This article was published in the March 2020 issue of Pet Food Processing. Read it and other articles from this issue in our March digital edition.
Palatability is the capacity of a food or an ingredient to stimulate the appetite of dogs or cats to encourage eating and satiety. These feeding experiences are dependent on packaging, formula, heat processing, and the freshness and stability of raw materials, making palatability a science demanding cohesion and respect to process.
“Palatability isn’t just restricted to the act of eating itself and doesn’t stop during the meal. The digestive part is also important, adding complexity to the field,” said Jean-Francois Herve, chief executive officer and founder, Birdstone Technologies, Seattle, Wash. “Since palatability is something perceived individually and each individual builds its own experience, the concept of palatability is very subjective.”
“Since palatability is something perceived individually and each individual builds its own experience, the concept of palatability is very subjective,” said Jean-Francois Herve, Birdstone Technologies.
The integration of sustainable nutrition is one of the many important long-term elements of palatability. It all comes back to the objective of a study. This could include acceptance of a treat, comparing a new product to its benchmark, or to simply give the food a hedonic note based on animal feeding behavior observation. Consistency of the formula and process is also key. Products that supply the same performance consistently will be perceived as better quality, Herve adds.
Breaking down the process
Although both are mammals and carnivores, dogs and cats have different sensorial equipment, anatomy and preferences. Both dogs and cats rely heavily on olfactory senses, sniffing before eating and enjoying multiple senses. Using their 1,600 taste buds, dogs can detect sour, bitter, salty, sweet and umami. They are generally not fans of bitter. A dog’s palatability increases with higher moisture, but quick eating habits (5 to 20 minutes) leave a short window to trigger olfactive neurons.
Cats also begin by sniffing, but their eating could stretch from two to 15 occasions – more opportunities to trigger olfactive neurons (positive) and more moments to change their minds about what they are eating (negative). Extended feeding patterns are also harder to observe. Felines employ 473 taste buds and detect sour, bitter, salty and umami, sweet being undetectable. Texture is important and crunch and easy-to-break pieces are appreciated.
Individual differences among animals necessitates including extensive expert panel testing with consumption being the key measure of palatability. The most common test is a paired comparison, known as a two-bowl, A-B testing, but other protocols like monadic testing (single bowl) can provide additional information, according to Abby Castillo, global palatant product manager, Kemin Industries, Des Moines, Iowa.
“Dogs are typically fed one or two meals a day in a home setting, so our palatability trials reflect that,” said Susan Jojola, Ph.D., manager, applied behavior research, AFB Research & Development, St. Charles, Mo. “Cats, on the other hand, are grazers.”
The two bowls test is well suited when the objective is to design a product that’s more attractive than another product. An acceptance test makes sure the food is eaten properly without refusal and is useful for treats. The Ranking Descriptive Analysis test focuses on the pet parent and its use is gaining in popularity. One market trend considers cat preference diversity with a multi-variety pack. This allows pet parents to zero in on what their cat prefers over time.
“With the increasing sophistication of pet food and variety of forms found on the market, it is becoming challenging to compare foods,” Herve said. “The complexity is increasing with toppers available to enhance the feeding experience. In this context, rather than comparing foods, it becomes more relevant to check that a specific food isn’t generating abnormal eating behaviors.”
Diana Pet Food, headquartered in Elven, France, uses expert panels to perform feedback to analyze the diets’ olfactory and gustatory attractiveness and the preference(s) of the pet. Extensive expert panels include a minimum of 40 cats or dogs over two days in order to represent the minimum of individual preferences. Testing considers consumption data including intake ratio and consumption kinetics and acceptability.
The human element
Because there’s no normalization around palatability measurement, it becomes important to consider the animal’s resulting behavior around the eating occasion. Measures of behavior can quantify pets’ responses to foods that are meaningful beyond what is consumed by describing how the dog or cat eats relative to what was eaten.
Through monitoring of external conditions, questions arise. Do the behaviors shown by the animal while eating indicate interest? Can the animal eat without being disturbed? Does the animal concentrate on the food while eating? Does the animal make repeat visits to the bowl? Is the cat demanding after an eating occasion?
“Cats require more finesse and a greater degree of balance in pet food and palatant formulation,” Castillo said. “This includes maintaining calcium-phosphorus balance when using salts as a key ingredient and considering whether or not ingredients in the diet could contribute to the formation of urinary crystals.”
Many of the most important behavioral clues are perceived by owners. Meowing could signal the cat is unhappy with the meal or they want more food. Another consideration is the animal’s head position on the bowl while eating. The ability of the owner to translate the behavior of their animal helps decode these experiences.
Creating attractive palatants
Texture and the quality of fresh, raw materials play a major role in palatability, as does the use of dry and liquid palatants. Created through a combination of technology and expertise, palatants gather the aromas and taste compounds that cats and dogs crave. As carnivores, animals take their energy from protein and fats. The encapsulating qualities of the fat contribute to the product’s flavor, nutritional value, texture and ultimate palatability. Therefore, it’s important palatants do not become encapsulated in the fat, making the order of palatant application key to maintaining accessibility and performance.
“Palatant form, protein sources, performance level and application rate are all considered,” said Preetha Banerjee, AFB Research & Development.
The hydrolysis of proteins can also help to boost a product’s performance in different ways. For fresh raw materials, biogenic amines are very important to analyze. Because biogenic and volatile amines can greatly influence the smell of a product, they play a major role in the ability of a finished product to be palatable. Small peptides can enhance taste, but too-small peptides (less than 3,000 Da) can create bitterness, according to Herve.
While freshness management, process control and the use of food or liquid agreeable to the palate are critical for palatability, matrix-dependent palatants are not one size fits all, Castillo says, and not all customers abide by the same definitions of palatability as explained by Preetha Banerjee, manager, customer engagement, AFB Research & Development.
“Each customer is different and has different definitions of palatability,” she said. “Palatant form, protein sources, performance level and application rate are all considered.”
Dry and wet food palatants
In dry pet food, palatants are generally added in a top coating after extrusion. Diana Pet Food recommends applying the fat, liquid and powder palatant sequentially, allowing time for each of the components to bond before proceeding to the next step. The company suggests mixing kibble for 45 to 60 seconds after each spreading sequence. Loss-in-weight feeders deliver powdered palatants consistently, and vibratory distributors help spread out the dry palatant. Lastly, tracers can measure for the real amount of dry palatant applied to individual pieces of kibble.
In wet pet food, palatability includes the level of grinding. Once texture is established, volumetric pumps accurately dose fat and liquid palatants through nozzles at a consistent, smooth rate. Some palatants are formulated with precursors of the Maillard reaction, which occurs during wet food retorting and generates flavor and aroma that stimulates the animal’s appetite.
Palatants can be included in the “meaty” part of the food or in the accompanying jelly/sauce, but if the jelly is too strong it could trap the flavors. Palatants used in wet foods must also consider high temperatures employed in the sterilization of cans or pouches, according to Aurélie de Ratuld, corporate responsibility director, Diana Pet Food. Overheating can destroy sensitive flavor components.
Historically, the retorting process was used to preserve pet food. Advantages include a more reliable product over time with less oxidation and off-flavors and no risk of microbial development post-processing. The natural addition of oxygen and the resulting alteration of the lipid’s chemical structure can make nutrition less available to the animal. Rancidity caused by degradation also serves as a sign of poor quality to the owner and could be dangerous to the animal’s health. The use of antioxidants help with the stability of fat, and an ingredient like yeast can help improve a product’s acceptance.
“The humanization trend in pet food has led to higher pet owner expectations and the launch of more premium products, especially in wet cat food palatants,” said Julie Ledyayev, customer engagement scientist, AFB Research & Development. “Making a palatable premium wet cat food is a challenging task due to the diverse processing conditions and formulations along with the complexity of cat food palatability in general.”
Flavor as art and science
Frozen foods, which continue to grow in popularity, have the advantage of keeping the food’s sensory properties intact while maintaining superior nutrition. Other new forms of pet food on the market including raw and frozen, infused, freeze dried and dehydrated usually do not demand the addition of a palatant. These diets appeal to pets and are also used to increase the appeal of a more processed food as a topper.
Treats on the other hand, offer other important functions such as training, health, education and pleasure. Designed to be highly attractive, treats contain a higher amount of palatants and aromas. Palatants for dry treats often mirror the processing of dry pet food products.
“When it comes to pet food, manufacturers want to elevate the nutritional qualities of the food,” de Ratuld said. “With treats, there is greater concentration on pleasure. Treats are also more expensive. Pet owners want treats to be fully eaten and see full happiness in the animal that’s consuming them.”
New ingredients, formulations and processing capabilities continue to refine product performance.
“Palatability and preferences depend on the animal and generalities are difficult to state. This makes research very difficult,” de Ratuld concluded. “It’s never black or white, it’s more gray.”
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