Quality, physicochemical, and textural properties of dairy products containing fruits and vegetables: A review

Abstract Due to the high utilization rate of dairy products, enrichment of these products will successfully decrease or prevent diseases related with nutrition deficiencies. Fruits and vegetables in different forms (i.e., fresh, juices, powder, puree, and extract) are excellent sources for the enrichment of dairy products because of their desired taste, color, aroma, fibers, and vitamins content. So, this manuscript reviews the effect of some fruits and vegetables on the rheological behavior, physicochemical attributes, color parameters, sensorial and quality properties of dairy products including cheeses, ice creams, and yogurts. The physicochemical, color, texture, and sensorial properties of dairy products were affected with addition of fruits or vegetables. Also, the addition of these products contributes to the higher content of vitamins, natural colorants, minerals, polyphenols, crude fiber, and carotenoids. In addition, some fruits and vegetables are considered as potential dairy products stabilizing agent due to their desirable functional properties, such as water binding and holding, gelling and thickening ability. In summary, enrichment of cheeses, ice creams, and yogurts with fruits and vegetables increase the market share of these products due to the high demand for goods for an improved diet, rich in compounds with antioxidant activity and biological properties.

| 4667 SALEHI to improving the health benefits of food products (Salehi, 2020f;Salehi & Aghajanzadeh, 2020;Satorabi et al., 2021). Addition of these products or their by-products in dairy products including yogurts, ice creams, and cheeses has been studied (Dibazar et al., 2016;Granato et al., 2018;Hashemi Gahruie et al., 2015;Jeong et al., 2017;Sah et al., 2016;. Figure 1 shows the schematic of some fruits and vegetables used for the formulation of cheeses, ice creams, and yogurts. For example, spinach powder, persimmon puree, and carrot juice could be used to improving the nutritional value and quality of cheese, ice cream, and yogurt, respectively.
The effect of fruits and vegetables on different characteristics of some dairy products is reported in Table 1. Data listed in this table show the physicochemical attributes of cheeses, ice creams, and yogurts containing fruits and vegetables powder. In summary, enrichment of cheeses, ice creams, and yogurts with fruits and vegetables provides functional dairy products with high nutritional values and acceptability.
Due to the high utilization rate of dairy products, enrichment of these products will successfully decrease or prevent diseases related with nutrition deficiencies (Gebreyowhans et al., 2019). Dairy products are rich in protein, fatty acids, calcium, potassium, B vitamins but are deficient in iron, vitamin C, carotenes, and dietary fibers (Caleja et al., 2016;Carocho et al., 2015;Hashemi Gahruie et al., 2015). Thus, the combination of fruits and vegetables products and by-products and cheeses, ice creams, and yogurts will improve the nutritional and functional food characteristics of these products.
Vitamins, polyphenols, and carotenoids are considered the most natural antioxidant molecules in fruits and vegetables. These natural compounds can provide better sensory, nutrition, and antioxidant quality compared to the artificial additives in dairy products (Caleja et al., 2016).
Fruits and vegetables products could be used to enhance the fiber content of dairy products. The diet with a high amount of fibers is reported to have an encouraging influence on health (Salehi & Aghajanzadeh, 2020). The significance of food fibers has led to the improvement of a high and potential market for fiber-rich products and components. Newly, there are trends to find a new source of dietary fibers that could be used in the dairy products. Fruits and vegetables fibers have better quality due to higher total and soluble fiber and water content and oil holding capacity and colonic ferment ability, in addition to lower phytic acid content and caloric value (Issar et al., 2017;Salehi, 2017). Also, the primary dietary source of phenolic compounds is present in fruits and vegetables products. It has been suggested that these products extracts, juices, and powders have the potential to be applied as functional ingredients in dairy products (Coïsson et al., 2005;Karaaslan et al., 2011;Salehi, 2020d;Wallace & Giusti, 2008).
Food enrichment is one of the most important processes for the enhancement of the nutritional quality and quantity in food products. Currently, the development of new dairy products formulations that are highly enjoyed by consumers is one of the driving forces of dairy industries. Fruits and vegetables are rich sources of total phenol, antioxidant, carotenes, minerals, and dietary fiber, and could enrich dairy products with these compounds. Fortified cheeses, ice creams, and yogurts appeal to a wide range of consumers and have the potential to enhance sales in the dairy industry. So, the present study summarized the effect of some fruits and vegetables includes apple, broccoli, carrot, grape, grapefruit, kiwifruit, orange, persimmon, pineapple, pumpkin, spinach, strawberry, and tomato on the physicochemical, color, textural, and sensorial properties and quality of dairy products, including cheeses, ice creams, and yogurts.

| CHEE S E
Cheese is one of the mainly popular dairy products, that is a rich source of necessary nutrients such as vitamins, amino acids, and minerals (López-Expósito et al., 2012). Also, consumers worldwide demand the development of cheese with reduced levels of synthetic additives, such as flavoring and coloring agents. In this section, I listed a plethora of applications of fruits and vegetables products in cheeses. Some researchers have studied the enrichment of cheeses by different nutrients and various sources of dietary fibers (El-Sayed, 2020; Mohamed et al., 2016). The physicochemical F I G U R E 1 Schematic of fruits and vegetables used for the formulation of dairy products 20% All broccoli-cheese powder blended samples contained more total polyphenols as compared to the plain conventional cheese powder.

1.6%
With addition of grape pomace powders to the cheeses formulation, antioxidant activity and phenolic content in all enriched samples were increased. Marchiani et al., (2016) Cheese Sesame 1%, 3% and 5%

3%
The cheese product was found to have the best sensory characteristics at the 3% sesame seed dose compared with the doses of 1% and 5%. Slozhenkina et al., (2019) Cheese (UF-Soft) Spinach powder 0.5%, 1%, 1.5%, and 2% 0.5% and 1% The total solid, protein contents, and acidity of cheese samples were increased considerably with the increasing of spinach nano-powder concentration.

49%
The ice creams kept the polyphenols and vitamin C contents in addition the natural color flavor of the kiwifruit added. -Waterhouse et al., (2013) Ice cream

Sun
Orange byproducts fiber 0.74% 0.74% Orange by-products fiber proved to be a promising alternative as a fat replacer in ice cream production.

24%
Better melting characteristics and texture parameters were reported for the ice creams containing different concentrations of persimmon puree. Karaman et al., (2014) Ice cream Quince seed powder 0%, 0.25%, 0.5%, and 0.75% 0.75% The adding of quince seed powder improved the protein content compared with the control samples due to the high protein content of quince seed powder (35%). The fortification of ice cream with quince seed powder can make an effective way to improve the nutritional and structural properties of ice creams.

25%
In strawberry ice cream-type frozen yogurt, the structure hardened in parallel with the enhancement in strawberry percent. Guven and Karaca, (2002) Ice cream

1.16%
Pineapple peel powder addition to yogurt lowered firmness and storage modulus. Syneresis level in probiotic yogurt with pineapple peel powder (1.2% at day 1) was comparable with the prebiotic-inulin and increased during storage.

1%
Pumpkin fiber could improve the physical quality and contributed to textural characteristics of half-fat yogurt.

30%
The addition 30% of strawberry cryoconcentrates resulted in a product with higher anthocyanins content and antioxidant activity.

Gasparrini et al., (2017)
Yogurt Strawberry 10%-20% -The addition of strawberry pieces to yogurt can decrease free polyphenols and whey protein contents, possibly constraining its bioaccessibility in yogurt.

1% 1%
Incorporation of the yam soluble fiber significantly decreased the syneresis. It produced a more acceptable mouthfeel in the fortified yogurt in comparison to the control samples, indicating the viability of the process to obtain a marketable product.    Table 2.

Ramirez
It is important to note that nutritional value, safety (microbiological and toxicological), and sensory properties should be taken into consideration when cheese added with fruits and vegetables products is manufactured. As shown in Table 1, the effect of carrot paste (Bandyopadhyay et al., 2008;Mohamed et al., 2016), broccoli (Sharma et al., 2011), grape extracts ( and observed that the combined cheese powder containing up to 20% broccoli powder was a suitable product and total antioxidant capacity, polyphenols, and carotenoids of broccoli-cheese were increased by increasing the broccoli powder concentration. In another study, El-Sayed (2020) studied the effect of spinach nano-powder (0.5%-2%) addition on the quality of ultra-filtered soft cheeses. The author demonstrated that by increasing of spinach powder concentration with retentate, the content of fibers, minerals, total phenolic content, and antioxidant activity of samples was enhanced.
Carrot is a rich source of vitamins (thiamine, riboflavin, and vitamin B-complex), minerals, and β-carotene (Salehi, 2018;Salehi et al., 2016). Since carrot is a valuable micronutrient source, so, it could be used in dairy products to enhance vitamin A and mineral contents. Bandyopadhyay et al., (2008)  of an analog processed spreadable cheese made with different concentrations (5%-15%) of carrot paste. The additions of carrot pastes improved the antioxidant activity and increased the nutritional components, vitamin A, carotenoids, and phenolic compounds.
Lycopene is a naturally occurring carotenoid in the tomato prod- Soxhlet-Henkel degree (°SH).

TA B L E 2 (Continued)
the production of Queso Blanco cheese, and these supplements will benefit the dairy industry and customer's health. Also, the textural properties of Queso Blanco cheese improved after fortification with the powdered microcapsules.  (Khorshidian et al., 2018). Potential utilize of passion fruit (PF) as a biopreservative in the making of coalho cheese was studied (Costa et al., 2020). The results indicated the inhibitory of PF and its potential use for controlling microbial populations in cheeses.
Different studies emphasize that fruits and vegetables byproducts can be a rich source of carotenoids, fibers, polyphenols, tocopherols, vitamins, and bioactive compounds (Salehi, 2020b, c). Generally, the use of these by-products in dairy can improve (from whole grape, grape seed, and grape skin) on the cheese-making characteristics of milk. With whole grape or grape seed extracts were added to milk at 0.1%, the recovery coefficient for polyphenols was about 0.63 and reduced with increasing extract levels in milk.
Also, the addition of grape extracts in milk slightly improved protein recovery in cheeses. In another study, Costa et al., (2018) examined the effect of powders from different by-products addition (red and white wine grape pomace, tomato peel, broccoli, and artichokes byproducts), at two concentrations of 5% and 10%, on the sensorial and physicochemical properties of Primosale cheese. The authors reported that the addition of these by-products to Primosale cheese enhanced the nutritional attributes and some sensorial properties

| I CE CRE AM
Ice cream, a sweet dairy product including milk, sweetener, stabilizer, emulsifier, and flavoring, is produced by mixing its ingredients, followed by pasteurization and homogenization. Afterward, it is aged at low temperature and finally frozen. Some parameters including rich sweet flavor, smooth and good texture, and cold sensation make ice cream a favored product of most people (Bahramparvar et al., 2014;Bahram-Parvar et al., 2017;Karaman et al., 2014).
Fruits and vegetables are excellent sources for the enrichment of food products because of their sweet and desired taste, color, and aroma (Salehi, 2020a, e). Many studies are reported in the literature about the development of new formulations of ice cream containing fruits and vegetables products. As shown in Table 1, the effect of cape gooseberry (Erkaya et al., 2012), carotenoids (extracted from tomato peel) (Rizk et al., 2014), citrus fiber (Dervisoglu & Yazici, 2006), hazelnut flour ( and hazelnut kernel skin (Dervisoglu, 2006), kiwifruit  , 2017). Fortification of ice cream with persimmon (puree or juice) can improve the quality of the ice creams in terms of nutritional, textural, physicochemical, sensorial, and bioactive (antiradical activity and total phenol) properties. In the Karaman et al., (2014) study, persimmon puree was added into the ice cream mix at various levels (8%-40%) and some physicochemical, textural, bioactive, and sensory characteristics of samples were measured. The authors reported that the dry matter, total ash, fat content, protein content, and apparent viscosity of ice creams were decreased with increasing persimmon puree concentration. Also, the glucose, fructose, sucrose, and lactose were characterized to be significant sugars in the ice cream samples, including persimmon and an increase in persimmon puree percent improved the fructose and glucose content.

Enrichment of ice cream with different sources of dietary fibers
and phenolic compounds has been the topic of some researches Understanding fat, proteins, and saliva impact on aroma release from flavored ice creams was studied by Ayed et al., (2018). At low fat level more aroma compounds were released from ice creams with lower protein content. The color parameters, textural properties, and apparent viscosity of some dairy products containing fruits and vegetables are summarized in Table 3. The addition of orange and apple dietary fibers decreased the lightness (L*) value, whereas the ice cream samples with wheat, oat, and bamboo did not considerably vary from the control sample in terms of that L*. Also, the presence of apple and orange fibers improved the red and yellow colors of the ice cream, resulting in increasing in the values of a* (redness) and b* (yellowness), respectively (Akalın et al., 2018). Orange fibers were used as a new fat replacer in light lemon ice cream (Crizel et al., 2014). The ice cream samples supplemented with orange fiber had considerably lower L* values and higher a* and b* coordinate values, indicating that the use of these fibers resulted in a product that was less bright and more red and yellow than the others. In addition, the orange fiber decreased about 50% in ice cream fat content and it increased fiber content and some textural characteristics values (firmness, gumminess and springiness), but it did not influence the adhesiveness and odor of the ice cream samples. The total acceptance of the ice cream with 1% of pretreated orange peel fiber did not vary from that of the control sample (80%).
Cape gooseberry is an exotic fruit that attracts great attention because of its nutritional and functional characteristics. It is characterized by plentiful amounts of essential minerals, polyphenols, vitamin C, vitamin A, vitamin B-complexes, minerals, tocopherol, and carotenoid (Bravo & Osorio, 2016). The effect of cape gooseberry addition at various levels (5%-15%) on the physicochemical and sensory characteristics and mineral content of ice cream was studied (Erkaya et al., 2012).

| YO G U RT
Yogurt is a fermented dairy product obtained by lactic acid fermentation during the action of Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus. The resulting lactic acid reacts with milk protein, promoting the characteristic textural and sensorial properties of this product (Serafeimidou et al., 2013). Also, yogurt is rich in protein, fat, calcium, potassium, B vitamins (B 1 , B 2 , B 6 , nicotinic and pantothenic acids) (Hanson & Metzger, 2010;Hashemi Gahruie et al., 2015). Some fruits and vegetables powders have been considered as potential yogurt stabilizing agents due to their desirable functional characteristics, including water binding, gelling, and thickening ability. For example, addition of yam soluble fiber to stirred-type yogurt increased the apparent viscosity of products and decreased the syneresis of yogurt and produced a suitable mouth feel date fiber (Hashim et al., 2009), apple, wheat, bamboo and inulin fibers (Staffolo et al., 2004), carrot juice (Cliff et al., 2013), orange fiber (García-Pérez et al., 2005), and pineapple peel and pomace powders (Sah et al., 2016) confirmed to improve the structure and decrease the syneresis of yogurts. Sensory quality and acceptability of dairy products fortified with fruits or vegetables were reported in Table 4.
The effect of date fiber on the quality properties and consumer acceptance of fortified yogurt was studied by Hashim et al., (2009).
The authors reported that yogurt incorporated with up to 3 g of date dietary fiber per 100 g of yogurt had similar sourness, sweetness, firmness, smoothness, and total acceptance ratings as the control

TA B L E 3 Textural and rheological properties, and color parameters of dairy products containing fruits or vegetables
Dairy product yogurt (without added dietary fiber). Still, that sensory ratings and acceptability of yogurt reduced significantly when increasing dietary fiber to 4.5%. In another study, apple pomace extract was used to create a fiber-enriched acidophilus yogurt, that demonstrated satisfactory sensorial qualities (Issar et al., 2017). The addition of apple pomace as a functional ingredient in yogurt and yogurt drinks was investigated by Wang et al., (2020). Apple pomace added to a diluted yogurt system has the potential to stabilize the acid drink and reduce the sedimentation of protein aggregates. Also, this study demonstrated that apple pomace has potential as a natural stabilizer as well as a dietary fibers source in yogurts and yogurt drinks.
The effect of pumpkin fiber (0.5%, 1.0%, and 1.5%) on physicochem-  yoghurts namely control, pumpkin, carrot, green pea, and zucchini were produced by Yildiz and Ozcan (2019). They reported that vegetable puree supplementation affected the pH, titratable acidity, syneresis, color, texture, and sensorial properties of the yoghurts. Also, firmness, consistency, and viscosity indices were higher in the yoghurt produced with carrot puree, whereas the highest antioxidant capacity was detected in the pumpkin yoghurt, which corresponded to the highest total phenolic, ascorbic acid, and total carotenoid contents.
Carrot is rich in β-carotene and bears ascorbic acid, thiamine, riboflavin, vitamin B-complex, tocopherol and it is classified as vitaminized food. It also carries carbohydrates and minerals including calcium, phosphorus, iron, potassium, magnesium, copper, manganese, sulfur, and phenolic compounds (Salehi, 2018;Salehi et al., 2016). Thus, the combination of carrot (juices or by-products) and yogurt will improve the nutritional and functional food characteristics of the yogurt (Fan & Cliff, 2017;Puvanenthiran et al., 2014). Salwa et al., (2004) have examined the effect of the carrot juice blending ratio on the shelf life and sensorial properties of yogurt and reported that shelf life and panelist acceptance were improved with a 15% carrot juice addition. In another study, Kiros et al., (2016) have studied the effect of carrot juice (0%, 10%, 15%, and 20%) and gelatin stabilizer (0.5%, 0.6%, and 0.7%) on the physicochemical and microbiological characteristics of yogurt. The authors reported that yogurt with suppressed syneresis and improved nutritional and total carotenoids content can be processed from 10%-15% carrot juice and 0.7% stabilizer additions.
Strawberry yogurt is one of the most consumed because of the sensorial characteristics like flavor and color, in addition to the nutritional properties including the presence of bioactive compounds (such as vitamin C, β-carotene, anthocyanins, and phenolic compounds) (Ariza et al., 2016). The anthocyanin is the main phenolic compounds in strawberry. This compound shows antioxidant and anti-inflammatory characteristics, also a large variety of chemotherapeutic effects, avoiding the oxidative stress and improving the antioxidant defenses (Aaby et al., 2012;Gasparrini et al., 2017;Jaster et al., 2018). To enhance the functionality and antioxidant capacity of yogurt, some food ingredients such as strawberry were added to the yogurt by some researchers Hanson & Metzger, 2010;Janiaski et al., 2016;Lesme et al., 2020;Lovely & Meullenet, 2009;Oliveira et al., 2015;Silva et al., 2013;Tirloni et al., 2015). Improvement of antioxidant activity and physicochemical characteristics of yogurt supplemented with concentrated strawberry pulp (15% and 30%) was investigated by Jaster et al., (2018). The author reported that the addition of the cryoconcentrated strawberry pulp in the yogurt samples resulted in a product with 3-fold more anthocyanin content and antioxidant activity. Therefore, the addition of strawberry to the yogurts formulation will improve antioxidant capacity, nutritional and functional food properties of the yogurts.
The intake of dietary fibers and the probiotics exerts a positive impact on the improvement of the intestinal microbiota and is reported to relieve constipation and decrease the incidence of colon cancer (Farnworth, 2008). Furthermore, epidemiological investigations No data available.

TA B L E 4 (Continued)
relate the impact of civilization-induced diseases to insufficient dietary fibers ingestion from fruits and vegetables (Nawirska & Kwaśniewska, 2005). Also, the beneficial effects on probiotics viability exerted by some ingredients such as fruits and vegetables pieces or pulp to dairy products have been examined (Espírito Santo et al., 2010;Kourkoutas et al., 2006;Sendra et al., 2008). Do Espírito Santo et al., (2012) investigated the effect of the supplementation of total dietary fiber from apple, banana, or passion fruit by-products on the acidity, bacteria counts, and fatty acid profiles in skim milk yogurts co-fermented by four different probiotics strains. Apple and banana fibers enhanced the probiotic viability during shelf-life. All the fibers enlarged the short-chain and polyunsaturated fatty acid contents of yogurts compared to their respective control samples in singular. Also, the effects of fruits and vegetables as a source of dietary fibers on the rheological behavior of yogurt have been examined, and showed stable physicochemical properties of fortified yogurt during storage (Sendra et al., 2010;Staffolo et al., 2004;Tseng & Zhao, 2013). In addition, some studies reported good stability of the bioactive compounds from grape and callus extracts in enriched yogurt (Karaaslan et al., 2011).

| CON CLUS ION
Dairy products such as cheeses, ice creams, and yogurts are consumed all over the world and the improvement of these products with vitamins, antioxidants, fibers, and polyphenols may be achieved through the integration of rich sources. The enrichment of dairy products with fruits and vegetables is an effective way to improve the nutritional aspect and to promote functionality by effect on the rheological behavior and physicochemical properties of the final product. In this review, the effects of some fruits and vegetables on the quality of dairy products such as cheeses, ice creams and yogurts have been presented. Fruits and vegetables addition influence the physicochemical and sensory properties of cheeses, ice creams, and yogurts. Some fruits and vegetables fibers proved to be promising food ingredients since they can be used to decrease the fat content and increase bioactive compounds content. Due to the nature of the fruits and vegetables fiber, functionally they hold such properties as increased water binding and holding, thickening, and gelling. Also, fibers from fruits and vegetables improve probiotics viability and increase conjugated fatty acids content in dairy products. Therefore, the fortification of dairy foods with fruits and vegetables could help to provide functional dairy products with high nutritional values and acceptability. Also, fruits and vegetables can be introduced to improve the appearance, color, and attractiveness of fortified cheeses, ice creams, and yogurts for consumers and to increase the sale of these products.

ACK N OWLED G EM ENTS
No financial support was received from any sources for this work.

CO N FLI C T O F I NTE R E S T
I declare that I do not have any conflict of interest.

E TH I C A L A PPROVA L
This study does not involve any human or animal testing.

I N FO R M E D CO N S E NT
Written informed consent was obtained from all study participants.
The manuscript is not submitted or under consideration in any other journal.

DATA AVA I L A B I L I T Y S TAT E M E N T
Data sharing is not applicable to this article as no new data were created or analyzed in this study.