Download Probiotics as a Functional Food Ingredient in Frozen Foods

Probiotics as a Functional Food
Ingredient in Frozen Foods, Vegetables,
Fruits and Juices
Shreya Patel
FOS4041 – March 14, 2013
UNiUn[Type text]
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Introduction
In the United States, most probiotic products are either foods or dietary
supplements. A few probiotics are marketed as medical foods. Fermented dairy products
such as yogurt and kefir are typically associated with delivery of “beneficial cultures”,
however, other types of foods claiming to deliver probiotics have expanded to include
granola and candy bars, frozen yogurt, cereal, vegetables, fruit juices and oat based
cookies.1 With the demand for healthier and medicinal foods and uprising of vegan and
vegetarianism, researchers have found that probiotic products are the way to go.
Scientists and researchers are trying to give the same effect of fermented milk or kefir,
but to a broader spectrum of people including kids, youth, adults and elderly. The
researchers and scientists have opened up a new pattern of probiotics and are starting to
use it in frozen desserts, vegetables, and fruit purees. Researchers have also found that
many people are lactose intolerant or allergic and they have found ways to provide
probiotics to these special groups of people.
General Information
History of Probiotics
The word probiotics is derived from the Greek words “pro” and “biotos” which
means “for life”1. The first use of this word can be traced back to 1953 when Kollath
used it to describe the “restoration of the health of malnourished patients by different
organic and inorganic supplements1.” Probiotics were first immensely studied at the turn
of the 20th century at the Pasteur Institute in Paris. Eli Metchnikoff and Henry Tissier
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were some of the leading microbiologists in this research process and Metchnikoff was
awarded the Nobel Prize for Medicine in 1908. He concluded that encouraging the
colonies of the non-harmful gut flora by adjusting the pH would result in reducing many
health problems2.
What are probiotics and why are they important?
Probiotics can be described as a substance produced by one microorganism that
stimulates the growth of another, resulting in the opposite meaning of antibiotics.
Probiotics can also be defined as live microbial cell preparations to components of
microbial cells that have a beneficial effect on the health and well being of the host3.
Probiotics are found to be very beneficial and important to the human body because of
their resistant nature and ability to provide “good” bacteria to fight against the “bad”
bacteria that may cause serious illnesses that will be discussed later in the paper4.
Prebiotics and its relation to probiotics
Prebiotics are known as the food supply for the probiotics to feed on. It’s not as
gruesome as just described but it’s defined as a non-digestible food ingredient that
beneficially affects the host by selectively stimulating the growth
and/or activity of one or a limited number of bacteria in the colon4. Prebiotic’s relation to
probiotics is to help produce the health benefits that the probiotics offer to the host.
Prebiotics specifically refers to substances that undergo immense vitro and in vivo
testing3. Vitro testing is referred to as research done in non-living organisms such as a
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test tube or in an artificial environment for a culture medium. Vivo testing refers to
testing done in living organisms such as controlled clinical studies that involve humans3.
Probiotic Physiology & Requirements
Lactobacillus, Lactococcus, Enterocococcus, Streptococcus, Pediococcus,
Leuconostoc, and Bifidobacterium are some of the main forms of bacteria and are most
typically used strains of bacteria1. The two most widely used of these are Lactobacillus
and Bifidobacterium because of their strong resistance to the body’s harsh environment
and the ability to reach the Gastrointestinal Tract1. Lactobacilli are omnipresent in nature
and found in carbohydrate rich environments and are gram positive, non-spore forming
microorganisms that appear to be rod shaped1. Bifidobacteria was one of the first to be
isolated and seen by the microbiologist Tissier. They come in rod shaped forms, are nongas producing and are anaerobic microorganisms found in feces of breast fed neonates1.
Lactobacillus acidophilus and Lactobacillus casei produce lactic acid as the main end
product of fermentation5. Lactic Acid Bacteria is the “common” name for the bacteria in
the products that are consumed and they are generally fast acting, acid producing,
aerotolerant and prefer to be in conditions that are anaerobic1.
For a probiotic to have an impact on the hosts body there must be a minimum of
106 -107 colony-forming units per gram (cfu/g)6,7. Some researchers will argue that the
bacteria colony count needs to be higher depending on the type of bacteria used and the
product’s environment needs to be considered when forming a count that will be able to
withstand certain conditions. This will be applied when talking about the frozen dairy
products and the vegetable and fruit purees that contain probiotics. Some other
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requirements that probiotics must adhere to is that the probiotic strain must survive where
it is supposed to be most active. It also must be tolerated by the immune system and
should not be carcinogenic, allergic or pathogenic5. They should be preferably of human
origin and must be able to surpass low pH and high concentrations of conjugated and deconjugated bile salts5.
With the most recent research of probiotics being fermented into non-dairy
substances, the term synbiotics is commonly used. Synbiotics occurs when both
prebiotics and probiotics are used together in a food or supplement4. Scientists have
found that certain ice creams that are synbiotic (this will be discussed late in the paper)
have longer shelf lives and probiotic life span8.
Typical Probiotic Products and Health Benefits
As mentioned, probiotics have been found to help and reduce or even lessen many
health problems. Some diseases that probiotics have been tested to help are shown in
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figure 1 below5.
In addition to the aforementioned diseases, research shows that probiotics can help with
inflammatory bowel diseases and inhibition of some cancers7. Figure 1 helps describe the
health benefits of using probiotics but the type of probiotic bacteria is not known to
specifically help these health attributes5. One way that probiotics can help is through
preventing colon cancer5. It is speculated that the antimutagentic activity of probiotic
bacteria aids in preventing colon cancer through the detoxification of carcinogenic
metabolites, the alteration in procancerous enzymatic activity of colonic microorganisms,
stimulation of immune system and the influence on bile salt concentration5. Another way
that probiotics can benefit the body is by preventing allergies5. Probiotics prevent
allergies through the prevention of antigen translocation into the bloodstream. It can also
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prevent excessive immune responses to increase amount of antigen stimulation in the
gut5.
Some common probiotic products include, fermented milk, kefir, fermented
cheeses and the most popular source of probiotics, yogurt. Yogurt-like products are
considered to be some of the best-known food carriers for probiotics. Yogurt products are
considered “best known” because of their physiochemical and functional characteristics9.
Yogurt can be defined as “a coagulated milk product that results from fermentation of
milk by S. thermophiles and L. delbrueckii ssp”9.
Probiotics as a functional food in Frozen Dairy Desserts/Ice Cream
Preparing a meal with probiotics for children and fussy elderly can be challenging
and scientists have started to introduce probiotics into ice creams and frozen yogurts. The
main purpose for why researches feel that ice cream is a great way to introduce probiotics
to a bigger spectrum of people is because who doesn’t eat ice cream? It is a very staple
product in the US and many house-holds consume ice cream more so during the summer
but even during the winter time6. People are becoming more concerned with the foods
they eat and the health benefits. Functional foods is a more scientific way to describe
foods that have a benefit to the body. These can include probiotic or prebiotic organisms
and antioxidants such as berries or raw veggies that carry natural health benefits.
Scientists and researchers are seeing a promising future with adding probiotics to frozen
yogurt and ice creams. Some other ways scientists are trying to reach this goal is by
microencapsulation10. Microencapsulation is a process, which protects the physical
properties of the bacteria and also allows the stability of the organism to remain in the
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food. Spray Drying is one method of microencapsulation and it is used in many different
industrial purposes. It is mainly used because of its fast but low cost production and its
ability for high reproducibility10.
In a study, researchers are trying to put probiotics into ice creams through
different levels of inulin and sugar because inulin is considered to have prebiotic
characteristics to help with the growth of probiotics without affecting the taste of the ice
cream. Inulin is a non-digestible carbohydrate that contains naturally occurring
fructoolgiosaccarides, which carries some characteristics of dietary fibers and is an
interest for this study. This particular study’s goal was to keep a stable amount of 106107cfu/g of probiotics since this is the recommended level of probiotics to have an effect
on the body2. The tests researchers ran were to use commercial freeze-dried mixed
probiotic cultures grown at 37o F for 18 hours. They were mixed in 3 variables that had
skim milk with no inulin, skim milk with 1% of inulin, skim milk with 2% inulin, and
different levels of sugar were added. The end results concluded “that an increase in inulin
content of the fermented milk had stimulated the metabolic activities of starter bacteria
and improved development of acidity”2. They also concluded that the inulin had no affect
on the taste due to the high pH of the ice cream2. The last conclusion the researchers
made was that the sample with 18% sugar had the highest number of viable bacteria. The
bacteria that survived and improved the most were L.acidophillus and B.lactis. whoever
as the inulin levels increased their reproducibility also increased2.
In the Journal of Dairy Science, there was an experiment similar to the inulin and
sugar levels but they had an additional variable that includes the addition of synbiotics.
The first of the three types of ice cream that were tested was a probiotic ice cream made
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by adding probiotic microorganisms Lactobacillus casei and Lactobacillus rhamnosus.
The second was a prebiotic ice cream made with adding inulin and the third was a
synbiotic ice cream made with the combination of both the inulin and probiotic
microorganisms11. They concluded the experiment and found that all the ice creams had
viable number of lactic acid bacteria after the freezing and processing stages. In addition,
the numbers of probiotics to be considered effective on the body were also met. The ice
creams overall showed a good nutritional value and taste tests revealed consumers would
be interested in purchasing this product11. The ice cream that did the best in the
experiment was the synbiotic ice cream that had the most Lactobacillus casei with 2.5%
inulin11.
Problems with Probiotics in Ice Creams
The problem with fermenting ice creams and frozen yogurts is whether or not the
bacteria can survive the environments. The survival of the probiotic organisms in frozen
dairy desserts is influenced by many factors including acidity, pH, effect of the freezing
operation, time and temperature of storage and oxygen toxicity2. Adriano G. Cruz and
other researchers wrote a review about Ice Creams as a Probiotic Food Carrier which
talks about how ice cream is more of a useful and more well rounded food item that is
consumed by all age groups and providing them these healthy bacteria8. Cruz and his
researchers talk about the challenges they had with their “technological intrinsic
requirements related to their processing stages” 8 during the current ice cream processing
steps. One of the steps that have to be considered when air is incorporated into the ice
cream is the beating step and “overrun” of the ice cream, which could affect the end
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product8. Another problem with adding probiotics to ice cream is the storage of under
freezing temperatures and whether bacteria is able to withstand the temperature which
effects the inoculation of the bacteria into the ice cream8. Since the survival of the
bacteria in the ice cream is the main problem, Cruz and his team experimented with
adding probiotic strains that can survive low pH values7. They came to the conclusion
that Lactobacillus acidophilus La-5 and Bifidobacterium animalis Bb-12 were the most
stable with the addition of inulin and oligofructose in the ice cream and that the only
major difference between the two bacteria was the overrun of the ice cream8.
Probiotics in Frozen Vegetarian/Vegan Desserts
As mentioned earlier, vegetarianism and veganism is on the rise and more people
are starting to follow these healthier lifestyles. One of the problems with vegetarianism is
that many vitamins such as B12 is not a part of their diet since this vitamin comes mainly
from animal products. This next review talks about the use of probiotics in vegetarian
products and to be able to give the health benefits of probiotics to people who follow
these lifestyles for religious or personal beliefs. Firstly, in order for a probiotic to be used
in vegetarian products, it must be free from animal derived ingredients and in addition,
the organism must also survive the food manufacturing and retailing of the product12.
Lastly it must appeal to the consumers12. Soy products are high in protein and contain
raffinose and stachyose, which are oligosaccharides, and the fermentation of soy is
expected to have a better perseverance of the product and a better growth of lactic
acid13,14. Soy products that consisted of soy beverage, sugar, oil, stabilizer and salt were
mixed and heated and then aged at 4o C overnight. The probiotic count was taken right
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after freezing overnight and then colony count was taken again 6 months after storage12.
Throughout the storage there were regular examinations to check for cell viability or cell
deterioration12. The product was mainly examined for traceable differences in tastes and
other changes that would drive the consumer away from wanting to try this product. The
probiotic soy dessert was “acceptable to consumers” with majority of the tasters saying
that they would be interested in purchasing the product. The laboratory results showed
that there was a decrease in the number of probiotics than the number they originally
started with. Lactobacillus and Bifidobacterium were the two species that showed the
least change in beginning quantity and ending quantity of bacteria12. Experiments like
these show promising futures to expanding probiotics into dairy and non-dairy frozen
desserts.
A Promising Future of Probiotics
Probiotics In Fruits and Vegetable in forms of Purees or Juices
As previously explained the demand for probiotics for vegetarians and vegans is
rising, but there is also research trying to put probiotics into fruits and vegetables in
forms of juices or purees. This is targeted to populations who are allergic or intolerant to
dairy products or are on strict cholesterol free diets hence why many studies are being
done on fruit purees or juices and on cereals.
Some ways that scientists found that probiotics can be used in vegetables and
fruits is from their cell walls. Plant tissues are formed with small intricate structure
consisting of “internal cell walls, intercellular spaces, pores and capillaries”13 these
characteristics allows the microorganisms to grow and easily access the nutrient of the
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plant. Most microorganisms live in small pores or irregularities on the surface of the plant
and it is most beneficial for the probiotic growth13.
In one review, the researchers realized that the cell viability with acai pulp
fermented into milk helped the production of probiotics and was best kept in the 4 weeks
of storage9. With the thought that fruit pulps were helping the cell viability in fermented
milks, they added Lactobacillus and L.delbruekii in pomegranate juice and saw that the
cell viability was strong for the first 2 weeks of storage9. In another study that used
pomegranate juice, they observed that the critic acid, which is the main organic acid
present in this fruit was being consumed by all the probiotic organisms. This led them to
think that pomegranate juice is a “potential substrate” to producing probiotic juices13.
Another promising probiotic carrier is olives, they have been reported to have the
organism Lactobacillus that can tolerate the acidity and salt level of the olive and has
been binding effectively to the outer surface of the olive13.
Another reason why researchers feel fruits and vegetables are a promising carrier
for probiotics is because they mostly contain cellulose, which is not digested by the GI
tract. Fruits and vegetables also contain requirements necessary for probiotic adhesion to
plant tissue. Apples and pears show a protective effect on the probiotic microorganisms
during their passing through the GI tract, which results in the probiotics reaching the
colon and is able to benefit the body13.
Even though it is very challenging and intricate process of incorporating bacteria
into fruits and vegetables, it is something that would be highly advantageous considering
that fruits and vegetables are high in vitamins, minerals and nutrients and with the
implementation of probiotics it would be even more accepted through many age groups15.
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Probiotics in Cereal Grains
Cereal grains from whole grain to flour have also been an interest of study for a
potential probiotic carrier13. They have been studied in forms of breakfast bars, cereals,
bread, biscuits and cultured beverages. A reason why cereals are a prospect of probiotic
carriers is because they can be used to encapsulate the probiotic and their viability and
functionality can be easily maintained with this process13. The fermentation of cereals
such as oats, maize and wheat by probiotic microorganisms is beneficial because it
provides a better digestibility of the products. Wholegrain Liquid is a product that is
already on the market as a probiotic beverage. It is made up of organic ingredients such
as malted oats, maize, rice, alfalfa seed, pearl barley, linseed mungbeans, rye grain and
wheat and millet. It is fermented by Lactobacili and yeast cultures such as Lb. acidphillus
and Lb.delbeurkii. There are other fermented wheat beverages such as Hardaliye, which
is a fermented grape juice. It can be found in the Thrace region of Turkey14
Summary
In conclusion, the use of probiotics has many health benefits and in addition can
lessen the risk of many diseases such as colon cancer. An important effect of consuming
probiotics is reaching a healthier lifestyle that benefits a large portion of the population.
Researchers and scientists are looking for ways to broaden the use of probiotics to
different age groups and different populations. Using probiotics in various products other
than dairy based items because one is lactose intolerant, allergic or choosing not to eat
dairy because of a personal choice or belief. We can look forward to seeing products that
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have more of a medicinal focus and in products that are better viewed such as ice cream
or frozen desserts.
Application to Dietetics
Having an understanding of “good” bacteria versus “bad” bacteria is very
beneficial towards the Nutrition and Dietetics profession. Since many people
automatically assume that consuming bacteria is not good for the body16, it is the
dietitian’s responsibility to educate and inform the public that there is bad bacteria we
should not be consuming and there is good bacteria, such as probiotics and prebiotics,
that can be extremely beneficial to the body in one’s health. Dietitians should know
information that distinguishes the difference between bad and good bacteria and the types
of food that are associated with those types of bacteria.
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