Encyclopedia
Please note this is a comparison between Version 1 by Nenad Naumovski and Version 2 by Lindsay Dong.
Functional foods and beverages are becoming one of the leading food products on the global market today. This is predominately due to the consumer, industry and research-related interests in the use of food-derived products for the management of several chronic conditions. The diversity of available functional food products also provides an opportunity for the use of fruit-based sorbets as a carrier of functional ingredients.
- functional foods
- product development
- nutraceuticals
- sorbet
- fruit ices
1. Introduction
The development of functional foods and beverages is one of the key areas that combine innovation whilst targeting consumers’ needs. Since their inception, functional foods have been defined or referred to as foods or beverages that claim to provide benefits beyond the existing nutrition found within the original product [1]. The value of the global functional food market (including beverages) was estimated at USD 203.64 billion in 2022 [2]. Along with the development of functional foods comes the increase in demand for various types of supplements, beverages and food products, which also drives this growth [3].
The addition of bioactive compounds to increase the functionality of a food product has attracted growing interest from the commercial food industry. Current research is only just beginning to unearth the potential health outcomes of combining functional bioactive compounds within marketable food items [1]. The health outcomes of functional food products range from prevention aspects related to various diseases to improving health status and potentially overall quality of life. Likewise, current trends in the food industry regularly change in response to consumer demand, and this is apparent especially in areas such as health and fitness. A key trend is the increased awareness and education surrounding the relationship between food constituents and health, resulting in food manufacturers shifting towards products that maintain a strong health position [4][6]. For instance, to promote healthy bone development, it is suggested that the consumption of calcium-rich foods is necessary in times of rapid physiological growth. Therefore, children who may not have access to calcium-rich foods or those presenting calcium deficiencies may benefit from the fortification of food products with calcium to increase bioavailability [5][7].
Numerous functional food products already exist, including dairy products, bread, juice and children’s cereals, which are commonly found in regions such as North America, northern Europe, including the United Kingdom, and to some extent in Australia. The increased market requirements, variety of products and consumption of functional foods are also associated with the increase of health-conscious consumers as well as new and existing food consumption trends that contribute to the consumer maintaining a healthy lifestyle without adjusting their current dietary habits [6][7][8][9][8,9,10,11].
2. Functional Food Vehicles
There are a variety of existing functional food products available on the current market [5][7]. Numerous products exist in the Australian market, such as calcium-enriched milk (Paul’s physical ©), cereals (Uncle Toby’s Plus Calcium ©) and soy milks (PureHarvest Soy enriched with Calcium ©). Likewise, there is an abundance of functional foods containing folate as a prophylaxis for the in utero development of neural tube defects such as spina bifida and anencephaly [10][11][12][28,29,30], including juices (Berri Orange Juice ©), cereals (Kellogg’s All Bran © and Sanitarium Weet-Bix ©) and extracts (Vegemite ©). In addition to the mandatory fortification of flour [5][7], there are also attempts to fortify a variety of functional frozen products, such as ice creams and sorbets, with bioactive ingredients. This includes amaranth-infused lemon sorbet [13][31], epigallocatechin gallate in strawberry sorbet [14][32], FroPro © whey protein chocolate ice cream, low-caloric ice creams (Halo Top ©) and Cornelian cherry-infused ice cream high in vitamin C [15][33].2.1. Sorbet as a Potential Functional Food
Among the functional products such as breads, berries and vegetables, frozen foods such as sorbets consumed among global populations are gaining attention. Sorbets as a functional food is one commercial method used to provide health benefits, extend food storability, preserve nutrients and provide palatability to the consumer [16][17][34,35]. Specifically, the Food and Agriculture Organization (FAO) classifies sorbets as a frozen water-based dessert that comprise two main ingredients: fruit juice and sugar (among other ingredients) [18][36]. Recently, sorbets have been used as a vehicle to deliver compounds to the body. A recent article showed that amaranth proteins could be embedded within the matrix of lemon sorbet as a potential functional protein source to increase bioactive peptides and antithrombotic activity [13][31]. Likewise, avocado, kiwi, honey melon, yellow melon and mango sorbets have also been studied with the embedded prebiotic inulin, which ultimately increased the organoleptic and pro-health features of the sorbets [19][37]. An Integral part of the development of a functional sorbet is evaluating the stability of the food matrix and the functional ingredient in its storage environment to ensure that the functionality of the target ingredient is not compromised. Several properties of the sorbet must be considered, such as acidity, moisture content and the addition of stabilizers. Furthermore, the release kinetics of the incorporated bioactive is dependent on numerous factors, including food vehicle choice of juice, interaction with other compounds, overcoming absorption problems and the overall toxicity of the functional food ingredient. The addition of functional bioactives can also elicit undesirable flavors and potentially alter the overall stability of the product. Therefore, it is essential to consider the current trends that exist and create techniques to develop a functional food sorbet [20][38].2.2. Developmental Considerations for a Functional Sorbet
2.2.1. Acidity
The optimal pH of functional food sorbets helps maintain their stability, assists with cost-effective production methods and avoids causing potential health problems. The pH of sorbets is dependent on the overall composition of the fruit juice, and to extend the shelf life as well as increase the integrity of the added ingredient, changing the pH environment is one of many different approaches used to maintain the stability of the added bioactive [21][39]. For instance, green tea constituents such as tea polyphenols and amino acids present a more comprehensive stability range in different pH environments in which they are highly pH-dependent (pH 3–6), especially favoring acidic conditions [22][40].
2.2.2. Moisture Content and Microbial Growth
Moisture content is one of the critical aspects considered when designing a functional food vehicle (in the form of a sorbet) due to its relationship with microbial growth and storage temperature [23][42]. Water activity (aw) is a direct measurement of the degree to which water found within a food system is available to enable metabolic reactions [24][43]. In many fresh foods, the aw exceeds 0.95, and over time the aw may decrease slowly (postproduction) due to environmental conditions such as exposure to microorganisms, atmospheric conditions and sunlight, for instance.2.2.3. Reduction of Microbial Growth
Similar to the osmotic mechanism of salts, sugars in food decrease aw [25][44]. Sugars act on cellular organisms via osmosis, drawing moisture out through a membrane to reach an equilibrium with the food product [26][27][46,47]. As a result, sugars have a profound effect on stagnating microbial growth. However, as sugars can be easily broken down through fermentation, it is essential to combine techniques such as freezing processes that halt microbial formation or implement the addition of stabilizers to prevent degradation of the food product. As a result, it is worth postulating that increasing the stability of a frozen functional sorbet matrix via the addition of microbial growth inhibitors such sugars may also increase the stability of the added functional bioactive compound and extend shelf life.2.2.4. Stabilizers
Stabilizers are added to ice creams and sorbets to provide smoothness in body and texture, reduce ice crystal growth during storage, as well as increase the stability of proteins. A relatively recent example is the addition of cellulose nanofibrils, which are a fibrous banana extract that have reduced the melting rate as well as extended the shelf life of ice creams and improved their sensory properties [28][48]. A second example is the protective effects that sugars have over proteins exposed to heat treatments during manufacturing processes [29][30][49,50]. Sugars stabilize proteins by inducing hydration via hydrogen bonding mechanisms to folded protein structures by acting as a substitute for water [31][51], as well as inhibiting heat coagulation that causes denaturation [32][52]. Reducing sugars, such as trehalose, are considered as exceptional protein stabilizers, as they are not affected by color and flavor changes that occur during denaturation processes such as the Maillard reaction [29][49].3. Compound Interactions between the Sorbet Matrix and Digestive System
Metabolism of the Functional Ingredients
There are several molecules identified in foods that potentially react or interact with bioactive compounds, which can reduce bioavailability. Appropriate fruit selection to produce a functional sorbet is essential to ensure that the selected bioactive does not bind to the food matrix or interact with other compounds. For any bioactive to reach systemic circulation, it must pass several phases of digestion, which can lead to drug–food interactions and food–food interactions that disrupt the effectiveness of the added bioactive compound. These interactions potentially affect the absorption, distribution, elimination and metabolism of the compound [33][54]. This commonly occurs when multiple compounds interact and have a synergistic or antagonistic effect on one another. It is also important to consider metabolic systems responsible for the breakdown of substrates in the body, which can have synergistic or antagonistic effects on the body. For example, the cytochrome P450 (CYP), an essential system of haem-proteins, is involved in the oxidative and reductive metabolism of food and drugs in the body [34][55]. Enzymes of the CYP system can be inhibited or up-regulated by food intake and potentially lead to toxic concentrations of other consumed compounds in the body metabolized by the same CYP system [35][56].4. Overcoming Absorption Issues
4.1. Nanoencapsulation
Various factors could potentially alter the integrity of ingested functional food compounds. For instance, the compounds with low stability in high pH environments may have reduced dispersion, digestion and absorption into the body when exposed to high pH conditions such as those experienced in the small intestine (Figure 1) [36][72]. As a result, residual amounts of compounds that remain post-consumption may become insufficient to produce desirable, beneficial effects in a pH environment not suited to the specific compounds’ pH stability range [37][73].Figure 1. Consumed bioactive ingredients are subject to pH changes that occur through the human alimentary tract that can inhibit the activity of dispersion, digestion and absorption into the body. Images developed using Biorender.com (2021).
Nanoencapsulation is one of the methods that is used to overcome this potential issue. Nanoencapsulation works by the principle of entrapping the active ingredients in a core surrounded by secondary materials (proteins, minerals) to form a nano-sized-capsule, protecting the core from the environment. Therefore, this technique provides a promising rationale to overcome the degradation of the substance outside of its pH range within the gastrointestinal (GI) tract [38][74].
4.2. Lipid-Based Delivery Systems
Another method to overcome absorption problems is the use of lipids to carry compounds of interest around the body, also known as a ‘lipid-based drug delivery system’ (LDS). Although lipids are not commonly found in sorbets (as sorbets are water-based food products), the use and application of this technology is potentially transferable to the use of sorbets as functional foods. This technique has gained significant interest in the delivery of compounds that have low water solubility. The LDS technique improves the absorption and bioavailability of food bioactives via influencing factors such as dispersion, digestion and absorption [39][79].
5. Trends for Functional Sorbets
5.1. Improvements in Product Acceptance
There are several considerations required for consumer acceptance of a food product. Moisture content contributes to the overall acceptance, particularly to the overall taste, texture and appearance at the time of producing the product and over the storage period [40][83]. For instance, the grittiness of ice creams or sorbets occurs due to poor manufacturing processes that result in the over-crystallization of solids and liquids, as well as lactose crystallization. Similarly, recrystallization (Ostwal ripening) and its formation in the post-production phase can be attributed to the change in temperatures during product storage due to melting of smaller formed crystals and the movement of the subsequent melted liquid to the surface of crystals with larger diameters [41][42][43][84,85,86]. Over-crystallization can be avoided through methods such as rapid cooling to the desired temperature below the melting point of that food product [17][44][35,87]. The same effect has also been observed in solid-state foods such as meats and vegetables through processes known as ‘snap freezing’ that aim to eliminate the formation of crystallized ice particles within the food matrix [45][88]. Other methods for controlling the ice particle formation in foods have also been tested, with promising results such as pressure shifting and ultrasonic and dehydro-freezing [46][89].5.2. Enhancing Taste
Consumer acceptance of food products is also affected by additives such as salt and sugars. Salt content is mostly determined by the consumers preferentially [47][90], although, despite consumer influence, salt enhances the flavor profile of foods. Salt elicits suppression effects of bitter foods [48][49][91,92] by modulating interactions of a subset of taste receptors (TAS2R38) [20][50][51][52][38,93,94,95]. The addition of salt into functional food products can therefore be utilized when bitter compounds (cocoa flavonoids and green tea extracts) are added to the matrix [20][53][54][55][21,38,96,97].5.3. Health Trends
The trends towards healthier food consumption have increased rapidly over the past decade, mainly due to the rise in consumer food knowledge [56][103]. For instance, a study by Vella et al. (2014) administered a questionnaire regarding functional foods that assessed consumption, motivating factors for consumption and awareness of health claims. The study found that among older adults, functional food consumption was high. However, there is a need to improve transparency regarding functional foods in line with nutrition and health regulations such as those specified within the EU, where it is required that any nutrition claims are clear, accurate and based on scientific evidence [57][58][104,105]. It has also been postulated that sodium intake is one of the most common nutrients that potentially determine a consumer’s increase in functional food consumption [59][106]. Overconsumption of sugars is one underlying factor contributing to the rise in global obesity [60][102]. Obesity is a public health issue, placing a burden on public health systems and increasing healthcare costs and related health outcomes such as cardiovascular disease, stroke, metabolic syndrome, diabetes and cancer [61][109]. As a result, improving the health status of functional foods by lowering their total energy content through sugar reduction is one method that may drive consumer consumption, which can be achieved through the addition of low-energy natural sweeteners such as Stevia, erythritol and Monk fruit extracts into the food matrix [62][101]. One of the most significant difficulties in promoting the consumption of functional low-energy sweeteners is replicating the taste and texture of the ‘original’ products. The natural sweetener Stevia is produced from the South American plant Stevia rebaudiana, with a sweet flavor almost 200–300 times stronger than sucrose.6. Conclusions
Given the rise in technological advancements and innovations in food preparation and the delivery and design of new food matrices, sweeteners and different conjugates, sorbets provide an excellent opportunity for the foundation of functional food products. Sorbets should also be considered for the valorization of food waste and incorporation of underutilized and food waste ingredients. This approach can aim to implement the zero-waste food production cycles with utilizing all components of the raw food material. Furthermore, extensive research is also needed to investigate the use of these food products and health recommendations for large populations. Emphasis should be placed on functional food interventions that focus on behavioral strategies, particularly habit-based interventions such as the consumption of medications or foods containing bioactive ingredients.
