Producing emulsified products without fat pockets

By Oscar Esquivel, Ph.D on 3/1/2008
MeatingPlace.com

The most abundant proteins in muscle fibers, actin and myosin, are insoluble in water, but can be solubilized through physical action in solutions containing 4 percent to 5 percent salt. A protein exudate is then obtained, which is capable of coating other components of the meat system, such as fat particles, muscle, connective tissue and other inclusions.

Typically, an emulsion consists of a discontinuous phase composed of fat and other, larger particles dispersed in a continuous aqueous phase of solubilized protein material. These coated components form a matrix that coagulates upon heating, forming the typical solid and elastic structure of sausages and meat emulsions. A meat emulsion is the result of the efficient formation of an emulsifying phase, which coats suspended fat particles and physically restrains them after the protein matrix gels due to heating. Fat particles are then prevented from coalescing and forming fat pockets.


Factors affecting emulsion stability
Emulsion stability is very important to the quality of sausages and emulsified products and to prevent defects such as fat pockets and mushy texture.

"Fatting out" in a meat emulsion can be associated with considerable moisture losses due to formation of channels during the cooking process. Moisture and liquefied fat can leak and migrate to the product surface through these channels. In stable products, moisture loss and/or fat coalescence will be minimal.

Fat stability is mainly affected by three factors: the biophysical properties of the emulsifying film coating the fat particle, the gelation properties of the protein matrix and the physical characteristics and cellular integrity of the fatty tissue. Salt concentration and type of salt also affect the amount of extracted protein, which has a direct impact on emulsion stability. There is evidence that decreasing sodium chloride levels from 2.5 percent to 1.5 percent might reduce emulsion stability and produce undesirable texture. By reducing the amount of salt, there's also a decrease in the amount of solubilized protein available to coat and physically restrain the fat particles.

The amount of added fat and its relative surface also are important factors to consider for emulsion stability, given that it is necessary to fully coat the total surface of fat particles with a film of solubilized protein. Assuming there's enough soluble protein in the aqueous phase of the emulsion, the meat batter is more stable when fat particles are smaller (greater relative surface) leading to more efficient distribution of the fat particles throughout the continuous protein phase. However, if the fat relative surface area is greater (from excessive chopping) than the mount of available soluble protein, then the film coating the particles becomes too thin and more susceptible to physical disruption when fat expands during the thermal process. The result is an unstable emulsion, fat pockets and a loose and less flexible texture.

Increased thickness of the protein film may also influence emulsion stability. High temperatures at the end of the chopping process may result in a protein film that's too thick and inflexible, which will tend to fracture during fat expansion upon cooking. Thinner protein films will form a series of pores that could act as "escape valves" to hot expanding fat.

Several factors related to fat's characteristics can influence emulsion stability. Some reports mention that it is easier to emulsify short-chain saturated fatty acids than their longer-chain counterparts. The degree of saturation is also important; in fatty acids with similar chain length, it is easier to emulsify those that are less saturated. Similarly, there seems to be a relationship between the melting point of the fat and its degree of dispersion and absorption by the inter-phase protein film.

Meat batter viscosity decreases at temperatures closer to that of the fat melting point, and since fat particles are less dense than the aqueous phase, they tend to float to the surface. These floating particles are less likely to be coated by the protein film and will be prone to coalesce during the thermal process. Research that has investigated various types of fat shows that regardless of the final chopping temperature, at lower levels of fat addition, all kinds of fat yield stable emulsions. However, at higher levels of fat addition, those with higher melting points are more stable. As a rule of thumb, aim for final chopping temperatures below 63 degrees F, 53 degrees F and 43 degrees F for fats of beef, pork and poultry origin, respectively.

During cooking, the protein matrix undergoes various changes. From 104 degrees F to 122 degrees F, myosin starts to denature, and the gelation process starts. Close to 140 degrees F, collagen solubilization initiates. Finally, the structure is consolidated between 158 degrees F and 176 degrees F, when actin denatures.

Fat within this system starts to liquefy before thermal denaturation of the proteins and is completely molten before the protein matrix gelation is completed. Therefore, it is essential to have a balanced interaction between the fat and the protein film at the emulsion inter-phase that could stabilize liquid fat before gelation of the protein matrix. Both the inter-phase protein film and the protein matrix must be stable and cohesive enough that the exudation of melted fat through the structure and the subsequent formation of coalescing spots in void spaces are prevented.


Estimating emulsion stability
Estimating emulsion stability involves measuring the amount of fat and/or moisture released after the cooking process. Measuring electrical conductivity of the raw batter also is a good index of stability, given that an aqueous phase in the presence of salt would conduct electricity better than a system where a fat separation process has started.

Making a graphic of electrical conductivity as a function of time during the chopping process allows you to visualize the point where structural changes in the emulsion start. Some people even report that devices with fiber optics technology could predict the moment when an emulsion becomes unstable.

However, even though these points could be estimated, it would be too late to correct the problem. These techniques are useful research tools to establish historical records that eventually could be related to specific conditions. Unfortunately, no visible, reliable signs are readily available that could tell a processor how stable a meat batter is. Establishing good records and being consistent with manufacturing practices are still the best alternative.

Filipino Livestock Farmers Acquire a Cutting Edge

PHILIPPINES - Good news is just around the corner for livestock and meat exporters of the Philippines, says Agricultural secretary Arthur Yap.

Having been hit badly by the strengthening peso the industry will take relief with the extension of the Agricultural Competitiveness and Enhancement Fund (ACEF) until 2015.

Yap said Congress' approval of the law will allow the Department of Agriculture (DA) to use the P7.4 billion funds to bankroll much needed projects meant to sharpen the competitiveness of Filipino farmers in the face of global free trade.

Yap said among the steps he has undertaken is to order the National Meat Inspection Service (NMIS)to waive the collection of inspection and laboratory fees on pork and pork products.

To support this, he said the DA will establish regional laboratory facilities in the cities of Cebu, Cagayan de Oro and other key export growth centers so that laboratory testing will be cheaper.

Yap said the DA's efforts to promote Philippine livestock and poultry products overseas is expected to bring Mindanao's frozen pork products to Singapore and Japan in the months to come.

On the other hand, Yap said the DA is pursuing measures to boost the incomes of livestock and poultry exporters is keeping with the mandate of President Arroyo for the DA to focus on food production and job generation.

DA reported that the gross value of livestock and poultry production shot up by 5.04 percent to P163.2 billion and by 6.77 percent to P117.7 billion in 2007, respectively.

Poultry and Pork Production Key to Prices

CANADA - The Saskatchewan Ministry of Agriculture expects levels of pork and poultry production and the volumes of meat in cold storage to be key factors influencing live hog prices during the remainder of 2008, writes Bruce Cochrane.

Live hog prices showed improvement in February but they appear to have peaked turning downward over the last few weeks.

Brad Marceniuk, a livestock economist with the Saskatchewan Ministry of Agriculture reports U.S. slaughter numbers continued to increase in early 2008 putting more pork into U.S. cold storage while the volumes of poultry in cold storage have also been significantly higher, pressuring meat prices overall.

Brad Marceniuk-Saskatchewan Ministry of Agriculture

U.S. pork demand continues to be good but the problem is, again, we've had increased pork production early in 2008 so production continues to increase while demand is still relatively strong but that still has caused U.S. pork in cold storage numbers to be up...up over about 100 million pounds from December 31, 2007 to January 31, 2008.

You combine that with poultry stocks, that have been up about 100 million pounds, we've got a really big increase in meat in U.S. cold storage stocks.

That's about a 200 million pound increase from December to January which is a significant increase, again, which has been very negative to meat prices in general.

Overall meat production early in 2008 will be very important in determining where overall meat prices will go.

We need to see a decline in pork production and poultry production and that should help prices improve if we do see that.

Marceniuk points out the February Statistics Canada report indicates Canadian hog production is declining and, while the December USDA report showed U.S. hog production was increasing, recent large losses will result in U.S. production starting to come down shortly as well.

He predicts North American consumption will continue to be important but he stresses we do need to see increased exports and countries like China, Japan and Russia will be very important in helping reduce those North American cold storage levels.

USDA Outlook Report Bleak for Pork

First-quarter U.S. pork production is expected to be 5.92 billion pounds, 9.6 percent above the same period last year, according to USDA's March Livestock, Dairy and Poultry Outlook Report. Total commercial pork production this year is expected to be 23.1 billion pounds, 5.4 percent above 2007.

     First-quarter live-hog prices are expected to be $40 to $41 per hundredweight, 12 percent below the same period a year ago. As a result, many pork producers are operating at losses near $30 per hog.

     Meanwhile, gains in cold storage may signal a slowdown in pork demand. February's beginning stocks of frozen pork grew significantly beyond recent levels. Frozen pork levels on Jan. 31, were 563.6 million pounds, 16 percent above year-earlier levels. Larger-than-expected increases suggest that pork products are entering the supply chain faster than they are flowing through to domestic and foreign consumers.

H5N1 source: China, gene study suggests

from WorldPoultry.net
March 24, 2008

Researchers have now suggested that southern China may have been the source for much of the spread of the H5N1 bird flu virus.

Reuters has reported that flu experst have found that a genetic analysis of the highly pathogenic H5N1 virus shows that strains that appeared in Vietnam, Thailand and Malaysia in 2002 and 2003 closely resemble a strain from poultry markets in China's Yunnan Province.

It was reported in the Journal of Virology that the two viruses found in poultry in China's Hunan province in 2002 and 2003 were most closely related to viruses from Indonesia.

"These results suggest a direct transmission link for H5N1 viruses between Yunnan and Vietnam and also between Hunan and Indonesia during 2002 and 2003," wrote the researchers*. "Poultry trade may be responsible for virus introduction to Vietnam, while the transmission route from Hunan to Indonesia remains unclear," they wrote.

The H5N1 bird flu virus was first seen in a goose in southern China's Guangdong province in 1996. The virus re-emerged in 2003. Since then, H5N1 bird flu has been found in more than 60 countries and territories. It has killed 236 people out of 373 infected in 14 countries -- Myanmar, Turkey, Djibouti, Azerbaijan, Egypt, Pakistan, Iraq, Indonesia, Thailand, Vietnam, China, Nigeria, Laos and Cambodia.

The team of researchers to find out if H5N1 viruses all descend from one type. "Due to the lack of influenza surveillance prior to these outbreaks, the genetic diversity and the transmission pathways of H5N1 viruses from this period remain undefined," they wrote.

In 2007, a team at the University of California Irvine reported that Guangdong appeared to be the source of renewed waves of the H5N1 strain, but Chinese officials denied the report at the time.

* Included Guan Yi of the University of Hong Kong and Robert Webster of St. Jude Children's Research Hospital in Memphis, Tennessee.

Poultry feed prices will increase more

from WorldPoultry.net
March 24, 2008

Consumers will see another major run-up in food prices this summer due to the competition for raw materials, the American Feed Industry Association (AFIA) board of directors was told at its recent meeting.

AFIA President & CEO Joel Newman, in his state of the industry report to the AFIA board, said Congress and the Bush Administration must recognise that US$5 a bushel corn - and similar price jumps for soybeans and other food grains - can no longer be viewed as anomalies or temporary. "Five dollar corn looks to be closer to the new ‘normal," Newman said, adding ethanol’s use of corn will hit 27% of the US corn crop during the 2007-2008 crop year.

The AFIA Board was told the average 5% increase in consumer food prices experienced last year is just the beginning, with food prices likely jumping another 10-12% this year.

"The industry’s cost of production escalation has only just started to work its way through the system. Feed price increases will be pushed through the food chain over the next six months," Newman said, "Consumers can expect to see even higher prices for meat, poultry and dairy products."

Newman laid out the "perfect storm" of factors forcing food prices higher, starting with crude oil prices topping $100 a barrel and increasing demand for alternative fuels. Couple that demand surge with the effect of global livestock liquidation, particularly in the swine industry, increasing export demand for US grains and oilseeds to meet stronger global demand for animal protein, an 11% increase in world feed production – which has led to record low US stocks-to-use ratios – combined with a weak US dollar and significant increase in ag commodity speculators, and you have the inevitable pressure on US food prices, Newman said.

Supporting the AFIA internal analysis is a report released this week by the Coalition for Balanced Food & Fuel, of which AFIA is a member. In his report, presented at the Annual Meat Conference this week in Nashville, TN, Dr Tom Elam, president of Farm Econ, an analysis firm, said he estimates the cumulative costs to the food industry of the federal renewable fuel programme will be about $100 billion for 2005-2010. Elam said broiler industry input costs this year are up $3.4 billion (53 cents per bird); turkey input costs are up $646 million ($3.40 per turkey); swine input costs are up $2.9 billion ($38 per hog); cattle input costs are up $2.24 billion ($117 per fed beef animal) and dairy input cost are up $2.7 billion.

Preventing lipid oxidation of precooked meat

The advantages of precooked meats are clear, just as it's clear that "warmed over flavor" (WOF) isn't one of them. The product may look like meat, but it may taste like cardboard once it is reheated.

WOF is the result of lipid oxidation, which can occur when cooked meat is refrigerated. In a nutshell, the oxidation of lipids — or unsaturated fatty acids — creates a stale taste owing to the release of ionic iron during cooking. The onset of WOF is rapid during storage, with oxidized flavors typically detectable within 48 hours.

One obvious solution is to flash-freeze the product, though this approach may present taste and texture issues all its own.

For red meat processors, the good news is that beef and pork tend to be less susceptible to WOF than turkey and chicken. Further, WOF isn't associated with cured product thanks to the presence of nitrites, which function as antioxidants. The bad news: Science is still struggling to lick WOF, primarily by preventing or slowing oxidation.

Current practices emphasize introducing antioxidants to product, though other methods — including reducing heat during cooking as well as maintaining proper product temperatures before and after — also may slow or prevent oxidation.

Meanwhile, many common antioxidants may do the trick.


Solution No. 1: Butylated hydroxyanisole and butylated hydroxytoluene
Both of these phenolic compounds get the job done, particularly when used in combination. Oxygen reacts preferentially with the two rather than oxidizing fats and oils, thereby preventing spoilage.

Because both are strong synthetic agents, USDA is very specific about their use, having approved them at 0.01 percent of fat content for select applications, including fresh pork, brown-and-serve sausage, fresh Italian sausage, pre-grilled beef patties and fresh sausage made from beef or beef and pork.


Solution No. 2: Natural ingredients
Rosemary extract, one of the better-known natural antioxidants, is among the most effective in retarding lipid oxidation. In comparison to most synthetic solutions, it also is more thermally stable. Some applications blend rosemary extract and citric acid to achieve the same end.

Solution No. 3: Mixed tocopherols
A synthetic form of vitamin E, mixed tocopherols compare favorably to other antioxidants, though various types aren't created equal. So-called high-alpha types promote higher vitamin E activity and, as a result, perform well as nutrients. They also are good antioxidants, but not as good as low-alpha tocopherols, since the latter contain greater amounts of gamma and delta tocopherols, which promote higher levels of antioxidant activity.

As with BHA and BHT, USDA rules apply. Usage may not exceed 0.03 percent of fat content. And mixed tocopherols can't be used in combination with other antioxidants.


Solution No. 4: Citric acid
Best as an antioxidant in a secondary role, this ingredient is a weak organic acid found in citrus foods. It typically works synergistically with primary antioxidants to slow or prevent lipid oxidation.