MICROWAVE BLANCHING EFFECTS ON COLOR, CHEMICAL AND SENSORY CHARACTERISTICS OF FROZEN ASPARAGUS

Asparagus was blanched for 4 min using: conventional boiling water (BW), steam (ST), microwave (MW), or microwave heated in boilable bags (MWB). Samples were ice-cooled, bagged, heat-sealed and stored at ?18C for 4 weeks. Peroxidase activity was reduced from 98–114 units in fresh, unblanched to 1–7 units in blanched asparagus. Reduced ascorbic acid (RAA) content in fresh, unblanched asparagus was ～49 mg/100 g; RAA content in fresh, BW-blanched asparagus was ～44 mg/100 g. Frozen, unblanched asparagus retained about 40% of original RAA content; BW-blanched asparagus retained 61%, and MWB-blanched asparagus retained 87%. After frozen storage all samples were darker than freshly blanched samples. Blanching increased and freezing decreased greenness of all samples. Blanching increased yellowness of fresh samples; after frozen storage, blanching treatment differences were lost. Unblanched samples had the highest appearance scores; unblanched and MW-blanched samples had the highest color scores. Overall quality of the microwave blanched asparagus was as good as or superior to conventionally blanched asparagus.     

MICROWAVE BLANCHING EFFECTS ON CHEMICAL, SENSORY AND COLOR CHARACTERISTICS OF FROZEN GREEN BEANS

Green beans (cv. Mustang) obtained from the University of Illinois at Urbana-Campaign Horticulture plots were assayed within 3 h of harvest. Beans were blanched in covered containers: conventional boiling water (1900 ml, 3 min) (BW), steam (300 ml water, 3 min) (ST), microwave heated in 1 L glass containers (60 ml water, 3 or 5 min, 700 W) (MW-3, MW-5), and microwave heated in 1 L Seal-a-Meal^TM bags (45 ml water, 3 min) (MW-Bag). Baseline data were collected immediately after blanching. Aliquots were frozen at – 18C for 4 weeks. Unblanched beans had 82 units of peroxidase activity/min; activity was zero immediately after all blanching treatments. Reduced ascorbic acid (RAA) content was highest for unblanched, ST and MW-5 beans and lowest for BW and MW-Bag beans immediately after blanching. ST beans retained 100% of original RAA. Instron shear force (kg) was highest for unblanched beans and lowest for BW and MW-Bag beans immediately after blanching. After frozen storage, ST and BW beans had the lowest shear values. Visual color was poorest for MW-5; other treatments were not different. Microwave blanching green beans for 3 min in a covered container or bag prior to 4 weeks frozen storage resulted in a product that was not different in RAA content, retention or color from BW blanched beans; however, these samples differed in tenderness and crispness from boiling water blanched beans.     

CHEMICAL, NUTRITIVE AND SENSORY CHARACTERISTICS OF TOMATOES BEFORE AND AFTER CONVENTIONAL AND MICROWAVE BLANCHING AND DURING FROZEN STORAGE

The objective of this study was to evaluate the effects of microwave blanching on chemical, physical and sensory characteristics of tomatoes prior to and after frozen storage. Tomatoes were blanched (4 min) using four treatments: conventional boiling water (BW), steam (ST), microwaved in a glass container (MW), and microwaved in boilable bags (MWB). The lowest moisture content occurred in MW‐blanched tomatoes before (92%) and after (86%) frozen storage. These tomatoes had the highest reduced ascorbic acid (RAA) content and the highest RAA retention (> 23 mg/100 g, >91%) after blanching and after frozen storage. After blanching, MWB‐blanched tomatoes were the lightest, while after frozen storage, ST‐blanched tomatoes were the lightest. BW‐blanched tomatoes had generally higher flavor, texture and appearance scores. This study demonstrated that though visual color and sensory attributes were highest for BW‐blanched tomatoes, MW‐blanched tomatoes retained more nutritive value in the finished product.     

EFFECTS OF BLANCHING METHOD ON THE QUALITY CHARACTERISTICS OF FROZEN PEAS

This study evaluated the effects of microwave blanching prior to freezing as an alternative pretreatment for frozen peas. Peas were blanched (steam‐, boiling water immersion‐, microwave‐ or microwave‐blanched in a bag), frozen and evaluated after 0, 6 and 12 weeks for moisture and ascorbic acid content, peroxidase activity, visual appearance and instrumental color, and after 6 and 12 weeks for aroma, flavor and texture. All blanch treatments reduced peroxidase activity by 97% compared with controls (unblanched); blanching methods did not differ. Steam blanching resulted in significantly better ascorbic acid retention than all other treatments; microwave blanch treatments were either equivalent to or better than boiling water immersion. Both microwave treatments darkened (L* value) peas. Microwave‐blanched peas were visually greener than other treatments, but their appearance was less intact. Aroma and flavor were similar among blanch treatments. Texture of boiling water immersed peas was similar to the two microwave treatments.     

EFFECTS OF COLOR AND SWEETENERS ON THE SENSORY CHARACTERISTICS OF SOFT DRINKS

College age panelists, 129 in number, evaluated an artificially cherry flavored soft drink which varied in color level, sweetener level and sweetener type, for overall liking, sweetness, color, flavor, tartness, and aftertaste intensity. Three two-factor, second order central composite designs were developed which contained either sucrose, aspartame, or aspartame acesulfame-K in a 60:40 ratio as the sweetener. Each design yielded nine drinks which had five color levels and five orthogonal sweetener levels centered around a commercial sample. Mean panel reponses for each sensory characteristic were subjected to regression modeling, producing a regression equation and a three dimensional prediction surface. Response patterns were then compared both within, and between sweetener types. Sensory responses were sensitive to manipulations of the two independent variables, color and sweetener. Increasing levels of sweetener increased sensory ratings for overall liking, sweetness, flavor and aftertaste, and decreased ratings for tartness. These effects were similar across sweetener types. Non significant effects of color were seen only on flavor, tartness, and aftertaste intensity, and were not found for all sweeteners.     

冻藏时间对速冻水饺品质影响的试验研究

主要考查冷冻保藏时间对于速冻水饺的理化性质、微生物指标及感官性状的影响。结果表明,随保藏时间延长,饺皮的水分含量呈线性规律下降,从最初的（37．25±0．44）％降至试验末期的（32．5±0．92）％。而对于样品的酸价,随保藏时间延长,酸价升高,从初始的（2．01±0．01）mg KOH／g升至试验末期的（2．38±0．02）mgKOH／g。菌落总数及嗜冷菌菌落总数结果相似,都随保藏时间延长而增加,菌落总数从（1．27±0．09）×10^5 cfu／g升至（3．26±0．08）×10^5 cfu／g,而嗜冷菌菌落总数从（2．44±0．06）×10^5 cfu／g升至（3．73±0．15）×10^5 cfu／g。结合对水饺饺皮和饺馅的感官评价表明,速冻水饺的食用品质随保藏时间呈下降趋势,相对来讲,保藏时间越短,样品的食用品质越好。     

EFFECTS OF ENZYME APPLICATIONS ON SENSORY, CHEMICAL AND PROCESSING CHARACTERISTICS OF BEEF STEAKS AND ROASTS

Semitendinosus steaks were injected, dipped or tumbled to contain 50 or 100 ppm bromelin (B) or papain (P), frozen, cut into steaks and cooked. Cooked, P-treated steaks had more mushy texture, more intense off-flavor and more bound water than B-treated steaks. Steaks treated with 100 ppm enzyme were more mushy and contained more bound water in the raw state, but not in the cooked state, than those with 50 ppm. Halved ST roasts were injected or tumbled with 10 or 20 ppm B, or 2.5 or 5 ppm P, precooked, refrigerated and reheated. Injected roasts lost more weight during cooking and were more mushy and contained less connective tissue than those which were tumbled.     

ALPHA-TOCOPHEROL EFFECTS ON COLOR AND SENSORY CHARACTERISTICS OF GROUND PORK DURING RETAIL DISPLAY

To assess the effects of a-tocopherol addition on lipid and pigment oxidation of ground pork, 10, 100 or 1000 ppm was added directly to ground pork in a food grade carrier (2% Medium Chain Triglyceride Oil) then pork was overwrapped with polyvinyl-chloride film and displayed at 4C for three days. Addition of α-tocopherol to ground pork had limited effects on color and sensory characteristics. Display time and light present during display had detrimental effects on a* value, total color, red color contributed by oxymyoglobin, percent of myoglobin, metmyoglobin and oxymyoglobin, visual red and grey colors.     

EFFECTS OF CULTIVARS, BLANCHING TECHNIQUES, AND COOKING METHODS ON QUALITY OF FROZEN GREEN BEANS AS MEASURED BY PHYSICAL AND SENSORY ATTRIBUTES

Effects of cultivars, blanching techniques, and cooking methods on the color, texture, and sensory characteristics of frozen green beans were investigated. Provider beans were firmer than the Contender cultivar following frozen storage and cooking when evaluated instrumentally and by a sensory panel. Microwave-blanched beans were harder according to Instron measurements, and sensory scores for firmness and toughness were higher than beans blanched by boiling water or steam. Green beans blanched or cooked by microwaves had grassy aromas and strong off-flavors that were not detected in those blanched or cooked by conventional methods. Microwave cooked beans were greener and firmer than those conventionally cooked.     

ENHANCEMENT SOLUTION EFFECTS ON SHELF-LIFE, COLOR AND SENSORY CHARACTERISTICS OF PORK CHOPS DURING RETAIL DISPLAY

Abstract The objective of this study was to evaluate shelf-life, color and sensory characteristics of pork chops from loin sections (n = 12/treatment) injected (110% original weight) with a potassium lactate/potassium acetate solution (2 %) + phosphate (0.35%)/salt (0.35%), compared with those injected with sodium lactate (3%) + phosphate/salt, or phosphate/salt alone, to control loins. After 96 h of display, aerobic plate counts (CFU/cm²) were significantly lower (P<0.05) for chops enhanced with the lactate + acetate combination than for the other treatments. Hue angle (tan^-1 b*/a*) of lactate + acetate enhanced chops was lower (P<0.05) than all other treatments at 96 h indicating that red color did not deteriorate as rapidly as in control, phosphate + salt- and lactate-injected chops. Sensory data suggest that lactate + acetate and lactate-injected chops were juicier, more tender, and less bitter than the noninjected chops. A difference in enhancement solution retention may partially explain differences in plate counts and sensory characteristics.     

EFFECTS OF BLANCHING, CHEMICAL TREATMENTS AND FREEZING METHODS ON QUALITY OF FREEZE-DRIED MUSHROOMS

SUMMARY –Mushrooms, Agaricus bisporus, were cut into slices about 5 mm thick. The polyphenoloxidase activity in the sliced mushrooms was inhibited by: (a) dipping in sodium metabisulfite solution containing 200 ppm SO₂; (b) dipping in 2% NaCl solution; and (c) blanching in boiling water for 2 min followed by evaporative cooling. The products were frozen with Freon-12 at –22°F for 60 sec. The frozen mushrooms were dried to 3% moisture in a Stokes freeze drier and sealed under vacuum in No. 2–1/2 cans. The freeze-dried product made by the Freon-dipping process was better in quality and firmer in texture than that made by the slow-freezing process. Blanching the fresh mushrooms in boiling water for 2 min prior to freezing results in a lighter color in the freeze-dried products after rehydration. However, the product was less attractive in flavor and texture. The blanching process caused considerable loss of water-soluble solids and ascorbic acid. The effects of processing variables on the chemical, physical and organoleptic quality of the rehydrated products are presented.     

A RESEARCH NOTE CHEMICAL, PHYSICAL, AND SENSORY CHARACTERISTICS OF COLOR MODIFIED PORK RESTRUCTURED CHOPS

Restructured pork chops were manufactured from the lean tissue of dressed sows that were color modified(CM) with a potassium buffer rinse to attain lighter appearance. This product was compared with counterpart samples that were not color modified(C). Measurements included CIE L*, a*, b* values, visual traits, sensory traits, shear force, pH, and percentage of moisture, fat, protein, protein solubility, and cooking loss. The CM samples were lighter colored (P<0.05), exhibited less (P<0.05) flavor intensity, had a higher (P<0.05) pH, and sustained less (P<0.05) cooking loss. No differences (P>0.05) between the CM and C samples were found in juiciness, tenderness, Warner-Bratzler shear force, and soluble protein. The CM samples exhibited less protein content and lower Lee-Kramer shear force values. Results confirm that sow meat can be lightened without adversely affecting functional properties and taste attributes of restructured pork chops.     

SENSORY, COLOR, AND COMPOSITION CHARACTERISTICS OF YOUNG AND MATURE CHEVALINE

Data concerning the sensory attributes of chevaline, although limited, are of interest particularly to markets where it is sold as a human food. Thus, this study was conducted to characterize the sensory attributes of steaks from chevaline longissimus muscle from both younger (2–4 years of age: N = 10) and older animals (4 years and older: N = 10). Uncooked steaks (2.5 cm thick) were evaluated for moisture, fat, and protein content as well as color, instrumentally (L*, a*, and b*) and visually (lightness, redness, and brownness). Steaks were cooked to 70C (internal temperature) and then served to a sensory panel and evaluated by Warner-Bratzler shear. No differences (P < 0.05) were observed between age groups for sensory or color characteristics. Steaks from young animals had lower (P < 0.05) shear force values and protein content. Results suggest that age has limited effects on the composition, sensory, and color characteristics of chevaline steaks.     

CHEMICAL,MICROBIAL, AND SENSORY EVALUATION OF A FROZEN KUBBEE PRODUCT1

Kubbee, a Middle Eastern entree, was made from ground beef (10% fat), bulgur wheat, and spices with a filling of barbecue sauce. Shelf‐life of raw and precooked vacuum packaged product was evaluated during 180 days of storage at ?18C. Precooked frozen kubbees were reheated in a conventional or microwave oven, and uncooked frozen kubbee was baked in a conventional oven prior to evaluation. Except for redness, color values did not change during storage (P < 0.05), but pH and TBA values increased slightly after 60 days. Kubbee was microbiologically stable throughout the storage period. Some sensory properties of the products deteriorated with storage time and microwave reheating. Overall liking of kubbee by consumers was 7.2 on a scale of 1 to 9.     

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.     

EFFECTS OF MODIFIED ATMOSPHERE PACKAGING AND FILM ON SENSORY AND STORAGE PROPERTIES OF FROZEN HAM STRIPS

The effectiveness of modified atmosphere packaging and barrier properties of films upon the product attributes of frozen (IQF) ham strips, that are normally found at salad bars, was studied every 28 days over a period of 196 days. Three gases/mixture were used (CO₂, N₂ and ambient air) for flushing two pouches, one made from normal barrier film (861) and the other from a high barrier film (863). A triangle test and sensory evaluations were performed by a semi-trained panel (six members) for the following traits: freshness, structure, mouth feel, overall evaluation, aroma, appearance and off-flavors. Overall evaluation scores were acceptable up to 140 days of storage, regardless of the pouch used, but from 140 to 196 days, the product would be only marginally acceptable. Ham strips stored in N₂ or CO₂ atmospheres had a higher acceptance level than those stored frozen in ambient air. Panelists distinquished between fresh and stored product more frequently (75%) when the product was stored in ambient air pouches rather than CO₂ or N₂ atmospheres. Pouches made from the higher barrier film had lower (398/g) total aerobic plate counts than pouches (736/g) made from normal barrier film, but these counts are low and would be acceptable in industry.     

TOCOPHEROL EFFECTS ON FROZEN GROUND PORK COLOR

To assess the effects of α-tocopherol addition on lipid and pigment oxidation of ground pork, 10, 100 or 1000 ppm was added directly in a food grade carrier (2% medium chain triglyceride oil) then pork was overwrapped with polyvinyl-chloride (PVC) film and frozen (-34C) for seven months. Storage time increased extracted deoxymyoglobin percentage, metmyoglobin percentage determined by reflectance spectrophotometry, TBARS, hue angle, and pH, and decreased extracted oxymyoglobin percentage, L*, a* and b* values, and instrumental red color (% reflectance at 630 nm - % reflectance at 580 nm). Extracted metmyoglobin percentage increased through 140 days then decreased through 196 days. Alpha tocopherol increased deoxymyoglobin and decreased oxymyoglobin (extracted) expressed as a percentage of the total pigment, when compared with control samples. Metmyoglobin percentage (reflectance was highest in 10 ppm samples and lowest in 1000 ppm samples. Hue angle and total color were best correlated with other measures of red color.