EFFECTS OF COOKING AND SUBSEQUENT REHEATING ON THE PROPERTIES OF LOW-FAT BEEF PATTIES

Low-fat (10%) beef patties manufactured with 0.5% iota carrageenan, were subjected to one-time cooking from the raw to fully cooked state or precooking and later reheating before evaluating sensory, shear force and cooking properties. The samples were reheated in a convection oven or in a simultaneous top and bottom contact grill set either at 121 or 191C. Precooking followed by reheating produced only slight changes in sensory properties (reduced tenderness, increased juiciness and increased beef flavor). Convection oven cooking improved tenderness only for one-time cooked patties. With the double contact grilling system, the 121C surface temperature enhanced tenderness (sensory and shear force) and cooking yields of precooked-reheated patties. Low-fat beef patties formulated with iota carrageenan appear capable of being subjected to a variety of cooking approaches and temperatures without major changes in cooked patty properties.     

FERMENTED COWPEA FLOUR: PRODUCTION AND CHARACTERIZATION OF SELECTED PHYSICO-CHEMICAL PROPERTIES

A simplified solid-substrate fermentation and milling process for preparing flour from nondecorticated cowpeas (cv. White Acre) was developed. Yield of fermented flours compared to starting substrate was about 73%. Total solids loss (ca. 21–23%) was due to soaking (6%), boiling (11%), fermentation (2–4%) and grinding (2%). Moisture loss during drying was approximately 5%. The pH of fermented flours ranged from 6.4 to 6.9. Fermented flours had less packed density but greater unpacked density than the control flour. About 41–44% of flour particles passed through a 0.297-mm sieve; 65–72% of these particles were in the exclusion range of 0.037–0.074 mm. An increase in color saturation of fermented flours was due mainly to increased b* (yellowness) values. Fermented flours contained about 28% protein, 1.8–2.0% fat, 4.9–6.2% moisture, 2.7% ash, and 61–63% total carbohydrate.     

PHYSICAL AND SENSORY CHARACTERISTICS OF LOW-FAT ITALIAN SAUSAGE PREPARED WITH HYDRATED OAT

Low‐fat Italian sausage was prepared with hydrated oat flakes at 10, 20 and 30% (w/w), and precook times of 0, 2 and 4 min. Cook loss and expressible moisture, cutting force and texture profile analysis, color and consumer sensory analysis were analyzed by response‐surface methodology. Minimum cook loss occurred at 16.3% of the hydrated oat and 0.76 min precook time, while expressible moisture decreased with increasing oat levels and decreasing precook time. In general, both cutting force and hardness decreased with hydrated oat level. Measurements of L*, a* and b* showed a slightly lighter product and a shift to more red and yellow cooked product at intermediate oat levels and precook times. For sensory attributes, both oat level and precook time were significant. Greatest flavor and texture likeability were attained with hydrated oat levels of 3–12%, and precook times of 1.5–3 min. Greatest overall likeability occurred over a region of 0–14% hydrated oat, and 1.1–3.3 min precook time.     

PATTY FORMATION METHOD, THICKNESS AND WEIGHT EFFECTS ON PROPERTIES OF COOKED LOW-FAT BEEF PATTIES

Effects of patty thickness (0.95 and 1.27 cm), weight (90 and 113 g) and type of patty fill method (traditional gravity fill = FF and twisted through holes into mold = TF) were evaluated using low-fat (10%) ground beef. An increase in patty thickness from 0.95 cm to 1.27 cm, resulted in a decreased (P<0.01) sensory firmness and peak load (Newtons) and increased (P<0.01) initial juiciness. TF fill method and 1.27 cm thick FF treatments improved tenderness and juiciness over 0.95 cm thick FF patties. This study revealed that improvements in tenderness and juiciness of low-fat beef patties can be attained through use of appropriate patty formation procedures.     

EFFECT OF ACETIC ACID AND CMC ON RHEOLOGICAL AND BAKING PROPERTIES OF FLOUR

The effects of addition of acetic acid (0.05, 0.1, 0.2 and 0.4%) and carboxymethyl cellulose (0.25, 0.5, 1.0, 2.0%) on rheological, gas release and bread making properties of flour were examined. Water absorption, dough stability, dough development time, loaf volume and overall acceptability scores decreased, while degree of softening and bread firmness increased with an increase in acetic acid concentration. Addition of CMC showed similar effects on dough stability, dough development time and degree of softening. Maximum dough height (H_m), maximum height of CO₂ production (H,_m), gas formation and retention decreased with the increase in acetic acid and CMC levels. Addition of 0.05% of acetic acid in combination with 0.25% CMC was most effective in improving dough characteristics, and overall acceptability scores.     

ACCEPTABILITY OF VARIOUS GROUND BEEF AND PORK PRODUCTS EXTENDED WITH MECHANICALLY SEPARATED BEEF

Six blends of ground beef and six blends of ground pork containing 0, 15, 30, 45, 60 or 75% mechanically separated beef (MSB) were prepared. Also five batches of fermented sausage and spiced luncheon loaf containing 0, 5, 10, 15 and 20% MSB were formulated. Level of MSB was not related to juiciness rating or mealiness scores of cooked beef/MSB or pork/MSB patties. The level of MSB significantly affected overall eating satisfaction ratings for each blend of MSB patties. MSB at levels of 15% or more had a negative effect on flavor acceptability of cooked ground beef or pork. Fermented sausage products could be extended with only 5% MSB without creating defects in visual appearance or sensory properties. However, the inclusion of 20% MSB yielded a spiced luncheon loaf which was higher in eating quality than an all-beef control. The beef/MSB patties, fermented sausage, and spiced luncheon loaves containing 15% MSB were acceptable for visual appearance. Based on this study, MSB produced from a press type machine, can be blended up to 15% with ground beef, ground pork and sausage products without significantly decreasing raw appearance, sensory properties or storage life. Since MSB is a red meat product available at a similar low cost as textured vegetable protein, the red meat industry would benefit from expanded use of this high protein extender.     

CHARACTERISTICS OF LOW-FAT FRANKFURTERS MANUFACTURED WITH MODIFIED BEEF CONNECTIVE TISSUE

A 3 fat level (8%, 16% and 24%, finished weight basis) × 5 modified connective tissue level (0%, 10%, 20%, 30% and 40%, meat block basis) complete factorial design was employed to characterize frankfurters manufactured with modified beef connective tissue (MCT). Thermal processing yields improved 2–3% with the addition of 20% or more MCT. Level of MCT did not affect average consumer cook yields. Kramer Shear parameters were higher with higher levels of MCT. Frankfurter cohesiveness declined with an increase in MCT. A consumer panel found low-fat frankfurters to be less desirable in almost all traits than high fat products. Frankfurters with 10–20% MCT were as desirable as controls (0% MCT). Frankfurter external and internal color was lighter as level of MCT increased. Frankfurters with MCT were rated as desirable by a consumer sensory panel, and had color and yields similar to higher fat products.     

MICROBIAL AND SENSORY CHARACTERISTICS OF A FERMENTED SAUSAGE EXTENDED WITH CARBOHYDRATE MATERIALS

Microbial and sensory properties of a fermented sausage, substituted 24% w/w with gelatinized corn starch were studied. The results showed no significant differences in lactic acid bacteria populations between extended samples and the controls, but higher counts of Brochothrix thermosphacta and pseudomonas in extended samples. Results did not indicate any significant differences in odor and flavor, but a difference in texture. A sensory profile diagram of both treatments was obtained, showing the main sensory notes of the products. From the sensory analysis, it was concluded that starch addition up to the levels applied only alter the texture.     

PHYSICOCHEMICAL CHARACTERISTICS OF FERMENTED SAUSAGE EXTENDED WITH CARBOHYDRATE MATERIALS

To reduce the production cost of fermented sausage, extension with a cheaper material was studied. Variables studied were pH, water activity, acidity, texture, color and volatile production. Starches added with gums (carrageenan and agar) produced abundant syneresis during storage whereas those made from amylopec-tin (Maicena^TM) and waxy corn (Firmtex^TM) were more stable. Syneresis was produced when pH decreased during fermentation from > 6.0 to 4.2–4.4. Sausages added with Firmtex^TMwere tougher, as expressed by less displacement of a PAM penetrometer probe. Sausages substituted with 24% Maicena^TM, when compared to a control, had significant differences with respect to pH, water activity, and color: L-values and a-values, but not in production of volatile compounds (diamines and free fatty acids) related to flavor and aroma. Therefore, it can be expected that, with the exception of texture, other characteristics of fermented sausages are not altered when extended with amylopectin starch.     

PHYSICAL, CHEMICAL, AND SHELF-LIFE CHARACTERISTICS OF LOW-FAT GROUND BEEF PATTIES FORMULATED WITH WAXY HULL-LESS BARLEY

Ten percent hydrated, cracked waxy hull-less barley was incorporated into 90/10 (percentage lean/percentage fat) ground beef to produce a low-fat beef-barley patty which had substantially higher cook yields and water retention than either of the controls (80/20 beef, 90/10 beef). Instron texture profile analysis revealed that the beef-barley burger was less chewy, springy, cohesive, gummy, and hard than the controls. Aerobic plate counts indicated that, after six days of refrigerated storage, the beef-barley patty did not spoil any faster than the control. Thiobarbituric acid numbers (an indication of lipid oxidation) suggested that waxy barley incorporated into ground beef may have an antioxidant effect when patties are stored frozen for more than 90 days.     

INFLUENCE OF NATIVE LIPIDS ON THE RHEOLOGICAL PROPERTIES OF WHEAT FLOUR DOUGH AND GLUTEN

We report on the viscoelastic properties of dough and gluten (prepared by ultracentrifugation) after the flour lipids had been removed by solvents differing in polarity (chloroform, ethanol and diethylether). The extracted lipids were fractionated by thin layer chromatography. The flours differed in lipid composition after the extraction. Ethanol removed more polar lipids than the other solvents. Removal of lipids (0.6–0.9% on flour weight) altered the viscoelastic properties of dough significantly, whereas those of gluten were only marginally affected. The storage modulus (G′) of dough increased with used solvent polarity. The highest value of G′ was observed for the dough made with the flour where the lipids were removed by ethanol. This was consistent with a marked decrease in the frequency dependence of G′ of dough when the lipids were removed.     

RHEOLOGICAL BEHAVIOUR OF THREE BIOPOLYMER/WATER SYSTEMS, WITH EMPHASIS ON YIELD STRESS AND VISCOELASTIC PROPERTIES

Flow and viscoelastic properties of three thickened systems are presented: aqueous solutions of locust bean gum, of xanthan and a dispersion of a crosslinked waxy corn starch. Creep measurements allow investigations at very low shear rates. The existence of a yield stress is discussed. Flow was observed at low shear rates, but the starch paste exhibited pseudo-yield stress behaviour. Dynamic measurements were performed and the relationships between flow curves and mechanical spectra are discussed.     

VISCOELASTIC PROPERTIES OF WHEAT FLOUR DOUGHS: VARIATION OF DYNAMIC MODULI WITH WATER AND PROTEIN CONTENT1

The elastic and loss moduli of fiue types of wheat flour doughs were measured in an eccentric rotating disc (ERD) rheometer. G’ and G”, determined from the linear portions of the response curve, were very sensitive to water content, decreasing as water content increased. Differentiation among samples was greatest at the highest water content. Results also depended on protein level, with higher moduli being observed at higher protein level. Samples mixed in a Farino-graph to constant consistency showed differing values of both storage and loss moduli. The ERD geometry thus appears suited to characterization of doughs and to study of component interactions in such systems.     

EFFECT OF MINERAL FORTIFICATION ON RHEOLOGICAL PROPERTIES OF WHOLE WHEAT FLOUR

This study was aimed to evaluate the rheological changes that take place in the dough as a result of addition of elemental iron, ferric sodium ethylenediaminetetraacetate, zinc sulphate and zinc oxide in various combinations to whole wheat flour (WWF), packaged in polypropylene woven bags and tin boxes and stored for a period of 60 days under ambient and controlled conditions of temperature and relative humidity. Water absorption (WA) capacity, dough development time (DDT) and dough stability time (DS) of the fortified WWF were measured by farinographic method, and peak viscosity was assessed by viscographic analyses. WA capacity and DDT of flours increased during storage. Fortification significantly (P  <  0.05) affected WA, DDT, DS and viscographic characteristics of the flours. Packaging materials (P  <  0.05) influenced WA, DDT and DS, while storage condition had only affected viscographic properties of the flours.

PRACTICAL APPLICATIONS

The success of any fortification program depends on the stability of micronutrients and food to which they are added. Exposure of the fortificants to any of the physical and chemical factors including heat, moisture, air, or light and acid or alkaline environments during food processing, packaging, distribution or storage affects their stability. The rheological properties of dough made from fortified flours determine the quality of the fortified end product. Changes in rheological properties as a result of the incorporation of fortificants in the flour, its storage under variable conditions and length of time might have an effect on quality, cost and nutrition of the product.