Cereal Processing By-Products Within the Biorefinery Concept

Cereal grains comprise the principal component of human diet for thousands of years and therefore their processing represents a big asset of the food production chain. Wheat, rice, oat, barley and corn processing via dry and wet milling, pearling and malting includes complex procedures that generate an important amount of by-products that differ in their physical state and chemical composition.

Cereal processing by-products represent abundant and low-cost resources of phytochemicals (e.g. carbohydrates, proteins, dietary fibre, lipids, vitamins, polyphenols, inorganic and trace elements) with potential nutraceutical and pharmaceutical applications. To this line, their re-utilization and upgrade to high added-value applications is a great challenge towards the sustainable development of the agro-food sector for the years to come.

Oat processing and the alternative optionsThe target compounds and substrates are plenty and have been covered adequately through the whole book. Oat, its processing by-products and healthy components is a typical example of the available valorization and upgraded choices. Oats possess high amounts of water soluble fibers and particularly β-glucan (e.g. 2.2-7.8 g/100 g) as well as proteins (11-20 g/100 g). Their nutritional advantages in spite of diabetes and the control of blood cholesterol level have been attributed to the contained β-glucan.

To this line, the attribution of cereal β-glucan as functional ingredient has increased the interest concerning their incorporation in food formulations. Oat grains have been subjected to amylase hydrolysis (converting starch, carbohydrates and dietary fibers to maltose and β-glucan) in order to develop nondairy products. This process is monitored via enzyme kinetics modeling that optimizes the viscoelastic behavior of hydrolysates and simulates biodegradation processes of multienzymatic system based on cultures, e.g. hydrolysis of starch wastes.

Carbohydrate hydrolysis generates a drink that is consumed alternatively to milk products due to the lactose intolerance and cholesterol content issues of human populations, and a by-product (oat mill waste), which is usually dried and utilized as animal feed. The latest is rich in proteins and β-glucan that could be recovered using extraction and membrane technologies and utilized further in different applications, e.g. to replace fat of yoghurt and cheese.

Read full article in my Elsevier SciTech Connect Blog.

The Trend of Polyphenols

In the past 10 years, the growing interest of consumers has arised to a number of “superfoods”, which has been motivated by their high content of “polyphenols”. These compounds constitute a heterogeneous group of molecules which differentiate according to their chemical structure.

Polyphenols is a collective term for several sub-groups of compounds, but the use of this term has been somewhat confusing and its implied chemical structures are often vague even to researchers. Even today the scientific community is not consistent with a universal use of the term denoting plant polyphenols, since some call them plant phenols while some others use the term polyphenols.

The first definition of plant polyphenols in the scientific literature pertains to this initial utilization of polyphenolic plant extracts. As these compounds were highly required in the leather industry, considerable efforts were devoted from the beginning of the 20th century onwards to the study of the chemistry of tanning plant extracts in an attempt to tackle the structural characterization of their polyphenolic constituents.

Research on plant polyphenols shifted gears after 1945, as the discovery of paper chromatography and more and more other advanced analytical techniques made it possible to separate in numerous individual constituents.

In 1957 an industrial chemist Theodore White, pointed out that the term “tannin” should strictly refer to plant polyphenolic materials having molecular masses between 500 and 3000 Da and a sufficiently large number of phenolic groups to be capable of forming hydrogen-bonded cross-linked structures with collagen molecules (the act of tanning).

Today, the main reason for the interest of scientists and consumers for polyphenols is the recognition of their antioxidant properties, their great abundance in our diet, and their probable role in the prevention of various diseases associated with oxidative stress, such as cancer and cardiovascular and neurodegenerative diseases. Due to the considerable diversity of their structures, polyphenols are considered even more efficient than other antioxidants.

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Sustainable Food Systems Means Improving Production and Processing

Until the end of the 20th century, food loss and disposal of food waste were not evaluated as matters of concern. The prevalent policy was mainly to increase food production, without improving the efficiency of the food systems. This fact increased generation of food lost or wasted along supply chains.

In the 21th century, escalating demands for processed foods have required identification of concrete opportunities to prevent depletion of natural resources, restrict energy demands, minimize economic costs as well as reduce food losses and wastes. Besides, recent changes in the legislative frameworks and environmental concerns have stimulated industry to reconsider their management policy and in some cases to face the concept of “recovery” as an opportunity.

This tendency is becoming a major item for the food industry around the world, as resources become more restricted and demand grows. Indeed, food industry is increasing attention towards sustainability, which has been has been developed into a trendy word characterizing a frame of advances and modernization in the years to come. However, sustainability is neither easy to specify nor to implement.

In theory, it reflects the principle that we must meet the needs of the present without compromising the ability of future generations to meet their own needs. For instance, food processing ensures that the resources required producing raw food materials and ingredients for food manufacturing are used most efficiently. Responding to this goal, sustainability requires the maximum utilization of all raw materials produced and integration of activities throughout all the production-to-consumption stages.

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Sustainable Management of Olive Mill Wastewater: Treatment or Valorisation?

Olive oil is obtained from olive fruit by mechanical procedures, whereas its production involves one of the following extraction processes: i) discontinuous (press) extraction, ii) 3-phase centrifugal extraction or iii) 2-phase centrifugal extraction. Each of these processes generates in different forms and compositions.

The traditional olive pressing and the three phases continuous systems produce three streams: olive oil, olive cake (or kernel) and olive mill wastewater (OMWW). The annual world OMWW production is estimated between 10 and 30 million m3. The discontinuous process (not used often anymore) produces less but more concentrated wastewater (0.5–1m3 per 1000 kg) than the centrifugation process (1–1.5m3 per 1000 kg). The 2-phase centrifugal system was introduced during the 1990s in which the olive paste is separated into phases of olive oil and wet pomace (sludge by-product) that enables reduction of the volume of OMWW. Wet olive pomace is usually further extracted with n-hexane yielding olive cake oil, although it has no significant value because of the required energy for the drying process.

OMWW is a dark-colored, acidic (3< pH value <5.9) suspension of three phases: water, oil and solids (smashed particles of olive paste and kernel). It has a characteristic unpleasant odour and high organic content, whereas is claimed to be one of the most polluting waste produced by the agro-food industries. Typically OMWW consists of: 83-94% water, 0.4-2.5% mineral salts, 0.03–1.1% lipids and 4-16% organic compounds such as carbohydrates (2-8 g/100 g), pectin, mucilage, lignin and tannins.

Read full article in my Elsevier SciTech Connect Blog here.

Handbook of Grape Processing By-products Book – Authors’ Team Acknowledgments

After its launch few months ago, the Handbook of Grape Processing By-products  is continuously raising interest among researchers, academics, students, professionals and industrial partners activated in the field. Indeed, thousands’ of colleagues have already joined our LinkedIn and Facebook communities, participate in our open forums, discuss their needs, make questions, refer their case scenarios, indicate their problems and finally look for solutions and consulting in our interactive Food Waste Recovery – Open Innovation Network.

Book Presentation

A detailed explanation of the key features and hints of the book is accessible via an online book presentation which was organized on 20th of June by ISEKI Food Association (IFA) and watched live by numerous colleagues around the world. This was also an opportunity to catch up with colleagues and meet our audience. A recording of this book presentation can be viewed in the following video

Authors’ Team Acknowledgments

All these activities are organized by the FWR Group and volunteering actions of experts in the field. Therefore, I would like to take this opportunity to thank all group members and authors’ team for their fruitful collaboration and high quality work in bringing together different topics and technologies in an integral and comprehensive text.

Read full article here.

Factors Affecting the Bioaccessibility and Bioavailability of Bioactive Compounds

Bioactive compounds are found in fruits, vegetables and whole grains. They include an extremely heterogeneous class of compounds (polyphenolic compounds, carotenoids, tocopherols, phytosterols and organosulfur compounds) with different chemical structures (hydrophilic or lipophilic), distribution in nature (specific to vegetable species or ubiquitous), range of concentrations both in foods and in the human body, possible site of action, effectiveness against oxidative species, and specificity and biological action.

Several factors interfere with the bioavailability of antioxidants, such as food source and chemical interactions with other phytochemicals and biomolecules present in the food include some of the factors interfering with the bioavailability of bioactive compounds. For example, fruit antioxidants are commonly mixed with different macromolecules such as carbohydrates, lipids, and proteins to form the food matrix. In plant tissue, carbohydrates are the major compounds found, mainly in free and conjugated forms.

After consumption, the nutrients that are present in a food or drink are released, absorbed into the bloodstream and transported to their target tissues. Different nutrients differ in their bioavailability, which means that they are not utilized to the same extent. Release of the nutrient from the food matrix, effects of digestive enzymes in the intestine, binding and uptake by the intestinal mucosa, transfer across the gut wall to the blood or lymphatic circulation, systemic distribution and deposition, metabolic and functional use, excretion can affect nutrient bioavailability. It is mediated by external (e.g. characteristics of the food matrix, chemical form of the nutrient etc) and consumer internal (e.g. gender, age, nutrient status and life stage) factors. The bioavailability of macronutrients (carbohydrates, proteins and fats) is usually very high, e.g. more than 90% of the amount ingested.

Read full article in my Elsevier Scitech Connect Blog.

“Olive Mill Waste” Book Presentations & Author Team Acknowledgments

After its launch five months ago, the Olive Mill Waste book is continuously raising interest among researchers, academics, students, professionals and industrial partners activated in the field.

Trying to catch up with colleagues, meet our audience as well as explain in details the key features and hints of the book, an online book presentation was organized on 4th April 2017 by ISEKI Food Association (IFA) watched live by hundreds of colleagues around the world. A recording of this book presentation can be viewed in the following video:

https://www.youtube.com/watch?v=UIRd-wUpBZo&t=10s

Authors’ Team Acknowledgments

All these activities are organized by the FWR Group and volunteering actions of experts in the field. Therefore, I would like to take this opportunity to thank all group members and authors’ team for their fruitful collaboration and high quality work in bringing together different topics and technologies in an integral and comprehensive text.

Read full article here.

Presentation of “Nutraceutical and Functional Food Components” & Author Team Acknowledgments

After its launch five months ago, the Nutraceutical and Functional Food Components book is continuously raising interest among researchers, academics, students, professionals and industrial partners activated in the field.

While trying to catch up with colleagues, meet our audience as well as explain the key features and hints in detail, we also developed an online book presentation which was organized on 22th March 2017 by ISEKI Food Association (IFA). It was watched live by hundreds of colleagues around the world and a recording of it can be viewed here.

Authors’ Team Acknowledgments

I would like to take this opportunity to thank all authors for their fruitful collaboration and high quality work in bringing together different topics, approaches and strategies in an integral and comprehensive text. Some information about their background, expertise and contribution can be seen here.

Is Olive a Medicine?

                                                                   Photo Source: Pixabay

Olive oil, the production of olive fruit extraction, is the pillar of Mediterranean diet and its consumption is well known to provide multiple benefits to our health (e.g. for the cardiovascular system). Olive oil is nowadays highlighted and marketed as a “superfood” for human health not only due to its lipid profile (e.g. high oleic acid and low saturates), but also due to its high content in micronutrients such as squalene and polyphenols. The latter powerful antioxidants are in many cases advertised almost as an “elixir” that promise to relieve us against multiple diseases and health problems. Which of these advertised health claims have a scientific basis and how many of them are promises or just guesses?

Over the last two decades, olive oil has concentrated scientific attention not only in the Mediterranean area, but all around the world due to its beneficial effects in human health. This trend is mainly driven by its content in polyphenols. Hydroxytyrosol, tyrosol, oleuropein, eleocanthal, oleacein and other polyphenols with exotic names may not being well known to general public yet, but they already appear in the product labels in the shelves of supermarkets and pharmacies, promising to provide multiple benefits to consumers.

Polyphenols pass from the olive tree to olive fruit, olive oil and olive processing by-products (olive tree leaves and olive mill wastewater). Recent biochemical, pharmacological and other studies have shown that polyphenols possess strong radical scavenging capacities and can play an important role in protecting against oxidative damages and cellular aging. By far the most investigated olive oil polyphenol is hydroxytyrosol. Studies have been conducted in both cells and animals, whereas its antioxidant effect is nowadays taken for granted. Besides, hydroxytyrosol is currently in early clinical trials as a dietary supplement for patients with multiple sclerosis and as a measure preventing breast cancer in women with a relevant genetic predisposition. Oleuropein, which is mainly contained in the olive tree leaves, has also been investigated a lot. Oleocanthal, a tyrosol derivative whose ant-inflammatory role found similar to that of the drug ibuprofen in 2005, have also shown important bioactivities (e.g. against Alzheimer’s disease, several cancers etc), although most studies have been performed in cells and few of them in animals; thus it has not yet been fully evaluated.

Despite the so far promising results, the main weakness for these investigations is that their outcomes are to a great extent not systematically addressed. Olive oil is an extremely complex mixture of ingredients and thus it is not clear if findings based on experiments conducted with free compounds (e.g. hydroxytytorosol and oleuropein that exist in minute quantities in olive oil) can be extended to actual major constituents and olive oil (a natural product with great variability in composition). The problem of the levels of individual bioactive compounds in olive oil and the possible combined effects of various classes of bioactive compounds have not yet answered. In addition, the vast majority of the available studies have so far been conducted either in vitro or in vivo. Very few of them have been performed to reliable clinical trials in humans. The latter constitute the necessary test to prove the efficacy and safety of a component.

Read full article in my Elsevier SciTech Connect Blog.

What is the Difference Between Bioavailability Bioaccessibility and Bioactivity of Food Components?

The preparation of foods fortified with functional components requires integration of diverse aspects under evaluation. These include selecting of the appropriate source, detecting the bioactive compounds, applying separation and recovery techniques, performing toxicological assessments and finally making stability, activity and bioaccessibility measurements. At this point, it is important to define carefully the terms “bioavailability”, “bioaccessibility” and “bioactivity” (Figure 1) that are often used indistinctly to express similar functions.

Bioavailability includes gastrointestinal (GI) digestion, absorption, metabolism, tissue distribution, and bioactivity.  However, it has several meanings depending on the research area used to. For instance, from a pharmacological point of view, bioavailability is the rate and extent to which the therapeutic moiety is absorbed and becomes available at the drug action site. From the nutritional point of view (that is of particular interest in the current book), bioavailability refers to the fraction of the nutrient that is stored or being available in physiological functions. It is a key term for nutritional effectiveness, as not all the amounts of bioactive compounds are used effectively by the organism. For example, when different foods come in contact with the mouth or digestive tract, various interactions may take place affecting phytochemical bioavailability (e.g. fat enhances quercetine bioavailabilty in meals). Therefore, bioavailability expresses the fraction of ingested nutrient or bioactive compound that reaches the systemic circulation and ultimately utilized.

Before becoming bioavailable, bioactive compounds must be released from the food matrix and modified in the GI tract. Thus, bioavailability includes the term bioaccessibility. Indeed, it is important to analyze whether the digestion process affects bioactive compounds and their stability, before concluding on any potential health effect. Bioaccessibility is defined as the quantity of a compound that is released from its matrix in the gastrointestinal tract, becoming available for absorption (e.g. enters the blood stream). This term includes digestive transformations of foods into material ready for assimilation, the absorption/assimilation into intestinal epithelium cells as well as the presystemic, intestinal and hepatic metabolism. However, beneficial effects of unabsorbed nutrients such as calcium binding of bile salts in the tract are missed by definitions based on absorption. Bioaccessibility is usually evaluated by in vitro digestion procedures, generally simulating gastric and small intestinal digestion, sometimes followed by Caco-2 cells uptake.

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Nutraceuticals and Functional Components in Nutrition and Food Products

Foods contain major and minor components as well as bioactive compounds (e.g. antioxidants, peptides, carbohydrates, lipids, glucosinolates) that are of primary importance for human nutrition. Consequently, their importance has initiated a surge of research and product development in the food industry. In order to adapt to these consumer drivers and enhance the physiological functionality of inherent nutrients, the food industry is developing the so-called “functional foods”.

The latest term was born in Japan. Indeed, Japanese were the first to observe that food could have a role beyond gastronomic pleasure and nutrient supply to the human organism. Japan is the first country to legislate these products in the FOSHU (Foods of Specified Health Use) legislation, whereas it has the highest number of functional foods on the market. Europe and the American countries incorporated later this concept.

The American Dietetic Association (ADA) classified in 2004 all food as functional at some physiological level, pointing out that “the term functional food should not be used to imply that there are good and bad foods“. In addition, it denotes that “all food can be incorporated into a healthful eating plan ─ the key being moderation and variety“. Whole foods like fruits and vegetables represent the simplest example of functional foods since they are rich in bioactive compounds that protect body’s cells against oxidative damage and reduce the risk of developing certain cancers.

Read full article in my SciTech Connect Blog.

How do Emerging Processing Technologies Affect Nutraceuticals and Functional Food Components?

Foods contain major and minor components as well as bioactive compounds that are of primary importance for human nutrition. The importance of these compounds accelerated the development of innovations in the food industry, generating the so-called “functional foods” and “nutraceuticals“. Whole foods like fruits and vegetables represent the simplest example of functional foods, as they are rich in bioactive compounds and have a well-established protective role against the development of diseases.

Nutraceuticals represent any substance that provides medical or health benefits, including the prevention and treatment of diseases. Contrarily to functional foods, nutraceuticals are commodities derived from foods used in the medicinal form of pills or capsules. The preparation of foods fortified with functional components requires integration of diverse aspects under evaluation. These include for instance separation techniques, toxicological assessments, stability and activity tests.

On the other hand, processing has an impact on the final food products. Applied technologies may influence the content and effectiveness of nutrients, e.g. loss of bioactive compounds or diminution of their functionality typically increases more and more as foods are processed, stored and transported.

Novel, non-thermal technologies (e.g. ultrasounds, high-hydrostatic pressure, pulsed electric field, high voltage electrical discharge, cold plasma) promise to treat foods without destroying the nutritional components and sensorial characteristics that are normally affected during heat treatment. The latest techniques are today applied in both research institutes and food industries, promising to shorten processing times, control Maillard reactions, improve products’ quality and enhance functionality. The implementation of these technologies together with other trends and practices of the food industry (e.g. nanoencapsulation, food waste recovery, emerging need for innovations etc.) have brought new developments, data and state of the art in the field.

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Olive Mill Waste: Time for Economically Feasible Solutions

Photo source: Wikimedia

The cultivation of olives and the production of olive oil have deep roots in the history of Mediterranean region. Nowadays, this tradition represents a very important asset for many countries, not only in terms of culture and health, but also in spite of wealth. However, olive oil production is accompanied with the generation of huge amounts of by-products and waste that leave a congested environmental footprint.

These materials are undesirable for the olive oil industry in terms of sustainability and environmental impact, but perhaps more important in view of high disposal costs. Therefore, they have been considered as a matter of minimization, prevention and treatment for as many decades as olive oil industrial production exists. Indeed, the proposed treatment methods and the respective literature and references are endless.

Despite this fact, olive oil industry remains unsustainable, with few opposite examples that confirm this rule of thumb. Why is this happening? Is it a matter of inadequate treatment technologies or is it about cost? Olive oil is a sector challenged by many directions. Consumers demand extra virgin olive oils of ultra-high quality, product’s final price varies a lot from time to time and local authorities demand from production units to reduce their environmental impact. Under these conditions, even cheap solutions that promise the total treatment of olive mill waste may collapse financially olive oil industries.

Consequently, most treatment solutions have been rejected in practice due to industries’ denial that claim to close down production and society’s tolerance that delays the enforcement of environmental legislations implementation. Can olive oil industries overpass environmental legislations forever? Does this consideration fall in the frame of the modern bioeconomy? Can they adapt any alternative strategies? The urgent need for sustainability within olive oil industry has turned the interest of researchers and professionals to investigate the management of olive mill waste with another perspective. This resource contains valuable components such as water, organic compounds and a wide range of nutrients that could be recycled.

The prospect of recycling ingredients from olive mill waste is a story that started few decades ago. For instance, solvent extraction had been applied to recover oil from olive kernel, which is one of the by-products derived from olive oil production. Nowadays, olive kernel is considered an established commodity similarly to olive fruit, whereas scientists focus on the recovery of polyphenols, the reutilization of irrigation water, as well as the production of compost to be used as soil amendment. Subsequently, there is a need for a new guide covering the latest developments in this particular direction.

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