Vitamins and minerals are essential micronutrients that assist the growth, development, and metabolic processes of human beings ^[1][22]. Micronutrient intakes are minimal for physiological functions to maintain health. However, their deficiencies affect up to two billion people and cause three million childhood mortalities each year ^[2][23]. Typically, as a strategy in the management of micronutrient deficiency, the bioactive compounds are directly mixed into the food matrix. However, in this way, nutrients are easily subjected to high temperature, oxygen, and humidity during the storage or cooking processes; thus, they are prone to chemical degradation, resulting in the loss of nutritional properties. Microencapsulation has been used as a valid technique for preserving the biological activity and stability of vitamins and minerals (Table 12). Among the vitamins, the one that is most often deficient worldwide is vitamin D. Vitamin D is a fat-soluble precursor of calcitriol, an active form of vitamin D, which is critical to the regulation of phosphorus and calcium homeostasis. The deficiencies of vitamin D can be countered by using food fortification strategies ^[3][15]. However, the challenge of including vitamin D in food is due to its high sensitivity to oxidation when exposed to heat, light, moisture, or oxygen ^[4][21]. To overcome this drawback, Zhu et al. ^[5][24] studied the microencapsulation of vitamin D with egg white and its application for bread fortification. The authors applied ultrasonication, an emerging technology that uses soundwaves above 20 kHz. Specifically, the authors layered vitamins on the surface of an aqueous egg solution (used as wall material) and sonicated the solution for 1 min at 160 W. The encapsulated compounds’ protection from photodegradation required a further coating with green tea catechin/iron. The encapsulated form of the vitamin proved to be more resistant to light and heat than the non-encapsulated type. In addition, the authors reported that the inclusion of free vitamin D in the dough tended to coalesce, merge, and form oily regions. Indeed, egg white microcapsules were proven to protect vitamin D from mechanical stresses. Bread fortified with microcapsules showed a higher vitamin D recovery (81.3%) than that with free vitamin D, indicating that the microcapsules embedded into food matrices were thermostable and that the vitamin D was protected from degradation to a certain extent. Accordingly, Constantino et al. ^[6][25] reported a rate of recovery of 88.65% for vitamin D microencapsulated in complexes and formed by amaranth protein isolates and lactoferrin after the baking process compared with the 64.63% obtained for the non-encapsulated vitamin. In both studies reported ^[5][6][24,25], the in vitro gastrointestinal digestion process of bread was performed, and it was reported that the greatest amount of vitamin D was released from the microcapsules in the intestinal phase. Specifically, Costantino et al. ^[6][25] reported that 22.98% of the vitamin was released in the first 5 min and 82.96% was released by 180 min for the encapsulated sample. Similarly, vitamin D in an egg white-designed microcapsule allowed 67% of vitamin D to reach the intestine in the active form. whereas the free sample allowed only 32% of the ingested vitamin to be absorbed in the intestine due to the degradation in the stomach ^[5][24]. In addition to vitamin D, microencapsulation has also been investigated to improve the thermal stability of some other vitamins during bread baking. Folic acid, for example, has been proven useful for reducing the incidence of neural tube defects, but there are concerns that it could mask vitamin B12 deficiency. A reduced form of folate, L-5-methyltetrahydrofolic acid (L-5-MTHF), is nowadays used for food fortification. However, it is susceptible to oxidation, leading to important losses during bread baking. Liu et al. ^[7][26] reported an important increase in L-5-MTHF stability during bread baking upon microencapsulation by spray dryer with modified starch as a wall material. In addition, the co-encapsulation of L-5-MTHF and ascorbate promoted the storage stability of bread and recovery of L-5-MTHF after bread baking as compared with free L-5-MTHF. The L-5-MTHF recovery rate also remained high after the scale-up process, passing by 97% for the pilot plant compared with 77% for the commercial bakery scale. Similarly, Tomiuk et al. ^[8][27] reported that L-5-MTHF encapsulated via a spray dryer using skim milk powder as the wall material remained highly stable (>80%) in white bread. Sodium ascorbate with skim milk powder as shell materials had an even better positive effect on the stability of folic acid. In contrast, Neves et al. ^[9][28] reported a higher thermal degradation rate of microencapsulated folic acid compared with its free counterpart when included in French-type bread. The results showed that the free folic acid degradation was completed at 155 °C/30 min, whereas the microencapsulated folic acid was entirely degraded at 100 °C/15 min. The authors reported that the high surface area of capsules and locating folic acid on the surface of particles could be responsible for this behavior.

Regarding minerals, major deficiencies are related to iron and zinc. A third of the population worldwide suffers from zinc deficiency, while more than half have an iron deficiency. Iron is an essential structural component of hemoglobin, myoglobin, and cytochrome-dependent proteins. Iron deficiency, the most common cause of anemia, affects 1.5–2 billion people worldwide. It is associated with diminished work productivity, lower immunity, and impaired cognitive development. Three main reasons for iron deficiency can be identified: inadequate iron intake, compromised bioavailability, and increased iron losses ^[11][29]. Food fortification is a dietary strategy that can be used to overcome this nutritional disease. However, food fortification may result in the undesirable color, odor, and taste of foods. Furthermore, iron may interact with food protein and lipids, decreasing its bioavailability. Iron encapsulation can assist with improving sensorial properties in fortified foods ^[10][11]. Bryszewska et al. ^[10][11] evaluated the bioaccessibility and bioavailability of microencapsulated iron in bread prepared by conventional and sourdough fermentation using the human epithelial adenocarcinoma cell line Caco-2. Besides the control, four bread fortified with two iron sources (ferrous sulphate and lactate) with or without ascorbic acid were produced. The iron bioaccessibility of the fortified bread after gastrointestinal digestion varied from 35.99 to 99.31%. Specifically, samples obtained with the conventional bread-making process showed the highest iron bioaccessibility. Furthermore, the percentage of iron transport efficiency showed no differences between the types of bread fermentation. In comparison with other samples, the microcapsules with iron and ascorbic acid showed a higher iron transport efficiency (13.78%). This effect is probably due to the antioxidative properties of this vitamin preserving iron in the divalent form, which is more available for transport by enterocytes.

Overall, the studies reported show that the inclusion of microencapsulated vitamins and minerals in bread increases their concentration and bioavailability. However, neither the studies on vitamin D and folic acid nor the one on iron microencapsulation evaluated the microcapsule’s inclusion effects on the rheological, technological, and sensory characteristics of bread. It has only been reported that the use of microencapsulated vitamin D avoids the coalescence, merging, and formation of oily regions in bread. However, it would be necessary to deepen other aspects related to the effects of the inclusion on bread quality and, on account of the bioactives lability, to conduct an in-depth assessment of its stability during the bread shelf-life.

Polyunsaturated fatty acids such as omega-3 and omega-6 are highly desirable in bread fortification as they could prevent cardiovascular and inflammatory diseases, cancer, and metabolic syndromes ^[12][30]. These fatty acids are very labile from a technological point of view and are susceptible to oxidative deterioration. Bread fortified with PUFAs could develop undesirable fishy flavors, resulting in decreased sensory qualities and food shelf-life. Indeed, the encapsulation of oils can inhibit or delay their oxidation and mask negative flavors and unpleasant tastes ^[13][31]. In addition, as reported by several authors, the encapsulation of oils could protect them in the gastrointestinal tract without altering their chemical characteristics ^[14][15][32,33]. Moreover, the addition of encapsulated oils in bread could affect most of the technological and sensory properties, such as bread volume, texture, fatty acids bioavailability, the bread’s oxidative stability, and sensory properties (Table 23).

González et al. ^[14][32] studied the fortification of bread with encapsulated chia oil using soy protein as the coating material and assessed the hydroperoxide values up to 14 days in storage. The research showed the protective effect of microencapsulation against oil oxidation. Indeed, bread with microencapsulated chia oil presented three-fold fewer hydroperoxides compared with bread with free oil. Moreover, the protein–polysaccharide matrix (soy protein isolate–maltodextrin–pectin) used as wall material for Himalayan walnut oil was able to prevent the bread oxidation in terms of peroxide value, anisidine value, and acid value during 8 days of storage. The soy protein isolate and pectin as wall material were able to delay fatty acid oxidation due to their antioxidant properties. In addition, the scanning electron microscopic analysis showed intact encapsulated oil bodies in the crumbs after baking, thereby demonstrating high omega fatty acid retention ^[16][34]. Sodium alginate, used as a coating material for the encapsulation of garlic oil by Narsaiah et al., ^[17][35] was reported as an effective barrier against oxygen and was useful for bread fortification. In addition to the coating polymers, the nature of the core had a significant impact on the oxidation of the fortified bread. Regarding this, Sridhar et al. ^[15][33] and Kairam et al. ^[18][36] demonstrated a synergistic effect between the mixtures of oils selected as the core material (garlic oil combined with fish or flaxseed oil) in reducing oil oxidation throughout the storage period. In these studies, the secondary oxidation products during a week of storage were lower in bread fortified with the oils blend (0.32 µmol of malonaldehyde/g at day 7 with fish and garlic oil as compared with 0.48 µmol of malonaldehyde/g at day 7 for bread fortified with only fish oil) ^[15][33]. Similar results were reported also by Kairam et al. ^[18][36].

Ojagh and Hasani ^[19][37] fortified bread with liposome-encapsulated fish oil and observed an increase in volume by 5% of the microcapsules addition. These results are referring to the characteristics of the coating polymers and, specifically, to the surface-active properties of lecithin used as an emulsifier within the liposomal system, which would have determined the improvement in gas retention, bread volume, and dough stability. Akhtar et al. ^[16][34] and Takeungwongtrakul et al. ^[20][38] suggested that the hydrophilic nature of the colloidal molecules used as a coating material for PUFAs microencapsulation could influence bread volume. Specifically, functional bread developed with the inclusion of Himalayan walnut oil encapsulated into the soy protein isolate–maltodextrin–pectin complex in different percentages and was characterized by a higher specific volume compared with the control bread ^[16][34]. In this case, the volume increase could be ascribed to the formation of the polysaccharide–soy proteins complex in the functional dough that could hinder cell coalescing, promote the alveolar formation, and thus increase bread volume. This thesis was corroborated by Takeungwongtrakul et al. ^[20][38], whose study investigated the incorporation of microencapsulated shrimp oil, another PUFAs source, in bread samples. The authors reported that whey protein concentrate selected as wall material might strengthen the bread structure by interacting with the gluten network and promote hold gas retention more efficiently, thus increasing the final volume. In contrast, Costa de Conto et al. ^[21][39] fortified bread with an increasing amount of commercial omega-3 and rosemary extracts microcapsules and observed a decrease in the specific volume that was inversely correlated with the microcapsules addition. The authors explained that microcapsules incorporation could dilute the gluten and interfere with the retention of gases, resulting in less volume. Similarly, bread with chia oil microencapsulated in soy protein isolate and maltodextrin showed a lower specific volume than bread with free oil. However, no significant differences between the bread fortified with microencapsulated oil and the control sample (without the oil) were reported. The non-encapsulated oil plasticizes and lubricates the gluten polymers of the dough, increasing dough rise and loaf volume. In addition, the inclusion of microencapsulated chia oil in bread determines a lower cell average area than other samples, increasing crumb uniformity ^[14][32]. The variation in the specific volume of loaves is linked to the bread’s textural properties, hardness, cohesiveness, and springiness, which are qualitative parameters that determine the texture of the bread. In general, it is desirable to have low hardness values in bread. That is what has been obtained by Akhatar et al. ^[16][34], which fortified bread with encapsulated Himalayan walnut oil obtained through a complex coacervation technique and observed a crumb hardness decrease (by up to 65%). The hydrophilic nature of pectin used as a wall material with soy protein isolate and maltodextrin increased the water-holding capacity and moisture in functional samples, thus reducing their hardness. A similar trend was observed by Takeungwongtrakul et al. ^[20][38] using whey protein concentrate as the coating material. The hardness reduction was also detected during the storage of bread fortified with microencapsulated garlic oil ^[17][35]. The hardness reduction may be due to the hydrophilic nature of the alginate used as shell material for garlic oil, which helped the retention of moisture. Similarly, the hardness reduction in bread fortified with liposome encapsulated-fish oil has been reported ^[19][37]. This would be due to the presence of lecithin and glycerol emulsifiers in the liposomal encapsulated structure. Contrarily, another study included the subsequent addition (from 0% to 5%) of commercial microencapsulated omega-3 fatty acids and rosemary extract in bread, which caused a linear hardness increase ^[21][39]. However,  to the best of our knowledge, the wall material(s) used in this work have not been reported.

Generally, the modification of the technological and rheological characteristics of bread fortified with microencapsulated bioactive compounds proceeds side-by-side with the variation of the sensorial aspects. The addition of fish oil nano-liposomal capsules in bread samples improved the crumb color, aroma, taste, and overall acceptability, resembling the values of the control sample ^[19][37]. Similarly, garlic oil microcapsules in bread enhanced all of the sensory parameters compared with bread with free garlic oil after a week of storage, presumably due to the lower oxidation rate of garlic oil within the microcapsules ^[17][35]. Similarly, the improvement of the sensorial characteristics and the bread acceptability was also reported during 7 days of storage with samples fortified with a blend of oils ^[17][18][35,36]. However, these positive effects on the sensory characteristics of bread fortified with a microencapsulated source of PUFAs appear to be dependent on the concentration of microcapsules used.

Hasani et al. ^[23][41] reported how the microencapsulation of fish oil could balance the fishy flavor and odor of fortified bread, highlighting a reduction in the taste, aroma, and overall acceptability of bread fortified with 5% of microencapsulated fish oil. Instead, there were no significant differences between the control sample and the one containing 1% microcapsules with respect to appearance, texture, and crumb. Likewise, Takeungwongtrakul et al. ^[20][38] reported the need to balance the amount of microcapsules used for bread fortification with oil rich in PUFA. The authors specifically reported that a 5% inclusion of shrimp oil microencapsulated using whey protein concentrate, sodium caseinate and glucose syrup caused a reduction in the odor, appearance, and overall likeness scores of bread.

Much research has been devoted to the encapsulation of plant extracts to be added into bread to improve the nutritional value, structural properties, and microbial stability of this product (Table 34). Specifically, when considering the incorporation of polyphenols, the encapsulation technique represents a valid solution to overcome their sensibility to high processing temperatures and alkaline pH as well as the possible undesirable increase in astringency and bitterness in the fortified products. Bread antioxidant properties and the content of phenolic compounds have been enhanced using extracts derived from several sources, such as Garcinia cowa fruit ^[24][25][10,42], green tea ^[26][43], Saskatoon berry fruit ^[27][28][44,45], and the bark of soybeans, onion husks, and young hawthorn shoots ^[29][46].

To date, the research carried out has never investigated the effects of bread fortified with microencapsulated carotenoids on the rheological and sensory characteristics. The main information reported is related to the increase in the bioactive compounds in bread, the controlled release of carotenoids, and the enhancement of the antifungal properties of the fortified bread. Working with pure β-carotene/soybean oil mixture and palm oil as core materials, Rutz et al. ^[30][49] tested, for analytical purposes, the use of complex coacervation and ionic gelation methods for preparing microcapsules using chitosan/carboxymethylcellulose as wall materials in the former method and chitosan/sodium tripolyphosphate in the latter. The results showed high encapsulation efficiency for both methods used and higher carotenoid content in microcapsules containing palm oil compared with those with b-carotene/soybean oil mixture. In a subsequent study ^[31][50], using palm oil as the core material and using the complex coacervation method, the authors tested the use of different core materials (chitosan/xanthan and chitosan/pectin) and different final steps of encapsulation (lyophilization and atomization). The lyophilized microparticles showed a higher yield and encapsulation efficiency and lower losses in carotenoids than atomized microparticles, but irregular shape and size were observed. When applied to bread, the chitosan/xanthan microparticles led to better releases of carotenoids, and the released compounds were not degraded. Pinilla et al. ^[32][51] reported that the use of phosphatidylcholine–oleic acid liposomes for encapsulating garlic extract in wheat bread led to a general enhancement of the antifungal properties of the product because of their high ability to protect the antifungal compounds of garlic from thermal degradation. The encapsulation efficiency was about 80% and the prevention of mold spoilage for wheat bread was documented, with only four and two slides of the bread being moldy at day fifteen of storage, respectively, for samples with free and encapsulated garlic extract; concerning the control samples, they were totally covered by molds in eleven days. Another result of interest is the role performed by the oleic acid in giving the liposomes higher thermal stability compared with pure phosphatidylcholine liposomes.

Probiotics are beneficial microorganisms that, if present in an adequate amount, has a variety of health benefits, including regulating the microbial flora of the gastrointestinal tract, preventing the growth of pathogenic microorganisms, and controlling the body’s immune responses ^[33][52]. Probiotic bacteria can also prevent cardiovascular disease and lower blood cholesterol. Bread is an innovative area in the probiotic food sector and has attracted increasing interest in research. Due to the high temperatures during the bread-baking process, the inclusion of probiotics in bread is challenging. Fortification of bread with free probiotic cells has been little investigated as the microorganism’s survival levels after baking remain low. On the other hand, microencapsulation appears to be a promising solution to overcome these hurdles; however, even now, this has not been extensively explored ^[34][53]. Before incorporating microencapsulated probiotics in bread, a characterization of them is essential for evaluating the encapsulation efficiency and resistance to the gastrointestinal environment (Table 45). In most of the research carried out, the encapsulated probiotics are evaluated by undergoing strong acidic treatment and high temperature to explore the resistance of the microcapsule to simulate the acidic environment of the stomach, or baking condition, respectively. Due to the intrinsic different resistance of the diverse probiotics, specific microencapsulation process optimization must be evaluated from time to time. Proof that there is not a valid encapsulation method to be indiscriminately used for all microorganisms is largely reported in the literature ^{[35][36][37][38][39][40][41]}[14,54,55,56,57,58,59].

Breadmaking involves the use of enzymes deriving from three sources: endogenous enzymes naturally occurring in flour, enzymes related to the metabolic activity of yeasts, and other dominant microorganisms and exogenous enzymes, which are intentionally incorporated in the dough ^[44][63]. The extensive use of exogenous enzymes has gained much importance due to restrictions in the addition of synthetic additives. Indeed, enzymes can act as flour standardizer, dough rheology modifiers, and improvers of textural properties and can be incorporated individually or in combination, encapsulated or not. Among the class of enzymes implied in baking, the endo-acting α-amylases are commonly used for their role in retarding staling and improving and/or standardizing flour (Table 56). The anti-staling efficiency relies upon the ability to limit the formation and the strength of the amylopectin network and act for water immobilization. In the work of Haghighat-Kharazi et al. ^[45][13] α-amylase derived from Bacillus licheniformis was encapsulated in beeswax to assess the effect in gluten-free bread, for which the staling represents a major issue. The catalytic efficiency was about two-fold lower and the thermal and storage stability were higher compared with the free-added enzyme. Furthermore, gluten-free bread with encapsulated α-amylase resulted in having a lower hardness and chewiness and higher sensory acceptability. Further research led to the investigation of the addition of maltogenic amylase derived from Bacillus stearothermophilus, as this exo-acting enzyme was discovered to be one of the most effective anti-staling amylases ^[45][13]. The authors tested the encapsulation of maltogenic amylase in low- and high-dextrose equivalent maltodextrins. Once incorporated into gluten-free bread, the different formulations showed no significant differences in moisture content and firmness parameters. Moreover, the higher softness of the crumb concerning the control samples was observed. In addition, bread with the low-dextrose equivalent maltodextrin had a higher uniformity of gas cells and lower weight loss. Afterwards, the use of beeswax, alone or with maltodextrin as the wall materials, for encapsulating maltogenic amylase in gluten-free bread was investigated ^[46][47][64,65]. Gluten-free bread with maltogenic amylase encapsulated with both beeswax alone or combined with maltodextrin showed an overall higher quality and sensory acceptability compared with the control samples. Furthermore, bread with the encapsulated enzyme was compared with the non-encapsulated one. The results showed a higher softness of the crumb for the bread with unencapsulated enzyme, but a higher sensorial acceptability for the one with microcapsules for up to 4 days of storage.

Glucose oxidase is another enzyme widely used in baking products for its antimicrobial properties because of its ability to remove glucose and oxygen residuals, producing hydrogen peroxide. However, the application in bread presents some drawbacks due to its low stability in dough and rapid oxidation. In this context, Zhang et al. ^[48][66] tested the use of encapsulation as a tool to protect glucose oxidase when added to Chinese steamed bread. The results showed that bread with microencapsulated enzyme had a slower action in catalyzing the oxidation of dough, resulting in higher extensibility and wet gluten content of the dough, better texture properties, and higher sensory acceptability.

Within the frame of improving the sensory attributes of cheese bread, Silva et al. ^[50][68] proposed the addition of microencapsulated Swiss cheese bioaroma in cheese bread. The spray-dried microcapsules were obtained using maltodextrin and corn starch in a ratio of 1:1, and 4 formulations of bread were prepared with 0.0, 2.2, 4.4, and 6.6% of the encapsulated cheese bioaroma. Regarding the structural and technical quality parameters, in treated samples the texture improved with increasing concentrations of the bioaroma because of the presence of modified starch and maltodextrin. Furthermore, the sensory acceptability indicated that the bread with 6.6% of encapsulated bioaroma was the preferred formulation, thus suggesting that the additive used gives a distinctive aroma to the cheese bread without (undesirably) affecting the structural and other sensory attributes of the product.