correlated (-) with power. Food may be heated in microwave ovens in foodservice systems if factors influencing heating are rigidly controlled, but complete safety cannot be assured.     

Nutrient Retention in Pork, Turkey Breast and Corned Beef Roasts after Infrared and Convective Heat Processing

Roasts were heat processed by infrared and convection to compare the effects of these alternate heating methods upon nutrient retention. In addition to proximate analyses, nutrients analyzed included: thiamin, riboflavin, seven fatty acids, 18 amino acids, ammonia, sodium, phosphorus and iron. Convective heating of turkey breast and corned beef produced a higher product yield. Few significant differences between heat processed samples were revealed. After convection heating of corned beef, riboflavin was significantly higher (P < 0.05) than after infrared heating. Similarly, arachidonic acid (C20:4) was higher in turkey breasts. After infrared heating of pork, aspartic acid, threonine, serine were lower than after convective heating; ammonia was higher.     

Effects of Hot Air-assisted Radio Frequency Heating on Quality and Shelf-life of Roasted Peanuts

Roasting is a critical step in processing peanut snack foods. The conventional roasting using hot air ovens has drawbacks of low production rate, poor product quality, and high energy cost. This study investigated the feasibility of using hot air-assisted radio frequency (RF) to roast dried salted peanuts. Physicochemical properties, volatile compounds, and sensory quality of the roasted peanuts were determined. The quality changes and shelf-life of vacuum-packaged roast peanuts stored under an accelerated shelf-life testing (ASLT) trial conducted at 20 and 50 °C were also evaluated. After 45 min roasting, moisture content of the salted peanuts reduced from initial 7.7 to 3.1 % and acid and peroxide values were 0.26?±?0.02 mg/g and 2.46?±?0.10 meq/kg, respectively, all in the levels associating with good quality of roasted peanuts. Sensory evaluation further validated the good quality of the roasted peanuts. Totally, 69 volatile compounds were identified in the roasted peanuts, in which 3 new volatiles were produced after about 13 weeks of storage. During the storage, relative concentrations of the favorable volatile compounds (mainly pyrazines and furan compounds) decreased in a certain degree, while the relative concentrations of some undesirable flavor compounds increased. The roasted peanuts had 31 weeks of shelf-life based on the industrial standard on the peroxide value. This study demonstrated that hot air-assisted RF roasting can produce high-quality roasted peanuts with prolonged shelf-life, thus, a new technology for the peanut roasting industry.     

Aggregation behaviour of bovine serum albumin as a cause of sauce liquid separation by heating

Heating white sauce with bovine serum albumin (BSA) at 90 °C caused the sauce to separate into aggregates and liquid phase, although this did not occur at 75 °C. Data from differential scanning calorimetry of BSA solution suggested that heat denaturation of BSA was insufficient at 75 °C but was complete at about 90 °C. Larger aggregates of BSA were formed by heating at 90 °C compared with 75 °C, as shown by gel permeation chromatography combined with a multi‐angle laser light‐scattering detector. Dynamic viscoelasticity measurement showed a higher storage modulus of BSA solution formed by heating at 90 °C than at 75 °C. Scanning electron microscopy revealed a random agglomerate structure of aggregates (spherical aggregates) obtained by 75 °C heating, while a well‐developed network structure containing voids was observed after heating at 90 °C. These findings suggest that sauce liquid separation induced by heating at 90 °C is due to encapsulation and restriction of white sauce components by large structured aggregates of BSA containing voids. Aggregates generated at 75 °C were not sufficiently developed and structured; therefore there was no sauce liquid separation due to encapsulation and restriction of components. © 2000 Society of Chemical Industry     

Shelf-life of infrared dry-roasted almonds

Infrared heating was recently used to develop a more efficient roasting technology than traditional hot air roasting. Therefore, in this study, we evaluated the shelf-life of almonds roasted with three different approaches, namely infrared (IR), sequential infrared and hot air (SIRHA) and regular hot air (HA). Nine medium roasted almond samples produced by the aforementioned heating methods were processed at three different temperatures (130, 140 and 150 °C), packed in paper bags and then stored at 37 °C for three, six or eight months. Shelf-life of the roasted almonds was determined by measuring the changes in colour, peroxide value, moisture content, water activity, volatile components and sensory quality. No significant difference was observed in moisture content and water activity among the almond samples processed with different roasting methods and stored under the same conditions. GC/MS analysis showed that aldehydes, alcohols, and pyrazines were the main volatile components of almonds. Aliphatic aldehydes such as hexanal, (E)-2-octenal, and nonanal were produced as off-odours during storage. Although the overall quality of roasted almonds produced with SIRHA and HA heating was similar during the first three months of storage, their peroxide value and concentration of aliphatic aldehydes differed significantly for different roasting methods and increased significantly in all roasted samples during storage. We postulate that hexanal and nonanal might be better indicators of the shelf life of roasted almonds than the current standard, peroxide value.     

Impact of Microwave-Assisted Heating on the pH Value,Color, and Flavor Compounds in Glucose-Ammonium Model System

The effect of microwave and oil bath heating on the evolution of Maillard reaction including pH, color and degree of glycation, and flavor compounds was investigated. Maillard reaction was induced by heating glucose-ammonium system for 10–30 min at 100–120 °C. Results indicated that microwave heating was more effective than traditional oil bath heating in Maillard reaction. The more decrease of pH values, higher A₄₂₀, lower whiteness and chroma, and stronger glycation were recorded in the model system heated by microwave. Moreover, microwave heating did not affect the contents of pyrazines extracted by dichloromethane but affect the formation of D-limonene extracted by ethyl acetate from model system. In addition, 2-hydroxy-3-methyl-2-cyclopentene-1-one, 3-methyl-2-pyrazinyl-methanol, and 6-methyl-2-pyrazinyl-methanol were firstly reported as flavor compounds in the glucose-ammonium system.     

The effect of roasting method on headspace composition of robusta coffee bean aroma

Robusta coffee beans were roasted by three methods, i.e. convectively at 230 °C, by microwaves at 700 W, and by the coupled convective–microwave (CMR) method (the simultaneous convective heating at 230 °C and microwaving at 700 W) for 590, 670, and 370 s, respectively. The ultimate temperature of roasted beans was 238, 207, and 228 °C, respectively. Volatile compounds were determined in the headspace by GC-SPME both in samples of roasted coffee and in green beans to find effects of roasting methods on their formation and retention. Eighty-two and 148 odorants were identified in green and roasted coffee, respectively. The highest contents of the latter were found in coffee roasted by the coupled method because both the relatively short time of roasting and moderately high final temperature of beans favored retention of volatile aroma compounds. Because of these reasons, the contents of odorants were the lowest in convectively roasted coffee.     

Cholesterol and Selected Attributes of Pork Tenderloin Steaks Heated by Conventional, Convection, and Microwave Ovens to Two Internal Endpoint Temperatures

Six treatment combinations for determination of cholesterol and selected quality attributes of pork tenderloin steaks were studied with three oven types (conventional, convection and microwave) and two internal endpoint temperatures (71°C and 77°C). In general, pork tenderloin steaks heated in the microwave oven had lower evaporative loss and higher drip loss. Cholesterol (wet weight basis) of the pork steaks was not affected by oven type; however, heating to the higher internal endpoint temperature (77°C) increased (concentrated) the cholesterol. On a dry weight basis, microwave-heated steaks contained more cholesterol when compared to conventional and convection-heated samples.     

Effects of Sodium Tripolyphosphate on Physical and Sensory Properties of Beef and Pork Roasts

Six paired beef round and pork loin roasts were used to determine the effects of sodium tripolyphosphate (STPP) on fresh and reheated roasts. Roasts were pumped 10% of their weight with distilled water (control) or with distilled water containing 4.75% STPP. Roasts were cooked to internal temperatures of 70°C (beef) or 75°C (pork) and evaluated after 0, 1 or 3 days (roasts were reheated to cooked temperatures). This study indicates that phosphate in pork and beef roasts allowed them to be reheated after 1 and 3 days of refrigeration with minimal losses of juiciness, tenderness or flavor intensity, Phosphate injection reduced warmed-over flavor in reheated pork roasts but was not successful in decreasing the incidence of warmedover flavors in reheated beef roasts.     

ENTEROTOXIN FORMATION IN FOODS BY CLOSTRIDIUM PERFRINGENS TYPE A

Growth, sporulation and enterotoxin formation in various foods inoculated with a Clostridium perfringens type A enterotoxin-producing strain were studied. Good vegetative growth, 10⁷–10⁸ cells/g, was obtained after 4 hr of anaerobic growth and remained almost the same throughout the 20–24 hr observation in most of the foods. A gradual increase in spore count to the level of 10⁴–10⁵/g was observed with an increase in the incubation time. Enterotoxin was detected in moist cooked chuck roast, ground beef and turkey as well as in moist cooked and dry roasted chicken at levels up to 0.125μg/g. The earliest time at which enterotoxin was detected was after 10 hr of anaerobic growth in moist cooked turkey at 37°C. Although growth and some sporulation occurred, enterotoxin was not detected in dry roasted beef or turkey with or without gravy, or in moist cooked pork or lamb. Poor growth and sporulation also were obtained with chicken broth, chicken gravy and beef gravy. In moist cooked turkey that had been temperature abused for 6 hr at 37°C, held cold for 15 hr and reheated to 37°C, toxin could be detected after only 5 hr of holding at 37°C. The ability of certain foods to support sporulation and enterotoxin formation indicates that such preformed enterotoxin may contribute to early onset of symptoms in some cases of C. perfringens food poisoning.     

Innovative Quality Improvement by Continuous Microwave Processing of a Faba Beans Pesto Sauce

Nowadays, consumers demand healthy, safe, and ready-to-eat horticultural products because of their lifestyle. In this regard, new legume-based food product development with eco-innovative technologies seems to be an interesting market. The effect on quality of an innovative pesto sauce, made of fresh faba bean seeds, of an alternative continuous microwave treatment pasteurization (MW, 11 kW; 30 s) regarding a conventional pasteurization (85 °C; 5 min) throughout 20 days at 5 °C was studied. Non-heated blended samples were used as control. The microbial quality was satisfactory in all treatments. MW treatment improved the sensorial quality of pesto sauce and decreased condensed tannins. Additionally, MW-treated samples showed the best texture, consistency, and color, preserving its chlorophyll and carotenoid content. On the other hand, thermal treatments showed a decrease in total phenolic compounds (TPC) and antioxidant capacity (TEAC) after heating, regarding control samples; however, TPC and TEAC remained quite constant throughout the storage.     

Effect of Warmed-Over Flavor on Consumer Acceptance and Purchase of Precooked Top Round Steaks

Retail samples of semimembranosus were roasted, sliced, wrapped in aluminum foil and stored at 1.0°C for 0, 1, 4, and 7 days. A panel of 100 consumers evaluated samples for the variables: preference, purchase intention, flavor, off-flavor, and intended purchase frequency at three price levels. Panelists did not rate the 0, 1, and 4-day samples differently on all sensory variables, but the 7-day sample was rated as significantly different (P < 0.05) from all samples on each sensory variable. Results indicate that consumers were unable to detect off-flavor in reheated semimembranosus samples at TBA numbers of 6.3 or lower.