DESIGNING FOODS WITH DIETARY BIOACTIVE LIPIDS

Functional foods (such as margarines, mayonnaise, yogurt, salad dressings, soy milk, orange juice, etc.) containing dietary bioactive components are becoming increasingly available to consumers [114]. For the successful incorporation of bioactive lipids into certain classes of food products, it is important to overcome major challenges. Proposed approaches to develop functional foods with designed bioactive lipids are indicated in Figure 1.3. The major sources of these dietary bioactive lipids include microbial sources, fish, animal, and plant sources (Stage 1 of Figure 1.3).

Lipids being hydrophobic in nature may either have a positive or negative effect on the health of an individual. Within an individual’s diet, triac- ylglycerols are major energy sources, and several diseases such as coronary heart diseases (CHDs), diabetes, and obesity are associated with its overconsumption. However, the consumption of several other bioactive lipids such as polyunsaturated FAs exerts beneficial effects on human health [19]. Therefore, these beneficial bioactive lipids with health-improving ability can be added into different food products in different forms (Table 1.2).

The beneficial bioactive lipids may be present either naturally inside the multiplex matrix of food (e.g., milk, oil, egg, etc.) or maybe incorporated as functional ingredients (e.g., vitamins or phytosterols). The key element affecting the bioavailability of a BFC is its ability to confer health benefits, in addition to providing the conventional nutritional components. The food industry has responded to this by fortifying various food products with bioactive lipids. Designing and fabricating food products incorporated with bioactive lipids is a challenge to food scientists. The major challenges are [19]:

  • • To design food products with maximum health benefits from the dietary bioactive lipids by improving their bioavailability;
  • • To incorporate adequate levels of bioactive dietary lipids into food products;
  • • To prevent chemical deterioration of bioactive lipids during processing and storage of food products;
  • • To provide an accurate and clear awareness to the consumer of health beneficial effects of these dietary lipids;
  • • To understand and quantify the composite relationship between the dietary lipids and associated impact on health benefits.
Proposed approaches to design functional foods with bioactive lipids. Source

FIGURE 1.3 Proposed approaches to design functional foods with bioactive lipids. Source: Reprinted with permission from Ref. [81]. © 2014 Royal Society of Chemistry.

To confer several health benefits as shown in Table 1.2, the bioactivity of dietary lipids must be maintained during processing, storage, transportation, and utilization of a food product. However, the desirable sensory and physicochemical attributes, appearance, flavor, and texture stability of food products should not be adversely affected. Some bioactive dietary lipids (e.g., PUFAs, and carotenoids) are chemically liable, thus their bioavailability is influenced by oxygen, light, or pro-oxidants. While carotenoids are not stable physically, crystallize, and thus lose their bioavailability when incorporated into other food matrices. Few following issues emerge while designing and developing the food product containing bioactive lipids: 1

TABLE 1.2 Major Dietary Bioactive Lipids, Their Source, and Potential Health Benefits

Name

Examples

Sources

Health Benefits

Carotenoids

/?-Carotene, lutein, lycopene, and zeaxanthin

Pumpkin, collards, canot, tomatoes, tangerines, sweet potato, watermelon, etc.

Prevents cataract, cancer, coronary heart disease (CHD), macular degeneration, etc.

Fat-soluble vitamins; phenolic lipids

Vitamins A, D, E, and K; flavonoids

Carrots, spinach, avocados, vegetable oils, fruits, etc.

Prevents cancer, CHD, and urinary tract diseases.

Fatty acids

Docosapentaenoic acid (DPA), Eicosapentaenoic acid (EPA), docosahexaenoic acid (DFLA), stearidonic acid, a-Hnolenic acid (ALA), conjugated linoleic acid (CLA), arachidonic acid (AA)

Fish, certain algae, flaxseeds, walnut oil, collat'd greens, soybeans, borage, evening primrose (Oenothera), etc.

Prevents atherosclerosis, arrhythmias, weight gain, stroke, cancer, and immune response disorders, reduces blood pressure, improves bone health, mental health, visual acuity.

Phytosterols

Stigmasterol,

yS-sitosterol,

Campesterol

Algae, plants, vegetable oils

Coronary heart disease (CHD)

Oxidation: It is accelerated by heat, light, enzymes, metals, metallo- proteins, and microorganisms [28,105]. The products after oxidation of the bioactive dietaiy lipids not only reduce then bioavailability but also result in off-flavor development, color change, nutrient loss, and the formation of toxic compounds. PUFAs are most susceptible to oxidative reactions leading to off-flavor. The development of food products incorporated with bioactive dietaiy lipids, therefore, face a lot of challenges [19].

Carotenoids are also degraded chemically, either spontaneously or through free-radical initiated oxidations, during storage and processing of food products. Therefore, their biological properties are altered [12]. Several ketones and aldehydes are formed during thermal oxidation of /2-carotene

[71]. Peroxyl radicals disrupt the conjugated double bonds thereby resulting in rapid bleaching of /?-carotene [117]. These reactions cause undesirable color changes in food products during processing and storage. However, research studies have uncovered the cancer preventive effect of oxidized products from carotenoids by enhancing gap junction communication (GJC) [6]. Free radical scavenging ability is the fundamental function of carotenoids. Therefore, it is essential to prevent their oxidation in food matrices before consumption, in order to maintain their' desirable functions [19].

And dietaiy bioactive lipid, phytosterol, contains an unsaturated ling structure hence making them more vulnerable to oxidation reactions amid processing and storage in mass oil and oil-in-water (OAV) emulsions [15]. Esterified phytosterols have less oxidative stability than free phytosterols [108]. Few investigations have demonstrated that the oxidation products of phytosterols can cross the intestinal barrier at a low level, which might be connected to atherogenesis, cytotoxicity, carcinogenesis, and mutagenesis [111].

Fat-soluble vitamins (vitamin E) operate in the food and in our bodies. Several factors such as temperature during storage, oxygen, transition metals, light, and degree of unsaturation of co-existing lipids may influence the sapping of tocopherols in food matrices. The a-tocopherols (vitamin E) are present in biological membranes at a concentration of one part per 1000 lipid molecules thereby preventing PUFAs from getting preferentially oxidized prior to unsaturated FAs [14]. Restoration of vitamin E (a-tocopherols) is primarily achieved through dietaiy BFCs. It is thus critical to decrease the degradation of a-tocopherol (vitamin E) in food products to maintain adequate and efficacious concentrations in food products.

2. Bioavailability: It is imperative to know different components influencing the bioavailability of lipophilic bioactive agents since it helps in the efficient designing of food structure [81]. The oral bioavailability of any ingested BFC relies on the part that really achieves the objective site-of-activity in a biologically active form [97]. Assume the general bioavailability of an ingested lipophilic BFC is indicated by “F,” which relies on factors [5, 77, 81].

where, FL represents that fraction of a BFC released from a food matrix into GIT (gastrointestinal tract) with the goal that it ends up bioaccessible (Fl); Fa represents that fraction of the released BFC that is absorbed by the membranous tissue of GIT; FD represents that fraction of absorbed BFC that reaches the intended site-of-action when it is distributed amongst the various tissues of the body, e.g., liver, blood, heart, kidney, adipose tissue, muscles, etc.; F represents that fraction of a BFC that reaches the site of action in a metabolically active form; and FE represents that fraction of metabolically active BFC that has not been excreted.

All these parameters (FL, F , FD, F , and FE) vaiy with time. When BFC is consumed, a graph showing the bioavailability versus tune at an indicated site-of-action is obtained. The overall bioavailability (F) of BFC increases sometime after consumption followed by a decrease once it is metabolized, utilized, distributed, stored, or excreted. Tims, the bioavailability of consumed BFC can be obtained from the graph of bioavailability versus tune [81]. Many physicochemical and physiological factors (liberation, absorption, metabolism, distribution, excretion, and improving bioavailability) affecting the bioavail- ability of lipophilic BFCs have been substantiated [7,40].

  • 3. Water Solubility: Most of the bioactive lipids are insoluble, nonpolar, and, therefore, cannot be directly dispersed into water-based foods. The solubility of nutrients is one of the most important prerequisites for bioavailability [19].
  • 4. Molecular Structure and Physical State of Bioactive Lipids: The

physical state and molecular structure of dietary bioactive lipids affect their bioavailability. The bioavailability, absorption, and distribution of carotenoids inside the tissue are being adversely influenced by their molecular weight, polarity, hydrophobicity, and morphology [23]. Lycopene gets converted to c/s-form during processing possessing varied bioavailability from tram-isomer, due to differences in their solubility and crystallization in biological fluids. Transform does not result in tightly packed crystal structures due to then bent configuration [51]. Bioactive lipids in amorphous forms are typically more bioavailable compared to those in crystalline forms [19].

 
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