WHEY-BASED BEVERAGES
DOI:10.30825/5.EJPAU.36.2017.20.4

Katarzyna Skryplonek, Małgorzata Jasińska
Department of Dairy Technology and Food Storage, Faculty of Food Sciences and Fisheries, West Pomeranian University of Technology, Szczecin, Poland

ABSTRACT

Whey is a by-product of dairy industry obtained during cheese and casein production. It contains approximately 93% of water. Main solid ingredients include lactose, whey proteins and mineral salts. Due to the characteristic taste, unprocessed whey is not an attractive product for consumers. However, the valuable composition of nutrients, as well as increasing demand for healthy food products, contributes to the development of accepted by consumers whey drinks. Until now a wide variety of whey beverages were developed. Among them can be distinguished unfermented and fermented beverages, probiotic beverages, refreshing soft drinks, alcoholic beverages, diet beverages, high-protein sport drinks and powder beverages. Manufacture of beverages is an important group of methods of whey management in food production. The aim of this article was to review the current literature related to the production of various types of whey-based beverages.

Key words: whey, beverages, new food products.

INTRODUCTION

Whey is a by-product obtained during cheese and casein production. It is a yellow-greenish liquid with sour slightly salty aftertaste. Cheese industry provides huge amounts of whey, which constitutes from 85 to 90% volume of milk used in the production. During the preparation of cheese, approximately 55% of the components of milk solids go to whey. These components are almost 100% of lactose, the bulk part of minerals, and approximately 20% of the milk proteins. The proteins consist of soluble whey proteins and only trace amounts of casein which forms cheese curd [38, 46]. Due to the method of milk coagulation, there are distinguished two types of whey. The first type is rennet (sweet) whey with the acidity in the range pH 6-7, which is obtained as a result of enzymatic milk coagulation performed with the use of chymosin enzyme. The second type of whey is acid whey with pH value below 5 which is a by-product of coagulation of milk by acidification [23]. Whey contains about 93% of water. The main components of rennet whey dry matter are lactose, proteins, mineral salts and negligible amounts of fat [38]. In comparison to rennet whey, acid whey contains smaller amounts of proteins and greater amount of mineral salts. It also consists of considerable amounts (0.6%) of lactic acid [3, 38]. The composition of rennet and acid whey is presented in Table 1.

Whey ingredients have high nutritional value and are easy digested and assimilated. Especially precious are whey proteins, which have the highest biological value among all proteins present in food, moreover they have a number of health-promoting effects. Additionally, whey is a rich source of minerals (calcium, phosphorus, sodium, potassium, chlorine, iron, copper, zinc, magnesium), as well as vitamins B [4, 21]. World production of whey is constantly increasing and according to Fox et al. [18] is estimated at about 2 ×108 tonnes per year. In connection with the constantly increasing amount of whey and its valuable properties, this raw material is widely used and has numerous applications in food production [32, 48]. Recently we can observe the development of plenty of new products containing whey or whey proteins. The aim of this article was to review the current literature related to the production of various types of whey-based beverages.

DEVELOPMENT OF WHEY BEVERAGES

New methods of whey utilization cause the increase of the profitability of processing of this raw material and contribute to the further development of applied technology [46]. Analyzing the latest trends in whey processing, it seems that one of a pivotal and perspective directions of whey management is beverages production. The use of whey as a beverage consumed especially for therapeutic purposes has been known since ancient times because of Hippocrates. Due to characteristic taste, unprocessed whey is rather perceived as unattractive product. Although beneficial composition of nutrients and growing demand for health promoting products contribute to the development of new, attractive from the consumers’ point of view, whey beverages.

So far a wide range of whey beverages has been developed .The beverages can be divided into few main groups which are: unfermented and fermented beverages, probiotic beverages, refreshing soft drinks, alcoholic beverages, diet beverages, high-protein sport drinks, beverages for direct consumption and powder beverages [6, 11, 24]. Apart from the beverages in which whey is main or major raw material there is also a large number of beverages containing ingredients derived from whey, especially whey proteins. Whey protein concentrate (WPC), whey protein isolate (WPI) and whey protein hydrolysate (WPH) are frequent ingredients of high-protein drinks, mainly sport drinks and drinks for malnourished. An undesirable phenomenon in the case of beverages containing whey proteins is the turbidity and sediment formation [17, 29].

BEVERAGES WITH FRUITS AND VEGETABLES

Beverages with fruit juices can be produced from acid whey, which sour taste harmonizes with the taste of the fruit. Additionally, these beverages can be enriched with vitamins and minerals [24]. The study of Branger et al. [5] presented beverages from deproteinated whey obtained during cottage cheese production, combined in changed proportions with grapefruit juice. Other beverages with fresh fruit blends (oranges, pears, peaches and apples) with addition of citric acid and sucrose were developed by Djurić et al. [14]. The best product obtained in the study was a beverage with peach blend and 2% of sucrose. Shekilango et al. [42] developed product made of acid whey and banana pulp combined in a ratio of 3:2. Beverages based on acid whey with 10% addition of bananas, sucrose and mint extract as natural flavouring agent were the subject of studies of Yadav et al. [47]. The authors concluded that addition of edible herbal extract can enhance nutritional and sensory properties of whey and juice beverages. Similar product made of acid whey, banana juice (15 ml per 100 of beverage) mint extract and sucrose was developed by Dhamsaniya and Varshney [13]. Other whey beverages obtained from acid whey and mango pulp which were also flavoured with mint extract were presented in article of Sirohi et al. [45]. Study conducted by Sakhale et al. [40] concerned combination of whey with mango juice. They indicated that the best ratio of acid whey to mango juice was 7:3. Obtained products were characterised with good sensory quality and high ascorbic acid content. The beverages made of pasteurized rennet whey with 3% of sucrose and 15, 25 or 35% addition of fresh fruit (apple, pear, orange, grapefruit or kiwi pulp) were the subject of Siemianowski’s [44] study. Sady et al. [39] indicated that acid whey can be used in orange drink production. The substitution of 50% of water with acid whey caused higher level of protein, ash, glucose, lactose and vitamin B2. However drink containing whey had lower overall sensory evaluation in comparison to drinks without whey.

Whey and fruit beverages can be used as a carrier for probiotic bacteria. This kind of product were the subject of study conducted by Zoellner et al. [49]. The beverages containing 5% of acai pulp was enriched with two probiotic strains of Bifidobacterium longum and Lactobacillus acidophilus species. The results revealed, that the addition of acai pulp significantly increased the viability of probiotics. Also studies of Shukla et al. [43] concerned probiotic whey beverage development. The beverages consisted of acid whey and pineapple juice were enriched with probiotic strain of L. acidophilus. The combination of whey and pineapple juice proved to be a good medium for the probiotic strain, although the viability of bacteria slightly declined during refrigerated storage.

Moreover beverages based on whey combined with fruits can be enriched with minerals. Miglioranza et al. [33] obtained functional product which reduced the risk of anemia. Beverages with 15% of frozen strawberry were fortified with ferrous bisglycinate. The result showed that regular intake of the beverages prevented a deficiency of iron in the diet and increased the content of hemoglobin in the blood.

Beverages with fruits in order to improve the sensory properties and give more refreshing taste may be saturated with carbon dioxide and produced as fizzy drinks [11, 24].

Beside fruits, whey beverages may contain vegetables. Olkowski and Pluta [35] received beverages contained rennet or acid whey. Demineralised lactose free whey powders were dissolved it in water and combined with tomato concentrate. The result showed that both type of obtained products had good quality properties, although variant with rennet whey had higher sensory attractiveness.

OTHER UNFERMENTED WHEY BEVERAGES

Whey beverages can contain other natural ingredients that play the role of enhancing the nutritional and sensory features of product. These are mainly honey, vanilla and cocoa. Also bran can be considered as interesting ingredients of whey beverages due to high fibre, protein and minerals content which can distinctly enrich nutritional value of products [11, 24]. In order to obtain a product suitable for people with lactose intolerance, this disaccharide can be enzymatic hydrolyzed to monosaccharides glucose and galactose. Apart of easier digestion, these sugars have higher solubility and higher sweetness than lactose, what makes them natural sweetening agents [11, 24].

Other group of unfermented beverages based on whey are dairy-type beverages. In this group can distinguished products resembling milk, milk shakes or flavoured milk. These products can be a mixture of liquid or dried whey with such components as whole or skimmed milk, buttermilk, vegetable oils, hydrocolloids or emulsifiers [11].

Thirst quenching whey drinks are usually made of deproteinated whey. An excellent example of this type of product is Rivella produced in Switzerland. It is a drink developed and introduced to the market in the 50s of the twentieth century. By far, this is the biggest commercial success among produced on a large scale whey drinks. Rivella consists of water, whey (35%), sugar, lactic acid, caramel and natural flavorings and is saturated with carbon dioxide. Currently, there are several taste versions of this drink, as well as a low-calorie option with no sugar added [51].

Whey powder drinks have an important position among whey beverages. These instant products can be effortlessly prepared by dissolution in water. In order to improve solubility, spray dried whey usually undergo an agglomeration process. Powder drinks may contain flavouring and sweetening agents and may be enriched with vitamins and minerals. The advantages of beverages in powder form are their easier transportation and storage [24].

FERMENTED WHEY BEVERAGES

Whey as an abundant source of lactose, is a good environment for grow and survival of microorganism capable of enzyme β-galactosidase production, like lactic acid bacteria and some yeast. This enzyme enables microorganisms to use lactose as an easily accessible source of energy in fermentation process. Fermented dairy-type beverages are very popular among consumer and due to high nutritional and low energy value, these products are perceived as health promoting food. Awareness of the impact of diet on the health and condition is getting higher among consumers. Therefore, the consumption of this group of product is constantly growing. Consumers are willing to reach for new fermented dairy products and that trend results in dynamic development of this branch of dairy industry [19]. Fermented whey beverages are the group of products, in which the whey is fermented with species of microorganisms which produce enzyme β-galactosidase and are capable to lactose hydrolysis. The main group of these microorganisms are lactic acid bacteria, including probiotic strains of bacteria, which perform lactic acid fermentation of whey. Other type of fermented whey beverages undergo alcoholic fermentation involving yeast mainly of the genus Kluyveromyces or Saccharomyces or mixed fermentation with both lactic acid bacteria and yeast [11, 24].

Fermented whey beverages are significant group of whey-based drinks. Technology of their production is usually less complicated than the production of unfermented beverages, which often includes more steps and is more expensive. Due to lactic acid presence, fermented whey beverages have refreshing taste. Furthermore, low pH of fermented products prevents the growth of microorganisms responsible for spoilage, what significantly prolongs the shelf life of the beverages. Additional advantage of fermentation process is production of aroma-forming compounds affecting the rich aroma profile similar to the aroma of fermented milk drinks [19]. It is also found, that some strains of lactic acid bacteria are able to reduce the allergenicity of β-lactoglobulin, the major whey protein [26].

Fermented beverages containing probiotics are not only a source of nutrients but also a source of live microorganisms destined to promote a positive impact by improving the properties of the indigenous beneficial microbiota. It has been shown that probiotics enhance the immune system, reduce blood pressure and blood cholesterol as well as exhibit antitumor activity. Probiotic bacteria used in fermented whey beverages production include following species: Lactobacillus reuteri, L. acidophilus, Lactobacillus casei and Bifidobacterium sp. [22, 41, 50].

Fermented whey beverages were the subject of a large number of publications in recent years. Kar and Misra [25] produced beverage from deproteinised whey and yogurt bacteria cultures. The product had acceptable sensory quality and affected antibacterial activity thus was considered as potentially therapeutic.

Whey beverages with probiotic cultures of L. acidophilus, Bifidobacterium bifidum and L.  casei made of reconstituted rennet whey with 1% prebiotic inulin addition were investigated by Drgalić et al. [16]. They stated that drinks with Lactobacillus cultures had better sensory properties than drink with B. bifidum, which had poor taste and odour. The count of bacteria was higher than 107 cfu·mL^-1 during 4 week storage and inulin addition had an almost negligible effect on this quantity.

The research team of Gallardo-Escamilla et al. [20] also used yogurt cultures to conduct the fermentation of rennet whey with selected hydrocolloids addition (pectin, alginate, carboxymethylcellulose and xanthan). The results showed, that the best texture, similar to that of commercial fermented milk beverages, had products with carboxymethylcellulose and pectin, although the addition of hydrocolloids caused less intense aroma of the samples.

Probiotic beverages obtained by Hernandez-Mendoza et al. [22] from reconstituted rennet whey with sucrose and pectin fermented by mixed culture of L. reuteri and B. bifidum had count of both bacterial populations greater than 106 cfu·mL^-1 for the whole 30 day storage period. The products had good sensory quality, although their acidity increased during storage.

Pescuma et al. [37] evaluated the ability of selected strains of yogurt bacteria Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus combined with probiotic strain of L. acidophilus to grow in reconstituted rennet whey. Fermentation and proteolytic activity of the bacteria were high and the authors proved, that these microorganisms may be used for fermented whey beverages production. In subsequent paper, the same group of researches [38] prepared similar beverages, but based on WPC35 instead of whey. These products had lower content of lactose and higher concentration of essential amino acids than beverages made of whey, thus WPC may be used in functional beverages production.

The subject of another study [1] were products made of rennet whey and milk with yogurt bacteria and selected probiotic cultures (L. acidophilus, Lactobacillus rhamnosus, Bifidobacterium animalis). High acidifying capacity and viability of the bacteria suggested that they could be employed in whey-milk beverages manufacturing.

Milk-whey mixes contained from 30 to 42% of rennet whey with 1–5% addition of oligofructose were studied by de Castro et al. [12]. The fermentation were conduct by strains of S. thermophilus, L. acidophilus and Bifidobacterium spp. The researchers concluded, that whey concentration did not influence fermentation dynamics, however product with higher whey addition had higher syneresis index. Level of whey as well as oligofructose at the concentrations evaluated in that study, did not show any significant influence on the viability of tested microorganisms.

Probiotic fermented beverages from milk mixed with rennet whey in amount ranged from 0 to 80% were the subject of the study of Castro et al. [10]. The products were prepared with usage of yogurt cultures and probiotic culture of L. acidophilus and contained sugar and strawberry-flavored fruit preparation. All beverages presented high count of bacteria. Whey content had a significant effect on acceptance of the beverages. The increase of the whey content, caused more fragile gel structure, what was due to the  replacement of casein by whey proteins in the gel structure. The product formula with the most appropriate sensory characteristic had 49% concentration of whey.

Bulatović et al. [7] prepared beverages from reconstituted rennet whey with yoghurt bacteria and probiotic strain of Lactobacillus helveticus. They found, that the most appropriate temperature of fermentation process is 42°C. The beverage produced at this temperature achieved high cell viability and long storage stability with a shelf life of 22 days. The same scientists’ team [8] claimed that the viability of other probiotic bacteria strain Lactobacillus johnsonii can be improved by inulin addition. Furthermore, prebiotic properties of this compound improve nutritional value of the beverage. In another work [9] the authors made fermented whey beverage enriched with 30% of skim milk and probiotic strain of L. rhamnosus. The beverage contained also yogurt bacteria. The obtained whey-based product had desirable texture and sensory quality attributes and was similar to traditional milk products. The beverage contained high level of probiotic bacteria and its characteristic were stable during 20 day shelf life.

An example of probiotic whey beverage produced on a commercial scale is "Gefilus", which contains the strain of L. rhamnosus. This produced in Finland product is made from demineralized whey, in which the lactose is enzymatically hydrolysed. The beverage composition comprises fruit juices or flavors and sweeteners [24].

Apart from lactic acid bacteria, whey is considered as a good medium for growth of kefir cultures. Kefir microflora is a symbiotic association of microorganisms (Lactobacilli, Lactococci, Kluyveromyces, Candida etc.) which are embedded in a polysaccharide matrix (kefiran) and form kefir grains. This microflora is effective in lactose fermentation and has been used for the production of a kefir, refreshing fermented milk drink [2, 36].

A kefir-type drink prepared by fermentation of whey mixed with milk (20%) containing fructose and black raisin extract were evaluated by Paraskevopoulou et al. [36]. The beverages contained selected polysaccharides which were xanthan, guar gum and high methoxyl pectin. It was showed that the most effective stabilizer of the product was xanthan which required lower concentration level than other additives. Athanasiadis et al. [2] obtained similar kefir-type whey beverages from whey with fructose and black raisin extract. The work of Koutinas et al. [28] presents production of this beverage in industrial scale.

Other whey-based kefir beverages were developed by Magalháes et al. [30, 31]. They used as a substrate milk, whey or deproteinised whey. The results of this comparative studies revealed that activity of microorganism was similar in all mediums and whey may serve as the raw material for the production of kefir-type beverages similar to milk kefir.

ALCOHOLIC WHEY BEVERAGES

High content of disaccharide lactose makes whey relevant raw material for the production of alcoholic beverages. The production methodology is usually based on the fermentation of deproteinised whey with species of yeast capable to lactose fermentation like Kluyveromyces fragilis. The beverages may be fortified with sweetening and flavoring agents. An example of this type of beverages is prepared in Poland whey champagne "Serwovit". The whey can also be used for beer production. It may be combined with the wort in varying proportions or may be fermented alone [11, 24]. An example of beer whey is English brand "The Blue Brew", in which some of the wort is replaced by whey derived from the production of Stilton cheese [52].

Whey may be also used for wine-type beverage production. This kind of product is made of demineralised and deproteinised whey. In order to obtain higher ethanol concentration in final product, the whey may be enriched with sucrose or glucose. Subsequently, the substrate undergoes alcoholic fermentation process performed by lactose-fermenting yeast of the genus Saccharomyces and glucose and galactose fermenting Saccharomyces species. The final product has organoleptic properties similar to white wine [27, 34].

After the alcoholic fermentation whey may be subjected to a distillation process [34]. In the work of Dragone et al. [15] an alcoholic beverage (35.4% v/v ethanol) was produced by distillation of the fermented broth obtained by fermentation of deproteinised whey with yeast Kluyveromyces marxianus. The researchers concluded that volatile compounds in the product were similar to those reported for other alcoholic beverages. Therefore whey can be used for production of a novel spirit with acceptable sensory characteristics.

CONCLUSION

Whey is abundant by-product of dairy industry characterized by high nutritional value. Nowadays, there is observed a great development of technologies that employ whey as a raw material to food production. The usage of whey in human nutrition can be enhanced by production of whey-based beverages. Recent literature provides many examples of beverages with high nutritional quality and desirable sensory properties and some of them are produced on an industrial scale. Due to health benefits, whey-based beverages are often classified as food of new generation or functional food. The beverages production not only constitutes one of pivotal fields of whey management, but also it is a reasonable method for a broader inclusion of so rich in nutritional benefits by-product, into the consumers’ diet.

REFERENCES

Accepted for print: 26.12.2017

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