大豆浓缩蛋白的运用

Characteristics of

Restructured Meat Products

Arthur De Anna, Matthew Hobbs, Kelly Jamieson, and Kapo Leung Governor’s School for Agriculture, Virginia Tech, Blacksburg, VA

24061

Table of Contents

Abstract………………………………………………………….3

Introduction……………………………………………………..4

Materials and Methods………………………………………..6

Results…………………………………………………………..9

References…………………………………………………….12

Effects of Soy Protein Concentrate on the Quality Characteristics of Restructured Meat Products

Arthur De Anna, Matthew Hobbs, Kelly Jamieson, Kapo Leung Governor’s School for Agriculture, Virginia Tech, Blacksburg, VA 24061

Abstract

Soy protein concentrate is a nutritious additive used to increase protein and add value to processed meat products. Soy protein concentrate was added to

restructured beef, pork, and lamb delicatessen rolls. Restructured products have been proven to be profitable and well accepted. Instrumental determination was completed on each treatment to measure cooked color, protein bind, and

moisture loss. A consumer sensory panel was conducted to assess treatment differences. Pork and soy protein concentrate recorded the only difference (p<0.05) in protein bind. No other differences (p>0.05) were seen between treatments for instrumental measurements and consumer evaluation.

Introduction

Further processed meat products are increasing in consumption. From the

1980’s to the year 2001 the consumption of meat began to decline, but as of the 1990s, the past ten years has remained at an average of 63.3 pounds per capita. In 2001 alone, each American consumed 9.2 pounds of processed beef. Per capita consumption of red meat, poultry and fish in 2001 was 211.1 pounds. According to statistics for the Supermarket Business Magazine, consumer

purchasing from grocery deli sales has increased from 9.5 million in 1988, to 24.4 million in 1999 (American Meat Institute, 2003). This significant growth in

consumption of processed meat was the result of new convenient, brand name products with added value (Sams, 2002). Improved nutritional value, better

portion control, and a larger variety of products influenced this continued growth.

To provide a high quality product at an inexpensive price, binders and extenders are utilized (Pearson and Gillett, 1996). Binders and extenders are additives that increase the yield and quality of products. General binders of processed meats consist of salt, phosphate, water and soy protein concentrate. Binders and extenders strengthen the protein bind, which improves water retention, texture, and yield of a product.

Salt serves several purposes. When included in a product, it is capable of absorbing moisture, improving product weight. Increasing the water holding capacity of the meat slat is capable of improving the natural flavor of the meat. Another main importance is to solubilize the myosin and actin proteins (Pearson and Gillett, 1996). Processed meat requires the extraction of muscle protein (or myosin). Extracting these proteins from meat allows products to bind well and give a firm texture. Another function of salt includes retardation of bacteria.

Phosphate is only allowed at a level of 0.5% in the finished product in the United States (Pearson and Gillett, 1996). Phosphate is used as an ingredient in restructured meat due to its ability to increase the emulsification of myofibrillar proteins. Purge loss is also decreased with the addition of phosphate (Pearson and Gillett, 1996). Several disadvantages of over using phosphate include;

soapy flavor, decrease in color development, and rubbery texture (Pearson and Gillett, 1996). Phosphate combined with salt and water, greatly increases water tension. Alkaline polyphosphates increase the water binding and fat emulsifying capacity of the myofibrillar proteins by increasing the pH level (Pearson and Gillett, 1996). The alkaline phosphate, salt combination improves meat-product juiciness while impairing firmness, particularly in low-fat products (Juttelstad, 1998). In addition, phosphates improve product shelf life by acting as an antioxidant for post-processed foods (Juttelstad, 1998).

Soy protein concentrate is very useful in improving flavor, protein content, cooking yield, and water binding in most meat products (Sams, 2001). Soy protein’s purpose as an extender is to increase water and fat binding (Pearson and Gillett, 1996). There are three types of soy; soy flour, soy protein

concentrate, and soy protein isolate (Pearson and Gillett, 1996). Soy protein concentrate was used rather than soy flour or soy protein isolate due to its special gelling properties that aid in binding chunked and formed meats better (Pearson and Gillett, 1996).

The addition of water to the meat is to increase water absorption and improve tenderness. It helps to dissolve the sodium chloride in order to give better distribution. Water also impacts upon the texture and tenderness of the restructured meat (Pearson and Gillett, 1996).

Appealing color and good flavor are the two main influences on consumer

purchasing of meat products (Kropf, 1980). Improvement of color and flavor in lower quality meat requires increased protein functionality through the use of

binders (Sams, 2001). Improvements in meat quality, ingredients and technology have allowed processors to produce a vast array of products, many that are undetectable from their natural cousins (Juttelstad, 1998). Texture and stability are crucial components of processed meat products. However, making a processed meat product that has consistent weight, and appealing color and flavor requires the addition of ingredients.

Tumbling is used to marinate and tenderize boneless meat cuts for restructured products. Tumbling allows the juices to be absorbed into the meat faster as well as to marinade the ingredients into the meat so the meat does not become

“mushy” (McEvoy, 2003). The action of tumbling not only aids in better extraction of the meat proteins, but also improves the speed of curing by increasing

absorption (Pearson and Gillett, 1996). Increased mixing time allows a greater surface area and more proficient breakdown of the structure of the muscle cells. Researchers concluded that the breakdown of cell walls releases more free water (Lawrie, 1988). This tumbling also breaks down the muscle structure with increased water-holding capacity and tenderness (Lawrie, 1988).

Materials and Methods

Processing

Raw materials utilized in this research were collected from the Virginia Tech Meats Laboratory. Samples were trimmed of external fat and bone and cut into 2.5 cm by 2.5 cm cubes. Several samples were combined for 3.162 kg

treatments. A marinade solution of 22% water on a meat weight basis (MWB), 0.5% phosphate on a finished product basis (FPB), and 2.0% salt on a finished product basis (FPB) was utilized in the marinade. Soy protein concentrate was dissolved in the brine for respective treatments. Each treatment was individually placed in a 20-liter tumbler (Model Inject Star MC 20/40/60/80-226, Globus, Austria). The marinade was evenly distributed inside the tumbler for respective treatments.

Following marinade formulation, the respective marinade was uniformly poured onto each sample. A vacuum pump removed the air inside the tumbler.

Treatments tumbled in the 4°C cooler for increased marinade absorption. The tumbler completed 20 revolutions per minute for 1.5 hours, stopping every 15 minutes for 10 minutes to increase brine absorption. When tumbling completed, each treatment was then manually stuffed into a 4.5 diameter fibrous casing and sealed with a mechanical Tipper Tie. When all treatments were completed they were stored in a 4°C meat cooler for 8 to 12 hours.

The restructured treatments were then cooked using an Alkar smokehouse (Model 1000, Alkar, Lodi, WI). The smokehouse schedule was 0.5 hours at dry bulb 54˚C and no wet bulb, 2 hours at dry bulb 66˚C and wet bulb 47˚C, 1 hour at dry bulb 77˚C and wet bulb 59˚C, and approximately 2 hours at dry bulb 85˚C and wet bulb 69˚C. Following cooking the rolls were administered a cold water shower for fifteen minutes then placed in a meat lug and stored in the meat cooler at 4°C for 8 to 12 hours. After chilling each restructured roll was reweighed to calculate cooking loss

The chunked and formed treatments had to be removed from the fibrous casing, and then manually cut into deli slices approximately 12.7 mm in thickness. The slices were then randomly separated into plastic bags. Three slices for the testing of bind, two slices for the testing of color, two slices for the testing of purge loss, and six slices for the sensory test.

Treatments

Treatments consisted of beef, beef and soy protein concentrate, pork, pork and soy protein concentrate, lamb, and lamb and soy protein concentrate.

Cooking Loss

Cooking loss is the amount of water or weight that is lost from the meat after it is cooked (Maddock, 2004). The chunked and formed deli roll was weighed prior and 8 to12 hours after the smoking process to determine cooking loss. Cooking loss was calculated as (raw weight/raw weight) x100 and reported as a percentage.

Protein Bind

The testing of the protein bind, or the strength and ability of the meat to combine together, was measured using the Instron Universal Testing machine (Model 1011, Instron Corp., Canton, MA). The Instron measures the amount of force it takes to push through the center of the deli slice. Three 12.7 mm slices were randomly selected from each treatment to make determinations.

Cooked Color

All treatments were tested using a chromameter (Model CR-200, Minolta Camera Co., Ltd., Osaka Japan). Following calibration (white plate, No. 20933026; CIE L* 97.91, a* -0.70, b* +2.44, Minolta Camera Co., Ltd., Osaka Japan), CIE L*, a*, and b* values were taken in two similar locations on both sides of the 12.7 mm slices. The CIE L*, a*, and b* values measured lightness redness, and yellowness.

Purge Loss

Two randomly selected slices from each treatment were weighed, individually packaged in 15.2 x 20.3 cm, 3-mil high performance bags (KOCH Supplies, Inc., Model FreshPak Vacuum Pouches, Kansas City, MO), and sealed with a vacuum packaging machine (KOCH Supplies Inc., Model Nirovac X 180 Digi-gas, Kansas City MO) prior to 24-hour storage at 4°C. After storage, the residual moisture was eliminated with a paper towel and individual slices were reweighed. Purge loss was reported as [(initial weight-final weight)/initial weight].

Sensory Analysis

The consumer sensory evaluation was of importance to the marketing aspect of the final meat product. Panelists (n=50) were surveyed to see if there was any difference in the likeness of the meats with the soy protein and without the soy protein. Demographic information was collected such as age and gender. Prior to analysis, samples were slightly thawed and sliced into 12.7 mm cubes and separated into plastic bags labeled with a randomly selected three digit number so as to not reflect a biased opinion based on the number selection. The consumer received six individual treatments for evaluation. Statistical Analysis

A randomized complete block design with six replications was utilized to test the treatment effects of soy protein, and raw material (SAS, 1999). Blocking reduced variation among replications caused by seasonal variation. When significant differences occurred for a response (p < 0.05), Duncan’s Multiple Range Test (Duncan, 1955) was performed to separate treatment means.

Results and Discussion

No differences (p>0.05) were revealed for cooking loss (Table 1). Further analysis shows that cooking loss decreased with the addition of soy protein concentrate. These results are confusing, when compared to past research. Previous researches have found that soy protein concentrate improves the

water-holding capacity and texture of pork in a restructured boneless roll through increasing protein functionality (Schilling et al., 2003, 2004). Pearson and Gillett (1996) also stated that as a result of imparting 70% protein, soy protein

concentrates are effective binders and extenders through improving the cooking yield, protein content, water binding, and flavor of meat products (Pearson and Gillett, 1996). Results from this study suggest that the soy protein concentrate might have been denatured or lost functionality prior to this research.

Table 1:

Effect of Soy Protein Concentrate on Cooking Loss of

Restructured Meat Products

Control SPC Standard Error

a a9.62 8.35 0.35 10.11a 9.16 a 0.37 9.16 a 8.65 a 0.22 a Means with like superscripts within the same row are not significantly different (P>0.05)

Purge loss is similar to cooking loss except it is the loss of water after the product has been stored in a freezer. Addition of soy protein concentrate revealed no difference (p<0.05) among treatments. This is similar to the results for cooking loss. Soy protein gelation occurs during heating as molecules form into strands in an ordered arrangement that provides increased protein and fat interactions. Lack of soy protein functionality in this research could be inferred to denaturation or lack of an ordered arrangement of the molecules. Pearson and Gillett (1996) noted that sectioned and formed products also have increased fat and water binding properties when soy protein concentrate is added to the formulation.

Meat Beef Pork Lamb

Table 2:

Effect of Soy Protein Concentrate on Purge Loss of

Restructured Meat Products

Meat Control SPC Standard Error aa3.57 3.46 0.17 Beef

aa4.58 4.04 0.16 Pork

aa3.12 3.23 0.06 Lamb

a

Means with like superscripts within the same row are not significantly different (P>0.05)

Color is normally the single greatest appearance factor that determines whether a meat cut will be purchased (Kropf, 1980). This experiment tested the product’s lightness, redness, and yellowness. No differences (p>0.05) were seen among treatments for lightness, redness, and yellowness. In all cases the control

variable without soy protein was darker than the sample with soy protein (Table 3). Since no differences (p>0.05) were detected, it could be inferred that addition of soy protein concentration to a restructured meat product would not be visually detectable by consumers. Redness in meat is caused from the amount of myoglobin present, which imparts individual species color. Myoglobin

concentration is species and age dependent. Myoglobin is the core pigment in meat and accounts for 80-90 % of the total pigment as it provides red color when oxygen is bound to the muscle and serves as a storage site for oxygen in the muscles of live animals (Hedrick et al., 1994).

Table 3:

Effect of Soy Protein Concentrate on Cooked Color in

Restructured Meat Products

Standard Error

Beef L* 45.86a 46.62a 0.34 a 14.52a 15.03a 0.45 b 9.29a 9.41a 0.76 Pork L 61.94a 60.01a 0.44 a 9.56a 9.96a 0.83 b 9.06a 9.96a 0.21 Lamb L 56.04a 53.74a 0.08 a 11.25a 12.34a 0.3 b 9.22a 8.92a 0.58

Meat Mean Control SPC

a Means with like superscripts within the same row are not significantly different (P>0.05)

Protein bind decreased (p<0.05) when incorporated in pork. Protein bind in beef demonstrated a minor improvement (Table 4). No difference (p>0.05) was

evaluated in any of the other treatments. Therefore this experiment established that soy protein concentrate could have possibly been denatured. Previous

research demonstrated that when incorporated into processed meats, soy protein concentrate also provides increased water absorption, binding, gelation, cohesion-adhesion, emulsification, and fat absorption (Fulmer, 1995).

Table 4:

Effect of Soy Protein Concentrate on Protein Bind of

Restructured Meat Products

Meat Beef Pork Lamb

a Control SPC Standard Error

aa2.06 2.07 0.95 2.59a 1.51b 0.03 2.10a 1.13a 0.19 Means with like superscripts within the same row are not significantly different (P>0.05)

Although there were no differences (p>0.05) among treatments for instrumental determinations it could be inferred that the treatments with soy protein concentrate were still acceptable, based on consumer sensory analysis.

Conclusion

The most prevalent factor in the outcome of this research is that the soy protein concentrate was denatured. Prior to the experiment the soy protein concentrate was exposed to humid conditions, which could have compromised its

functionality. Previous research demonstrated that when incorporated into

processed meats, soy protein also provides increased water absorption, binding, gelation, cohesion-adhesion, emulsification, and fat absorption (Fulmer, 1995). The results of this research were contradictory compared to previous research.

Originally the thought was that soy protein would increase meat quality because in Maddock’s Journal he stated that protein has the capability to increase product bind and water-holding capacity as well as many other important factors in meat (Maddock, 2004).

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