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High-pressure Processing: Opportunities and Challenges

Posted on:January 28, 2016
2016 CLC Processing Panel 2 photo of guacamole

Because high-pressure processing will not destroy spores, high-acid or acidified products may be more safely processed. They must also be refrigerated to protect quality. Most products that are now being processed using this technology are high-value items, such as guacamole.

January 28, 2016–Global Food Forums, Inc. — The following is an excerpt from the “2015 Clean Label Report,” sponsored by Loders Croklaan, RiceBran Technologies and SunOpta. 

PROCESSING PANEL, Speaker 2: Kathiravan Krishnamurthy, Ph.D., “High-pressure Processing: Opportunities and Challenges”

High-pressure processing is an old technology that has become economically feasible through advances in engineering. Indeed, it is estimated that the cost of this processing technology has been reduced thousands of times over the last 100 years.

There are a number advantages to foods offered by the technology, noted Kathiravan Krishnamurthy, Ph.D., Assistant Professor of Food Science and Nutrition, Illinois Institute of Technology, as the second speaker on the clean label processing panel.

These benefits include:
• Extended shelflife and improved food safety
• Pressure inactivates yeast, molds, bacterial cells and most viruses
• Minimal change in food flavor, color, texture, nutritional value, providing fresh-like characteristics
• Improved food quality
• Fewer/no additives, which helps answer demands for clean labels
• Can alter products high in protein/starch and produce novel food products

In high-pressure processing, the pressure is transmitted uniformly throughout the product. The product is not crushed, yet vegetative cells of both spoilage and pathogenic microorganisms are inactivated. It will also inactivate viruses and denature some enzymes. Because high-pressure processing will not destroy spores, high-acid or acidified products may be more safely processed. They must also be refrigerated to protect quality.

In addition, most products that are now being processed using this technology are high-value items, such as guacamole, oysters and ready-to-eat (RTE) meats. Oysters have been a real success story. High-pressure processing has been shown to inactivate viruses, extend shelflife, increase the yield of meat and minimize the labor involved in shucking.

One challenge with RTE meats has been the potential for Listeria monocytogenes contamination following processing. High-pressure processing of packaged RTE meats eliminates this concern and extends shelflife.

Applying this technology to juices and other agricultural commodities has been shown to enhance shelflife, provide a fresh-tasting product and enhance product safety with minimal adverse effects on nutritional content. However, any processor wishing to adopt the technology as a means for ensuring food safety has another challenge. They must validate that the process will deliver a minimum of a 5-log reduction (99.999%) to the target pathogen or a non-pathogenic surrogate which has been shown to have similar resistance as the target organism.

There are a number of potential opportunities for high-pressure processing. These include extended shelflife yogurts, fresh fruit and yogurt products; cheeses that have the flavor of raw milk cheeses or those with improved texture; products in which post-packaging microbial contamination may be removed, such the RTE meat example cited earlier; and enhancing functional properties of different products and ingredients, such as those with bioactive properties.

High-pressure processing is one of the few novel, non-thermal processes that has become commercially viable. Combining high-pressure processing and heat (pressure-assisted thermal sterilization) can be used for producing shelf-stable foods by inactivating spores. Processors wishing to adopt high-pressure processing need to do their homework beforehand and closely examine the pros and cons of the technology, including equipment costs.

Kathiravan Krishnamurthy, Ph.D., Assistant Professor of Food Science and Nutrition, Illinois Institute of Technology, kkrishn2@iit.edu, www.iit.edu/ifsh

 


Better Protein Ingredients Through Controlled Maillard Reactions

Posted on:January 21, 2016

January 21, 2016—Global Food Forums, Inc.—The following is an excerpt from the “2015 Protein Trends & Technology Report: Formulating with Proteins,” sponsored by Arla Foods Ingredients. 

Baraem (Pam) Ismail, Ph.D., chart for 2015 Protein Trends & Tech presentation

Enhanced stability and reduced protein/peptide interactions result when a protein is only partially glycated, and the Maillard reaction is stopped at the initial stage of an Amadori compound’s formation. [For larger PDF, click on image.]

By 2020, the global demand for protein ingredients is expected to reach 4.6 million tons and generate revenues of nearly $30 billion. But proteins can be problematic ingredients, and by using modified protein ingredients, a finished product’s performance can be positively impacted, said Baraem (Pam) Ismail, Ph.D., Associate Professor, Department of Food Science and Nutrition, University of Minnesota.

A common solution to several formulation challenges is to use protein hydrolysates, which can enhance digestibility, improve functionality, reduced allergenicity and and enhance bioactivity. Ismail explained this and more in her presentation titled “Considerations in Protein Ingredient Use: The Impact of Processing and Molecular Interactions.”

However, when proteins are hydrolyzed, they partially unfold, exposing groups that also can cause aggregation. That is, some peptides are actually aggregate promoters and will interact with other proteins, to create peptide-peptide interactions, and with carbohydrates to participate in undesirable Maillard reactions.

Aggregation is caused by both intrinsic factors, such as the source and structure of the protein, and extrinsic factors, such as heat, acid and protein concentration in the food system. Maillard reaction is an interaction of protein with carbohydrate, and its progression to advanced stages results in protein polymerization and reduced overall quality and shelflife. “One promising approach to limit aggregation is controlled Maillard-induced glycation, which involves covalent bonding of a protein and a sugar molecule,” said Ismail.

Research has shown one way to eliminate Maillard reaction-induced polymerization in nutrition bars formulated with whey protein isolate (WPI) is to substitute sorbitol for HFCS, a reducing sugar. This formula adjustment hinders Maillard browning reactions and the formation of high-molecular weight polymers.

Ismail discussed a study that looked at soy protein isolate (SPI) and soy protein hydrolysate (SPH) that were stored at high-water activity. The researchers monitored the change in free amine groups over time. The results showed a faster rate of aggregation in the SPH because of the release of higher levels of free amine groups that would participate in the Maillard reaction.

Solubility in beverages is a challenge when formulating with higher protein levels. Whey protein denatures between 60-70°C, causing the protein to unfold and expose hydrophobic residues and SH groups. These residues react and result in polymerization between proteins/peptides.

As the polymer grows, the protein falls out of solution. At the protein’s isoelectric point, solubility will be very poor. Fruity beverages formulated with whey protein are typically formulated to a pH below 3.5 to achieve clarity. Being good buffers, the presence of proteins necessitates addition of a considerable amount of acid to reach the desired pH. An excess amount of acid, however, can result in a finished beverage that is sour and astringent. These beverages are typically formulated to less than 4% protein, but 4.2% protein is required in order to make an “excellent source of protein” claim. One study using a partially glycoated whey protein achieved good solubility at concentrations between 5-7% protein.

Whey protein contains an “EF loop:” a three-dimensional structure that functions as a gate to hydrophobic residues. At the protein’s isoelectric point, the gate opens, exposing the hydrophobic groups, and polymerization results. However, it is possible to change protein functionality through glycation at specific sites, preventing the EF loop from opening.

By carefully controlling the Maillard reaction, an ingredient manufacturer can stop the reaction at a specific point, before the protein is completely glycated and before progression into undesired advanced stages. Advantages of this partial glycation are: increased net negative charge on proteins; increased surface hydrophilicity; reduced denaturation rate; reduced disulfide interchanges; and increased steric hindrance due to bulky polysaccharides. The net effect is enhanced stability and reduced protein/peptide interactions.

Food formulators should get as much information as possible from their protein supplier. By understanding how a protein was processed (and possibly modified), they can more accurately predict the sweet spot of optimal protein level with good product stability.

Baraem (Pam) Ismail, Ph.D., Associate Professor, Department of Food Science and Nutrition, University of Minnesota, bismailm@umn.edu, +1.612.625.0147

 


Of Allergens and Proteins

Posted on:January 15, 2016

Any novel food could potentially become allergenic. [Click on image for full-sized chart.]

Any novel food could potentially become allergenic. [Click on image for full-sized chart.]

January 15, 2016—Global Food Forums, Inc.—The following is an excerpt from the “2015 Protein Trends & Technology Report: Formulating with Proteins,” sponsored by Arla Foods Ingredients. 

There are a lot of myths about food allergens, including the myth that certain proteins are non-allergenic. In fact, every protein has the potential to become an allergen. The key to dealing with allergens is careful management within manufacturing facilities and clear communication to consumers on the food label.

Food allergies are abnormal responses of the human immune system to substances in food. “When an individual is exposed to protein, that exposure can stimulate the creation of IgE antibodies that create sensitivity to that protein. Individuals don’t have symptoms during the sensitization phase. The next time the individual is exposed to the protein, however, the body reacts and releases a host of physiologically active substances in tissues and the bloodstream,” explained Steve Taylor, Ph.D., Food Allergy Research & Resource Program, University of Nebraska, in his presentation titled “Allergens—It’s Really Just a Management and Communications Issue.”

Eight foods (cows’ milk, egg, crustacean, fish, peanut, soybean, tree nuts and wheat) are the most common causes of food allergy. These Big 8 are responsible for 90% of all food allergies on a global basis. Common allergenic foods in other countries include buckwheat in Japan and lupine in the EU. Kiwi was introduced into the human diet in the last half century and is now the most common allergenic fruit in Europe and the U.S., Taylor went on to say.

The most common allergenic foods tend to be consumed frequently and in relatively large quantities. With the exception of crustaceans, they are typically consumed in early life stages. Most are excellent sources of protein. Another factor that determines allergenic capability of a food is resistance to digestion in the stomach, which allows the proteins to enter the small intestine in an immunologically active form.

To predict the allergenic potential of a novel protein, one should first perform a thorough review of global allergenic literature. Explore if the protein ingredient is allergenic in other countries; if it contains a potentially cross-reactive protein; or if it is botanically related to other allergens. Insects are invertebrates, as are crustacean shellfish. Taylor recommended putting a warning on insect ingredients, such as “Not suitable for individuals with shrimp allergies.”

Food allergens are commonly classified into families by their shared amino acid sequences and conserved 3-D structures. Knowing if a novel food source contains any of these amino acid sequences could help predict if that food could one day become allergenic.

There are four main families of plant-based food allergens. 

Prolamin superfamily—this includes Ara h 2, which is present in peanuts. This family includes allergens in walnuts, peanuts, sesame, mustard and sunflower. It also includes gliadin, a component of gluten.
Cupin superfamily, which includes seed storage proteins, peanuts, soybeans and other legumes.
Bet v 1 family, which is present in birch trees.
Profilins, present in all species of animals and plants but not a major concern, because they are heat-labile.

There are also three main families of animal-based food allergens.
Tropomyosins—the major allergens of crustacean shellfish and, probably, insects.
EF hand proteins, which include parvalbumin, the major allergen in fish.
Caseins—the major allergens in milk.

Foods should not be marketed as non-allergenic. It would be more accurate to state that the product “contains no commonly known allergenic foods.” Companies working with novel protein ingredients might consider seeking insights from the FDA as to how that organization will handle new information about potential allergens, advised Taylor. Companies should also be aware that regulations for novel food products in other countries may differ from U.S. regulations. With clear labeling, consumers who develop allergic reactions will be able to avoid the offending food. Allergenic potential should not be a deterrent to marketing of novel food protein sources.

Steve Taylor, Ph.D., Professor and Co-director, Food Allergy Research and Resource Program, University of Nebraska, staylor2@unl.edu, +1.402.472.2833, www.farrp.unl.edu

 


Processing Technologies and Their Central Role in Clean Label Products

Posted on:January 8, 2016
Processing technology is a big part of creating clean label products consumers will accept.

In meeting the marketing department’s demands, packaging is the most visible—but also one of the most impactful—for delivering clean label products that are commercially viable. [©iStockphoto]

January 8, 2016–Global Food Forums, Inc. — The following is an excerpt from the “2015 Clean Label Report,” sponsored by Loders Croklaan, RiceBran Technologies and SunOpta. 

PROCESSING PANEL, Speaker 1: Jeffrey Andrews, “Technology: The Core Ingredient in Natural Foods”

Meeting the demands of an ever-changing marketplace, which includes Millennial moms among many other groups, is a challenge for food processers. Food processors must do market research to anticipate trends and directions, so they can introduce products in a timely manner. Meeting consumer trends can create demands with which R&D and plant personnel often struggle, since they may be technically infeasible, said Jeffrey Andrews, Sr. Director of Contract Manufacturing, HP Hood, presenting “Technology: The Core Ingredient in Natural Foods” for a panel on processing advances relevant for clean label products.

Technology is one of the best tools food processors have in their arsenal to meet these demands, especially technologies that help produce foods that have clean labels and/or appear fresher. When one steps back and looks at how the food industry has grown, there is a direct correlation between the development and implementation of new technologies and getting new and more desirable products to market.

There is a broad range of such technologies. They include filtration technologies; thermal processing technologies, especially high-temperature, short-time or agitating processes that produce minimal changes in flavor and texture; high- pressure processing which may be used for processing high-value products without altering characteristics; in-package technologies for pasteurization or sterilization; and packaging technologies employing new materials and/or modified atmospheres.

In meeting the marketing department’s demands, packaging is the most visible—but also one of the most impactful—for delivering clean label products that are commercially viable. I-beam film skeletons allow film properties to be modified through the insertion of components that expand the capabilities of the package. They allow for better control of moisture-vapor transmission, enhanced vitamin retention and the adoption of a lighter overall package.

Processors can also better manage oxygen in packages through gas flushes, utilization of modified-atmosphere packaging, pulling a vacuum or the addition of oxygen scavengers. If a decision is made to use any of the oxygen technologies, such as vacuum or modified atmospheres, processors also need to adopt packaging that best showcases the technologies.

Millennial moms are demanding consumers with a strong interest in clean label products. Oddly, in order to meet their demand for simple, fresh food, the food processors must turn to the technologist to make it happen.

Jeffrey Andrews, Sr. Director, Contracting Manufacturing, HP Hood,
Jeffrey.Andrews@hphood.com, 1-617-887-8440, www.hphoodllc.com

 


Processing, Characteristics and Uses of Extruded Plant Protein Ingredients

Posted on:January 5, 2016
Mian Riaz, PhD, on textured vegetable protein's characteristics as meat substitute.

Textured vegetable protein products can be made to look and behave like various meats, with similar composition, appearance, texture, water absorption and rehydration time. Cooking characteristics can also be similar.
(Click on image for larger PDF version.)

January 5, 2016—Global Food Forums, Inc.—The following is an excerpt from the “2015 Protein Trends & Technology Report: Formulating with Proteins,” sponsored by Arla Foods Ingredients. 

Vegetable proteins can be texturized and extruded into different shapes, forms and uses for a variety of applications. In some cases, this provides a more feasible option to increase the protein content of a food than working directly with the food matrix. While many plant protein sources can be used for texturized vegetable protein (TVP) products, soy is the most common. About 80-90% of the TVPs found in the market place today are soy-derived.

Other proteins that can be texturized include wheat, peanut, chick pea, green pea, lentil and yellow pea. But, “in order to create TVPs, the functionality, composition and behavior of the proteins used must be understood,” explained Mian N. Riaz, Ph.D., Director, Food Protein R&D Center, Texas A&M University, in his presentation “Processing, Characteristics and Uses of Extruded Plant Protein Ingredients.”

For example, vital wheat gluten is the primary protein component in wheat-based raw materials. It is very hydroscopic and sticky. Pea protein concentrate, with 46% protein, would typically also contain 17% starch, 18% sugars, 4% ash, 2.7% oil and 2% crude fiber. In contrast, a faba bean protein concentrate of 63% protein may contain only 0.1% crude fiber.

Soybeans can be made into flour, soy protein concentrate, grits or flakes. The process is very complex, with extractions, purification and concentration. Alterations in any step can impact the finished ingredient—and every process adds cost—which explains why soy protein isolates and concentrates are so expensive.

“Because of their higher cost, soy concentrates and isolates are rarely used alone in TVPs,” Riaz said. However, their addition improves water-holding capacity and protein content. There are at least 23 different types of soy protein concentrate for different applications, so it is important to specify the application to the vendor. The goal is to understand the functionality of the raw materials to give good texturization, he added.

It is essential to know the protein level, protein dispersibility index (PDI), nitrogen solubility index (NSI), oil and fiber content, and particle size of the raw materials. All of these properties affect texture in the finished product. Higher protein levels give firmer-to-rubbery textures. For example, at a 90% protein level, a very rubbery texture occurs, which is not desired. For textured vegetable protein products, ideally, protein should be about 50- 60% for a very good texture.

PDI and NSI are measures of a protein’s solubility in water and are related to the amount of heat treatment. “The PDI test is more rapid and tends to give slightly higher results than NSI,” said Riaz.

The ideal place to start for good texture is about 60 PDI. This attribute also affects color, with a higher PDI being lighter in color. Darker soy ingredients are typically used for feed, while lighter are used for human food products. Riaz continued to explain: “Oil and fiber content reduces [the] protein level by dilution and interferes with texturization. Soy hull fiber can cross-link with protein macromolecules, affecting structure and texture; typically, in these products, less fiber is better.”

When creating TVPs, native-state proteins are preconditioned with steam and water, where they begin to swell and unfold, and then cross-link during the extrusion process. Extrusion changes ingredients chemically and physically, and a new material is created.

An extruder is a continuous pressure-cooker to which water and raw materials are added, and temperature is increased within seconds. Depending on the type of extruder, there are many functions it can perform. Different protein products can be created, including chunk-style, shredded or structured meat analogs in any shape, size or cut.

For chunk, minced and flaked textured soy protein products, Riaz advised to use soy flour with 60-70 PDI, and 50-55% protein content. “Important properties include water absorption, oil absorption and a meat-like texture. Color can be added to make it look like beef or chicken, and flavors can also be used,” Riaz continued.

Meat analogs can look and behave just like any kind of meat with similar appearance, texture, water absorption and rehydration time. Cooking characteristics are also similar to meat. Applications include vegetarian diced-meat dishes, stew meat, jerky, barbecue, pot pie, pasta and more.

Mian N. Riaz, Ph.D., Director, Food Protein R&D Center, Texas, A&M University, mnriaz@tamu.edu

 


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