Today, most countries witness a profound shift in the structure of major causes of death and a growth in chronic disease, stress, and fatigue, with non-communi- cable diseases increasingly becoming most common in the 2st century.

One of them is metabolic syndrome (MS), also known as Reaven’s syndrome,  insulin resistance syn- drome, or atherothrombogenic syndrome. It is a complex metabolic disorder often found in patients with arterial hypertension and abdominal obesity. MS is linked to tissue insulin resistance that contributes to the develop- ment of hyperinsulinemia, activation of the sympatho- adrenal system, increased vascular tone and pathological changes in the lipid spectrum of blood [1].

The main risk factors for MS are hypodynamia, hy- percaloric  nutrition,  easily  available  pseudo-nutrition

with a low content of beneficial nutrients or antioxidants and an abundance of oxidation accelerators, increased activity of the sympathetic nervous system, and frequent stress. It explains why, with the last two factors exclu- ded, A. Regenauer (1998) called MS a ‘good life’ syn- drome, referring to a low-active lifestyle. Indeed, seve- ral studies show that a decrease in physical activity and a high carbohydrate diet are the main reasons why the in- cidence of MS is reaching epidemic proportions. About 25% of the population in Western countries suffer from this disorder [2].

According to the Institute of Nutrition of the Rus- sian Academy of Medical Sciences (www.ion.ru), more than a third of the Russian population are overweight or obese. At the same time, the consumption of confe- ctionery foods is growing due to their variety and af- fordability, as well as people’s stable taste preferences.

Copyright © 2019, Nikitin et al. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), allowing third parties to copy and redistribute the material in any medium or format and to remix, transform, and build upon the material for any purpose, even commercially, provided the original work is properly cited and states its license.

Yet, their physiological value is quite low: they are rich in fat (up to 40%) and carbohydrates (up to 70%) but lacking in vitamins and minerals [3].

The RF Government’s Order No. 1364-p of June 29, 2016 ‘The Strategy for Improving the Quality of Foods in the Russian Federation until 2030’ (www.government. ru) indicates a need to create conditions for the pro- duction of new generation foods with specified quality characteristics. They include specialised, functional, en- riched, and organic foods. To do this, we need research aiming to provide a biomedical rationale and develop new formulas and technologies.

Prevention of nutritional diseases is a social task that cannot be fulfilled by doctors alone. Great responsibility in addressing this issue rests with the food industry. It must ensure not only food safety but also optimal quality

– nutritional value, sensory properties, and health bene- fits – and its motto should be ‘The 21st century foods are health and taste!’ [4–8].

Thus, of scientific and practical interest is the de- velopment of technologies that can create confectionery products using non-conventional raw materials rich in essential substances [9, 10].

This study aims to develop a formula and a techno- logy for producing fruit jelly with an improved carbo- hydrate profile using non-conventional bio-raw material (red viburnum berries). We also intend to measure its an- tioxidant capacity and physicochemical and organoleptic characteristics.

The improvement of the carbohydrate profile implies a partial or complete replacement of mono- and disaccha- rides with ingredients having a low glycaemic index [11].

STUDY OBJECTS AND METHODS

The study was conducted by the Department of Grain Processing, Baking, Pasta and Confectionery Technologies at K.G. Razumovsky Moscow State Uni- versity of Technology and Management (the First Cos- sack University) in collaboration with the Information Technology Section at V.M. Gorbatov All-Russian Re- search Institute of Meat Industry and the Core Facili- ty ‘Industrial Biotechnology’ at the Federal Research Centre ‘Fundamentals of Biotechnology’ of the Russian Academy of Sciences.

We used red viburnum puree and citrus puree (grapefruit, orange, and lemon) were used as the main raw materials to produce test samples and develop the technology. The objects of the study were fruit jelly sam- ples with a different proportion of the main raw materi- als, namely 25:75, 75:25, 60:40, 40:60, and 50:50.

The control sample was made from apple puree ac- cording to the traditional recipe (Table 2) [12].

To prepare the test samples, red viburnum berries and citrus fruits were sieved to make a puree. Then, they were sieved again to  separate  the  puree  from any particles of peel or seeds that might be there af- ter the first rough sieve, as well as free it from any fo- reign matter. For this purpose, it was passed through an MPR-350M-01 (Belarus) pulping machine with a sieve

hole diameter of 0.5–1 mm.

Air-dry edible gelatin was soaked in a fourfold vo- lume of water at 20–25°C to swell for 40–60 min. The hydration of macromolecules and the destruction of bonds between them, which occurred during the swel- ling process, speeded up the dissolution of the gelling agents in water. The swollen gelatin was heated until it was completely dissolved, without bringing it to a boil, and then introduced, in a thin stream  and  with  con- stant stirring, into a fruit and berry syrup. The syrup was obtained by boiling-out red viburnum puree, citrus puree, and fructose syrup until a dry matter content of 67–69% was reached. The resulting mass was poured into silicone moulds and cooled for 1–2 hours to a tem- perature of 23–25°C. To form a structure, the jelly mass was cured for 2–3 hours at 23–25°C. Then the samples were removed from the moulds, sprinkled with starch, and dried for 10–12 hours until a crust formed. The crust protects the fruit jelly from getting wet and gives it an attractive appearance.

We tested such sensory characteristics as: taste; co- lour; aroma; consistency; grittiness; stickiness; and sur- face condition.

We also examined physicochemical characteristics of the samples, such as acidity, mass fraction of total mois- ture, glycaemic index, and antioxidant capacity (AOC). For that the following methods were used:

1. 1. 1. Acidity was determined by titration with phenol- phthalein.
      2. Mass fraction of total moisture was measured by drying on a VChM-A device (Ukraine) at 160–165°C for 3 min.
      3. Mass fraction of reducing substances was deter- mined by a method based on the recovery of an alkaline copper solution (hot titration method).
      4. The glycaemic index was determined as an amount of glucose accumulated during the product’s breakdown in vitro [13]. The sample was soaked in 0.1 N hydrochloric acid solution and put into a bath at 37°C. After a 10–15 minute incubation, a preparation of pro- teolytic enzymes (for example, Panzinorm) was added. Then the reaction mixture was neutralised with sodium bicarbonate to reach a pH of 8.2–8.5. A preparation of the duodenum of laboratory animals (e.g. rats) was ad- ded at the same time. Then the sample was incubated for another 1.5 hours at 37°C and filtered or centrifuged. The protein content was determined spectrophotometri- cally and the glucose content, by an enzymatic method.
      5. AOC was measured using an atomic spectro- photometer (Carry 100 Bio, USA). Its operation is based on determining the ratio of  two  light  fluxes that pass through the  reference  channel  and  the sample channel in the cuvette compartment. The spectrophotometer also uses the Stop-And-Go scan- ning principle (stopping the  diffraction  grating  for the  chopper  rotation  cycle).   Unlike   the   traditio- nal non-stop chopper rotation principle, it allows for adequate results without recalibrating the spectropho- tometer at any  scanning  speed,  up  to  3,000 nm/min in the UV-visible part and up to 8,000 nm/min in the near-IR part of the spectrum. Correct conditions for ana-

lysing the spectrum ensure valid analytical results. The

spectrophotometer measured the  AOE  of  the  lipophi- lic and hydrophilic fractions of the samples in relation to the radical cation of the 2-azinobis-3-ethyl benziazo- lite-6 sulfonic acid diammonium salt (ABTS).  Trolox was used as a standard in the AOC analysis and the re- sults were expressed in Trolox equivalents (TEq).

The tasting data were  processed  by  mathemati- cal statistics methods in Microsoft Excel. The experi- ments were repeated three times. A confidence level of

1. 95. was used to test the hypotheses. The consistency of expert opinions was determined by a coefficient of con- cordance, whose significance was checked with the chi- square test.

RESULTS AND DISCUSSION

The paper describes the main stages of improving the

carbohydrate profile of candied fruit jelly, in particular:

• justifying the selection of food ingredients with hypo- glycaemic effect;
• developing formulas of fruit jelly samples with an im- proved carbohydrate profile and testing technological pa- rameters of their production;
• optimising physicochemical and organoleptic charac- teristics of fruit jelly samples;
• determining the glycaemic index (GI) of fruit jelly samples; and
• studying the antioxidant capacity (AOC) of fruit jelly samples.

The control sample was apple jelly based on the clas- sic recipe and traditional technology.

• 1. 1. Justifying the use of red viburnum and orange as fruit jelly ingredients. The selection of fruit jelly in- gredients (see ‘Study Objects and Methods’) was based on the comprehensive approach to the development of enriched and specialised foods [14, 15]. This approach contains three groups of criteria, namely:
• biomedical;
• technological; and
• economic.

Medical and biological criteria cover the choice of enriched or specialised products and functional ingre- dients, setting the amount and restricting the content of specific substances and components, as well as their bio- availability and safety.

Technological criteria are concerned with the sim- plicity and ease of use of a specific ingredient, its ef- fect on the properties of semi-finished products and the quality of finished ones, its compatibility with the main components, and the method of introducing the ingre- dient into the formula.

Economic criteria are used to estimate the economic efficiency of an ingredient and its effect on the produc- tion cost.

Taking the above criteria into consideration when producing functional and specialised foods will enable us to find an optimal solution based on the technology of effective food functionality.

The plant raw materials used in the study is per- mitted in the production of sugary confectionery [16], including foods for children aged three and above, and

28

meets the safety requirements specified in the regulatory

documents*.

Red viburnum (Vibúrnum ópulus L.) is richer in vita- mins than many fruits, which makes this beneficial ingre- dient quite promising in fruit jelly production [17–20].

Due to its pectic substances, viburnum juice  can turn into jelly [21], which is essential in fruit jelly pro- duction. The percentage of P-active compounds (bio- flavonoids) in viburnum berries and juice can reach 300–500 mg/100 g. Viburnum contains vitamins A, D, and E. Interestingly, it has a higher content of vitamin C than citrus fruits. Viburnum is also rich in minerals, such as phosphorus, magnesium, potassium, iron, cal- cium, copper, manganese, and iodine (Table 1). These berries have plenty of invert sugar (about 30%), tannins, as well as isovaleric and acetic acids [22, 23]. Viburnum seeds contain up to 21% of fatty oil. Isovalerianic acid esters and viburnin glycoside, a natural substance of the cardiovascular and antispasmodic group, give viburnum berries their characteristic smell and bitterness. Despite its beneficial properties, viburnin had a strong negative impact on the sensory indicators of fruit jelly quality. Jelly had an off-odour, so a need arose to eliminate or disguise it in the finished product. The main solutions to this problem were heating, which partially destroys this glycoside, and using strong flavours of natural origin, such as citrus, to neutralise the smell [24].

Citrus fruits have a high biological value due to a va- riety of biologically active substances. Thus, flavonoids help the body to absorb vitamins, pectic substances protect the cardiovascular system, glycosides (such as naringin) lower blood pressure and cholesterol level, pre- venting heart attack and acting as a tonic [25].

After testing lemon,  orange  and  grapefruit  puree as possible components of viburnum jelly formula that could neutralise the smell of viburnin, orange was se- lected as the cheapest alternative. Then, we analysed the sensory characteristics (taste, aroma, texture, stickiness, and surface condition) of the test samples made from the above citrus fruits and viburnum puree in a ratio of 75:25 to 25:75. The analysis showed that the fruits only changed the colour and the taste of the finished product and had almost no effect on the other indicators that are essential in the fruit jelly technology.

Orange puree is rich in B vitamins, ascorbic acid, macro-  and  microelements  (Table  1),  and  fibre.  It  is a valuable source of amino  acids  and  contains  over 170 phytonutrients and 60 flavonoids.

Pectin contained in viburnum puree is not enough to form a strong jelly, therefore gelatin was used as an ad- ditional gelling agent.

Gelatin is widely used in the food industry due to its unique structure-forming properties. It gives confection- ery a stretchy, jelly-like or foamy texture and has an abi- lity to bind water and stabilise dispersed systems. Pro- teins make over 85% of gelatin composition, with col- lagen being the main component. This product contains two essential amino acids, hydroxyproline and proline.

* SanPiN [Sanitary Rules and Norms] 2.3.2.1940-05, Technical Regu- lations of the Customs Union 029.

Table 1. Chemical composition of red viburnum and orange [26, 27]

Fats, g                            1.50                           0.20

Carbohydrates, g            7.00                           8.10

Energy value, kcal        26.30                          43.00

Vitamins

Vitamin A, mcg              25.00                         8.00

Vitamin C, mg               82.00                         60.00

Carotene, mg                  1.40                           –

Vitamin PP, mg             1.35                           0.20

Vitamin B9, mg             0.30                           5.00

 Vitamin E, mg               2.00                           0.20                       Minerals

Potassium, mg                179.50                       197.00

Calcium, mg                   40.50                         34.00

Magnesium, mg             17.50                         13.00

Iron, mg                         6.10                           0.30

Phosphorus, mg             100.00                       23.00

Sodium, mg                    21.50                         13.00

Sulphur, mg                   12.00                         9.00

Fructose was used as a sweetener. Fructose is slowly absorbed in the intestine and has a glycaemic index of

20. Thus, this contributes to a smooth increase in blood glucose levels, which is especially important for dia- betic people. Fructose is 1.75 times as sweet as sucrose and thus can be added to products in smaller quantities to reduce the amount of sucrose by 30–50%. Currently, fructose is used in the production of functional and diet foods, including those for children [28].

2. Developing a formula for diet fruit jelly. A num- ber of experimental studies were conducted to develop products with different ratios of the main raw materials (see ‘Study Objects and Methods’).

To make fruit jelly dietetic, sugar was replaced with a smaller amount of fructose: it is sweeter than  su- crose. This made it possible to significantly increase the

amount of puree in the formula. In addition, fructose en-

hanced the flavour of the fruit jelly.

Table 2 shows the fruit jelly formula developed. Studies were conducted to measure how the plas-

tic strength of the viburnum-and-orange-based samples made with different amounts of gelatin changed accor- ding to the duration of curing, compared to the control sample and the gelatin-free sample.

The gelatin-free jelly had a poor plastic strength of

5.3 kPa (Fig. 1, curve 2), because the amount of pectin contained in viburnum puree is not enough for strong jelly to form.

The percentage of gelatin powder in the test sam- ples was 3%, 5%, and 7% of the formula mass (Fig. 1,

curves 3, 4, and 5). Fig. 1 shows how increased amounts of gelatin affected the plastic strength of the jelly mass. With a gelatin amount of 5%, the plastic strength al- most reached the value of the control sample (17 kPa), and with a higher amount, it even exceeded it. Thus, we chose a 5% duantity of gelatin powder.

The glycaemic index (GI) of the samples was calcu- lated by measuring the amount of glucose accumulated during the product breakdown in vitro.

The analysis (Fig. 2) showed that replacing  sugar with fructose reduced the jelly GI almost by half (29.2–

32.8 for test samples 1–5 vs. 58.4 for the control sample). This can be explained by a low GI of fructose compared to sucrose (19 vs.75). Some variation of the GI in the test samples seems to be associated with different propor- tions of viburnum and orange puree in their formulas. The predominance of viburnum puree leads to a slight decrease in the GI.

Table 3 demonstrates the comparison of the nutri- tional value of five jelly samples with that of the control. As can be seen, all the test samples had a higher content of protein, fats, vitamins, macro- and microelements, compared to the control sample, and almost half of its carbohydrate content and energy value.

The analysis of sensory and physicochemical char- acteristics of the samples was carried out with expert qualimetry methods by the Department of Grain Pro- cessing, Baking, Pasta and Confectionery Technologies at K.G. Razumovsky Moscow State University of Tech- nology and Management.

Table 2. Diet fruit jelly formula based on viburnum and orange puree

Raw material                    Dry matter mass fraction, %                          Total raw material per 1 ton of finished product, kg

*Note: the control sample was based on the moulded apple jelly formula. Tests 1–5 refer to the samples with a different proportion of viburnum and orange puree, namely: 75:2; 60:40; 50:50; 40:60; and 25:75.

The validity of the results was evaluated by analy- sing the consistency of expert (consumer) opinions using the coefficient of concordance:

n

å d j

12        2

Curing duration, min

Curve 1 (control),       Curve 2 (gelatin-free),        Curve 3

(3% gelatin),        Curve 4 (5% gelatin),       Curve 5 (7% gelatin)

m2 (n3 - n)

where d j  is the deviation of the rank sum for the j-th pa- rameter from the average rank sum.

If there are equal ranks among those given by one expert (consumer), the coefficient of concordance is cal- culated as follows:

n

                                ,

m2 (n3

m

• n)- måTk

Tk   = å(tk   - tk )

Twenty respondents aged 20 to 50 took part in the tasting to identify the product relevance among consu- mers of different age groups.

Of different survey methods used (such as intervie- wing or questionnaire), interviewing proved most pro- ductive: the respondents took the initiative and ex- pressed well-argued opinions.

1. 1. Qualimetric modelling as a method of evalu-

k =1

where tk is the number of equal ranks in the k-th group.

The  coefficient  of  concordance  W   ranges  from

0 to 1. W = 1 means complete consistency of expert opinions, W > 0,5 means  satisfactory  consistency,  and W < 0,5 means poor consistency.

Table 3. Nutritional value of the control and test samples

ating consumer properties. The key stage of customer

Con-

Test 1   Test 2    Test 3    Test 4    Test 5

satisfaction assessment was data processing based  on

                     trol                                                                            

Table 4. Qualimetric models of test jelly samples

No. sample               Proportion of ingredients                    Qualimetric model

1. Viburnum 75 / Orange 25
2. Viburnum 25 / Orange 75
3. Viburnum 40 / Orange 60
4. Viburnum 60 / Orange 40
5. Viburnum 50 / Orange 50

P = 0.20x1 + 0.18x2  + 0.16x3  + 0.17x4  + 0.15x5  + 0.13x6 P = 0.19x1 + 0.19x2  + 0.17x3  + 0.15x4  + 0.15x5  + 0.15x6 P = 0.11x1  + 0.11x2  + 0.20x3  + 0.17x4  + 0.21x5  + 0.20x6

P = 0.14x1  + 0.16x2  + 0.17x3  + 0.16x4  + 0.18x5  + 0.18x6

P = 0.14x1  + 0.15x2  + 0.17x3  + 0.14x4  + 0.20x5  + 0.19x6

Table 5. Sensory and physicochemical characteristics of test samples

Indicator              Test sample 1                    Test sample 2                Test sample 3                 Test sample 4                Test sample 5

Sensory characteristics

Colour                Saturated, vivid bur- gundy

Saturated orange            Unsaturated, pale ma-

roon

Unsaturated, pale or- ange

Unsaturated, pink

Taste                  Sweet, with a pro- nounced taste of viburnum and a hint of orange

Aroma                Pronounced aroma of viburnum with a hint of orange

Texture               Elastic, gelatinous, tender

Shape                 Consistent with this type of fruit jelly

Sweet, with a domi- nant taste of orange and a hint of vibur- num

Pronounced aroma of orange with a hint of viburnum

Elastic, gelatinous, tender

Consistent with this type of fruit jelly

Sweet taste of orange and viburnum (domi- nated by orange)

Aroma of viburnum with a light hint of or- ange

Elastic, gelatinous, tender

Consistent with this type of fruit jelly

Sweet taste of orange and viburnum (domi- nated by viburnum)

Aroma of viburnum with a fruity hint

Elastic, gelatinous, tender

Consistent with this type of fruit jelly

Sweet, unpro- nounced taste of fruit and berries

Aroma of vibur- num and orange

Elastic, gelatinous, tender

Consistent with this type of fruit jelly

Surface                Smooth and shiny             Smooth and shiny         Smooth and shiny          Smooth and shiny         Smooth and shiny Physicochemical characteristics