INTRODUCTIONModern confectioners prioritize new formulationswith a reduced sugar content, lower energy value,extended shelf life, and improved quality. Thequality of confectionery products is determined byphysicochemical and microbiological processes that takeplace throughout their shelf life. These processes dependon the product’s chemical composition, ingredientratios, storage conditions, moisture content, pH, wateractivity, and moisture transfer. The main indicators ofjelly quality are moisture content, water activity, andpH. They depend on the formulation, the content andproperties of carbohydrate-containing components, aswell as storage conditions [1, 2].Confectionery products vary in moisture thatbinds nutrients and regulates the product’s texture andstructure. Products with high moisture contain largeramounts of free and chemically unbound water thatintensifies biological processes and causes damage toproducts [3]. Free water is responsible for molds, yeasts,and bacteria, as well as toxins. It is involved in chemicaland biochemical reactions that can affect the product’s263Plotnikova I.V. et al. Foods and Raw Materials. 2022;10(2):262–273texture, aroma, color, taste, nutritional value, stability,and shelf life [4].Regulatory requirements for confectionery productsinclude an indicator of water content (W, %). However,this indicator cannot assess how well water is bound tofood substances and how this may affect the quality ofthe product during storage [5].What is vital for microorganisms is not the absolutecontent of water in the product but its availability, orwater activity (Аw). This indicator is defined as Аw = Р/Р0,i.e., the ratio of water vapor pressure over the surfaceof the product (Р) and vapor pressure over purewater (Р0) [6].The relative equilibrium moisture is based onthe partial pressure of water vapor over the productand depends on the product’s chemical composition,moisture content, storage conditions (temperature andrelative air humidity), type of packaging, etc. [7].The Аw limits for microorganisms in food productsare 0.83–0.98 for bacteria, 0.81–0.88 for yeasts, and for0.70–0.88 molds. However, some types of mold fungiand osmophilic yeasts can grow even at Аw = 0.62. Thatis why fungi and yeast contents are included in thosemicrobiological indicators that determine the product’sstability during storage. All types of microorganismsare capable of reproduction at Аw > 0.95 and none canreproduce at Аw < 0.6.The pH and redox potential values have a significanteffect on the growth of microorganisms. Products withpH < 3.7 are safe from spoilage, with only lactic acidbacteria and certain yeasts and molds able to develop inthem, while products with pH of 5.0 to 7.0 are exposedto risks associated with pathogenic microorganisms [8].Based on water activity (Аw), products can be dividedinto high moisture (Аw ˃ 0.9), intermediate moisture(0.6 ˂ Аw ˂ 0.9), and low moisture (Аw ˂ 0.6) products.Low moisture prevents microbiological processes in theproduct, contributing to a long shelf life. Intermediatemoisture creates favorable conditions for predominantlymicrobiological and enzymatic processes with a growthof yeasts, molds, and some types of bacteria, thuscausing the products to dry out and become stale duringstorage. High moisture products are vulnerable to alltypes of microorganisms and therefore have a short shelflife [9].Reducing the water activity index can effectivelyprevent microbiological spoilage and some chemicalreactions in food products that reduce their qualityduring storage. For this, a number of methods areapplied including concentration, dehydration, drying,freezing, increasing osmotic pressure over the product,and using microorganism growth inhibitors. Thereare also active ingredients that bind water and therebyprevent or significantly slow down its evaporation.These are specific enzymes, emulsifiers, carbohydratecontaininghygroscopic substances, salts, and waterretainingagents. The strength of water bindingdepends on the origin and chemical composition of theingredients used, as well as pH and temperature of themedium [10, 11].The carbohydrate composition of fruit jelly has asignificant impact on its consumer properties duringstorage. Jelly is a sugary confectionery product. Despiteits popularity, it has a number of disadvantages: highsugar content (70–85% of easily digestible sugars),high energy value (300–360 kcal/100 g), sweetness,high glycemic index, and an unbalanced composition.According to its chemical composition and structure,jelly belongs to complex colloidal systems. Itsosmotically retained moisture has a limited energyof binding with the product’s components. Jelly is anintermediate moisture (15–30%) product [12, 13].During storage, even with all requirements met,jelly gradually becomes exposed to moisture exchange(shrinkage) and sucrose crystallization, with itsappearance and structure deteriorating as well [13].However, when stored at elevated temperatures andrelative humidity over 70%, jelly is vulnerable to molddue to the sorption of moisture on its surface. Thisresults in its wetting, with an increase in the Аw indexto 0.9 and a growth in Aspergillus and Penicilliumfungi, yeast, and, to a lesser extent, bacteria [15]. Thelower limit of jelly moisture for mold fungi is 15%, butunder improper storage conditions, spoilage can occureven with a higher dry matter content. With a sugarconcentration up to 60–65% and increased moisture,some races of yeast can cause fermentation, especiallyalcoholic, which gives the product an unpleasantpungent odor [16].Jelly drying can be prevented and water activityreduced by introducing sugar-containing substanceswith a high content of reducing agents and waterretainingcomponents (polysaccharides, glycerol,polyhydric alcohols, some sweeteners, starch, proteins,amino acids, lactic acid, etc.) [17].Fruit jelly is made with natural gel-forming agentssuch as agar-agar, pectin, gelatin, carrageenans, gumarabic, xanthan gums, etc. These are hydrocolloidalpolysaccharides that bind water in jelly, like sugar,making it less available for microorganisms todevelop [18–20].Pectin is the best water-retaining gelling componentfor jelly. It is a natural polysaccharide with water-solublefiber properties. Pectin is widely used in therapeuticand preventative nutrition due to its normalizingeffect on many vital processes without disturbingthe bacteriological balance of the body. In particular,it improves digestion, lowers blood cholesterol,normalizes blood sugar, and removes ions of toxicmetals, pesticides, radionuclides, xenobiotics, anabolics,metabolic products, and excess urea from the body. Itis recommended to people with disturbed carbohydrateand lipid metabolism, immune and bacterial diseases,obesity, and atherosclerosis [21].Carbohydrates not only determine sensory,functional, and technological properties of a product,264Plotnikova I.V. et al. Foods and Raw Materials. 2022;10(2):262–273but they also regulate its acidity and have a preservativeantimicrobial effect. Adding sugars increases thebinding energy of water in the material and decreasesthe rate of chemical reactions, reducing water activityand microbial growth [22]. However, not only thequantity of sugars is important but also their qualitativecomposition. For example, apple jam with 32.6%moisture has a lower Аw index (0.825) than butter creamwith 15.2% moisture (0.851) due to a significant contentof sugar and reducing sugars [23].Monosaccharides have the greatest ability tobind water and reduce water activity, followed bydisaccharides and polysaccharides. Sugar-containingsubstances can be arranged in the following order basedon their ability to reduce the Аw index in products [24]:Amylopectin MaltohexaoseMaltotriose Sucrose MaltoseLactulose Glucose FructoseXylose Glycerin.Replacing white sugar with alternative starchproducts is one of the ways to reduce sweetnessand easily digestible sugars, slow down drying andstaling, and keep jelly fresh during storage. Thesealternative materials, e.g., starch syrup and glucosefructosesyrup, vary in carbohydrate composition andare technologically advantageous, inexpensive, anddomestically produced in large quantities.We aimed to study the quality of starch syrup(low-conversion, confectionery, and high-conversion)and glucose-fructose syrup, as well as their effect onthe sensory, physicochemical, and microbiologicalparameters of jelly with different carbohydrate profilesafter manufacture and during storage.STUDY OBJECTS AND METHODSSamples of starch syrup and glucose-fructose syrup(Kargill Company, Russia) were analyzed according toState Standard 33917-2016 and Specifications 10.62.13-001-00343579-2016 for the following parameters byusing the following methods:– the dry matter content: by the refractometric method;– the content of reducing substances: by the Lane-Eynonmethod;– the content of carbohydrates: by high performanceliquid chromatography on a Shimadzu LC-2010chromatograph with a RID-10A refractometric detector;– pH value: by measuring the activity of hydrogen ionson a Testo 206 pH meter;– acidity: by titration; and– nutritional value: by calculation.The jelly samples were based on apple pectin. Thecontrol sample was based on sugar and confectionerysyrup in a ratio of 1:0.5. The experimental samples werefree of white sugar and based on starch syrup (lowconversion,confectionery, and high-conversion) andglucose-fructose syrup.The sensory quality of the jelly samples wasevaluated on a 5-point scale by the descriptor-profileanalysis according to State Standard ISO 13299-2015 [25]. It involved the following parameters andmethods of their determination:– the water content: by the refractometric method (StateStandard 5900);– the content of reducing substances: by the ferricyanidemethod (State Standard 5903);– titratable acidity: by titration; and– active acidity (pH): by the potentiometric method(State Standard 5898).Water activity was measured by using a HygroPalmhygrometer (Rotronic, Switzerland) on a scale from0 to 1, with an absolute error of ± 0.008 (± 0.1°C fortemperature). The microbiological indicators wereevaluated against State Standard 6442-2014 andTechnical Regulations of the Customs Union 021/2011.In particular, we applied microbiological researchmethods to determine the total aerobic mesophilic count(State Standard 10444.15-94), coliform bacteria (StateStandard 50474-93), and spoilage microorganisms (StateStandard 10444.12- 88).The jelly samples were stored in food-gradepolyethylene terephthalate containers for 12 weeks at21.0 ± 1.5°C and relative humidity of 82 ± 2%.To prepare the control sample, apple pectin wasmixed with white sugar in a ratio of 1:3. The resultingdry mixture was gradually added to hot water (70–75°С)and vigorously stirred until a homogeneous water-pectinmixture was obtained with a dry matter content of25 ± 1%. Then, we added the remaining amount of whitesugar, starch syrup heated to 50–55°C, and buffer salt(sodium lactate), stirred the mixture, and boiled it toobtain a jelly mass with a 27–29% water content. Themass was then cooled to 85–90°C, with citric acid andа food flavoring agent introduced into it. The jelly masswas poured into rigid molds to mature, dry, and cool.The experimental samples were prepared accordingto the same method as the control, with erythritolused instead of white sugar (Fig. 1). Their ingredients,carbohydrate composition, and energy value arepresented in Table 1.RESULTS AND DISCUSSIONFirst, we studied the quality indicators of threetypes of starch syrup (low-conversion, confectionery,and high-conversion) and glucose-fructose syrupin comparison with those of sugar syrup used toprepare the control sample. The starch syrups differedsignificantly in their carbohydrate composition. Theycontained easily digestible reducing sugars (glucoseand maltose) and polysaccharides (dextries andtrisaccharides), with the latter responsible for dieteticproperties (Table 2). In addition, the syrups containedminerals (0.10–0.37%) such as potassium, phosphorus,sodium, calcium, magnesium, and iron [26]. Unlikesugar syrup, starch syrup is free of sucrose and fructose,265Plotnikova I.V. et al. Foods and Raw Materials. 2022;10(2):262–273Figure 1 Process chart for jelly samples based on sugar-free starch syrup or glucose-fructose syrupTable 1 Ingredients, carbohydrate composition, and energy value of jelly samples with different carbohydrate profilesName of material Control(sugar and confectionerysyrup)Experimental sugar-free samples based on:Low-conversionsyrupConfectionerysyrupHigh-conversionsyrupGlucose-fructosesyrupIngredients: “+” – present, “–” – absentWhite sugar + – – – –Low-conversion syrup – + – – –Confectionery syrup + – + – –High-conversion syrup – – – + –Glucose-fructose syrup – – – – +Erythritol – + + + +Apple pectin + + + + +Sodium lactate (40%) + + + + +Citric acid (50%) + + + + +Food flavoring agent + + + + +Carbohydrates, g/100 g:total 79.1 74.6 74.4 72.2 79.0reducing sugars 14.9(glucose, maltose,fructose)27.8(glucose,maltose)33.2(glucose,maltose)45.8(glucose,maltose)77.3(glucose,maltose)polysaccharides 13.7 46.9 41.4 26.2 –Energy value, kcal 301 311 309 302 311ErythritolCitric acidFood flavoring agentPouring intorigid moldsTempering of jellymass (t = 85–90оС)Sampling, maturation,and dryingCoolingCoatingSortingand packaging by massApplepectinWater(Т=70–75оС)Preparinga pectin solutionBoiling of jelly mass(Тboil=106–108оС, DM=71–73%)Preparinga formulation mixtureApplepectinStarch syrupor glucose-fructose syrupSodium lactate266Plotnikova I.V. et al. Foods and Raw Materials. 2022;10(2):262–273syrup contained more reducing sugars and fewerpolysaccharides (45.8 and 26.2%, respectively) than theother experimental samples. The glucose-fructose syrupsample contained more reducing sugars (77.3%) than theother samples but no sucrose or polysaccharides.Thus, all the samples based on starch syrupcontained 1.9–3.4 times more polysaccharides and1.4–2.4 times fewer reducing sugars than the control.However, the sample based on glucose-fructose syruphad a 1.2 times higher content of reducing sugars.The sensory evaluation of the jelly samples wasbased on the quantitative descriptor-profile analysis. Inthis analysis, each of the main sensory indicators (taste,color, smell, texture) is presented as a set of componentsa highly hygroscopic reducing carbohydrate thatsignificantly increases jelly’s wettability during storage.All the types of starch syrup had a lower sweetnesscoefficient (by 0.2–0.5 units), lower values of activeacidity (by 1.3–1.7 pH units), and a higher ash content(2.0–7.4 times) than the sugar syrup. The highconversionsyrup contained the largest amount ofreducing sugars (62.6%, including 31.8% glucoseand 30.8% maltose) and the smallest amount ofpolysaccharides (19.9%). The low-conversion syrup, onthe contrary, had the highest content of polysaccharides(46.8%) and the lowest content of reducing sugars(32.3%, including 14.5% glucose and 17.8% maltose).The confectionery syrup contained 40.4% of reducingsugars (20.8% glucose, 19.6% maltose) and 38.3% ofpolysaccharides. The glucose-fructose syrup had a lowervalue of active acidity (by 3.6 pH units) and a highersweetness coefficient (by 1.2) than the sugar syrup. Thiswas due to its significant content of easily digestiblereducing sugars (70.5%, including 28.6% fructose,38.8% glucose, 3.1% maltose) and the absence of sucroseand polysaccharides.Replacing sugar with starch syrup or glucosefructosesyrup significantly changed the carbohydratecomposition of the jelly samples (Table 1). This notonly depended on the chemical composition of theraw materials but also the chemical processes in thejelly mass during boiling. Unlike the control, theexperimental samples contained no sucrose.The control sample had 65.4% of easily digestiblecarbohydrates, including 50.5% of sucrose and 14.9% ofreducing sugars (fructose, glucose, and maltose), as wellas 13.7% of polysaccharides. The samples based on lowconversionsyrup had a lower content of reducing sugars(glucose and maltose) and more polysaccharides (27.8and 46.9%, respectively) than the other experimentalsamples. The samples based on confectionery syrupcontained 33.2% of reducing sugars and 41.4% ofpolysaccharides. The samples based on high-conversionFigure 2 Sensory evaluation of jelly samples with variouscarbohydrate profiles012345SweetnessTaste richnessCooling effectPresence of yellowtintColor saturationTransparencyMaterial-specific smellSmell intensityOff-odorJelly-like textureViscoelasticity andplasticityStickinessControlLow-conversion syrupConfectionery syrupHigh-conversion syrupGlucose-fructose syrup012345SweetnessTaste richnessCooling effectPresenceof yellow tintTransparencyColor saturationMaterial-specific smellSmell intensityOff-odorViscoelasticityand plasticityJelly-liketextureStickinessTable 2 Quality indicators and carbohydrate composition of starch syrup, glucose-fructose syrup, and sugar syrupQuality indicatorsand carbohydratesSugar syrup(1:0.5)Starch syrup Glucose-fructose syrupLow-conversion Confectionery High-conversionDry matter content, % 80.2 79.3 78.9 83.0 70.6Content of reducing substances(or dextrose equivalent), %14.5 32.3(26–35*)40.4(36–44*)62.6(45 and over*)70.5Content of carbohydrates, %: 80.1 79.1 78.7Ц 82.5 70.5– sucrose 50.6 – – – –– glucose 6.3 14.5 20.8 31.8 38.8– fructose 2.5 – – – 28.6– maltose 5.7 17.8 19.6 30.8 3.1– polysaccharides (dextrins) 15.0 46.8 38.3 19.9 –Active acidity, pH units 6.4 5.1 5.0 4.7 3.6Sweetness coefficient, units 0.8 0.3 0.4 0.6 1.2* according to State Standard 33917-2016267Plotnikova I.V. et al. Foods and Raw Materials. 2022;10(2):262–273(or descriptors) that are scored by the panelistsaccording to their presence and intensity. The results aregraphically depicted in the form of a profile diagram.In our study, 20 panelists aged 19–23 evaluatedthe following sensory indicators of the jelly samples(descriptors listed in brackets): taste (sweetness,richness, cooling effect); color (yellow tint, saturation,transparency); smell (material-specific smell, intensity,off-odor); and texture (jelly-like, viscoelasticity andplasticity, stickiness).Figure 2 shows the profile diagram of the jellyquality evaluated on a 5-point scale of intensity withweight coefficients representing the significance of eachindicator.The descriptor-profile analysis showed that thesamples based on high-conversion syrup and glucosefructosesyrup had the greatest sweetness, taste richness,color saturation, and transparency. Also, the sample withglucose-fructose syrup had a slight effect of stickinesson its surface. This was because it had the highestcontent of reducing sugars (mostly fructose) which turninto coloring, humic substances and aldehydes duringboiling and intensify the product’s color, aroma, andhygroscopicity.The jelly based on low-conversion syrup had thelowest sweetness, taste richness, and color brightness,as well as low texture density and elasticity. Thesevalues can be explained by its highest content ofpolysaccharides which bind less water and thereforemake the product less viscous and strong. The samplebased on confectionery syrup had the most optimalprofile, with moderate sweetness and taste richness,good jelly-like texture, viscoelasticity, and plasticity, noeffect of wetting or stickiness, and a color similar to thatof the control.The jelly samples with various carbohydratecompositions were packed in plastic containersand stored for 12 weeks to study changes intheir water content (W), water activity (Aw), andpH (Table 3). The initial (after preparation) watercontents in the control sample, the starch syrupbasedsamples, and the jelly based on glucosefructosesyrup were 20.8 ± 0.2, 19.1 ± 0.2–20.0 ± 0.1,and 20.6 ± 0.1, respectively. Тheir pH values were3.4, 3.0–3.3, and 2.8, respectively.All the jelly samples showed a gradual decrease inthe water content and changes in water activity duringstorage. After 12 weeks of storage, the control samplehad the highest loss of water (38.9%), compared to theexperimental samples (17.0–28.3%). This was becauseit contained a significant amount of sucrose (50.6%)and a small amount of reducing substances (14.9%). Inthe process of moisture transfer during storage, sucrosecrystallization centers gradually began to develop onthe sample’s surface. They subsequently grew in sizeforming a thin crystalline sugar crust and graduallysugaring the whole product. During this process, freemoisture quickly left the intercrystalline space, causingthe product to dry out and stale.The jelly based on low-conversion syrup was losingwater more slowly than the control but faster than theother experimental samples at the beginning of storage.This was due to its significant content of polysaccharides(46.9%), which bind and retain water to a lesser extentthan reducing substances. Since mold appeared on itssurface after 5 weeks of storage, the studied parameterswere no longer determined. The jellies based onconfectionery syrup and high-conversion syrup hadlower water losses (28.3 and 24.5%, respectively),compared to the control. The lowest water loss (17.0%)was registered in the sample based on glucose-fructoseTable 3 Water content changes in the jelly samples with various carbohydrate profiles during storageStorage time, weeks Water content in the jelly samples based onSugar andconfectionery syrup(control)Low-conversionstarch syrupConfectionerystarch syrupHigh-conversionstarch syrupGlucose-fructosesyrup0 (after drying) 20.8 ± 0.2 19.5 ± 0.1 19.1 ± 0.2 20.0 ± 0.1 20.6 ± 0.11 19.4 ± 0.1 18.1 ± 0.1 18.7 ± 0.3 19.6 ± 0.1 20.1 ± 0.12 18.8 ± 0.1 17.8 ± 0.2 18.4 ± 0.3 19.1 ± 0.1 19.8 ± 0.23 17.3 ± 0.1 17.6 ± 0.3 17.9 ± 0.2 18.9 ± 0.2 19.5 ± 0.14 16.8 ± 0.2 17.3 ± 0.2 17.5 ± 0.2 18.6 ± 0.1 19.1 ± 0.25 16.3 ± 0.3 17.1 ± 0.1 17.2 ± 0.2 18.2 ± 0.2 18.9 ± 0.16 15.9 ± 0.2 mold appeared onthe surface.water content notdetermined16.8 ± 0.1 17.8 ± 0.1 18.7 ± 0.17 15.4 ± 0.2 16.2 ± 0.2 17.4 ± 0.2 18.5 ± 0.38 15.0 ± 0.1 15.6 ± 0.2 16.8 ± 0.2 18.2 ± 0.29 14.6 ± 0.2 15.0 ± 0.2 16.4 ± 0.3 17.9 ± 0.110 14.1 ± 0.1 14.7 ± 0.1 15.9 ± 0.2 17.7 ± 0.211 13.5 ± 0.3 14.1 ± 0.2 15.6 ± 0.2 17.4 ± 0.212 12.7 ± 0.1 13.7 ± 0.2 15.1 ± 0.1 17.1 ± 0.1Changes in water content after 3 months of storage, % of the initial value:ΔW, % –38.9 – –28.3 –24.5 –17.0268Plotnikova I.V. et al. Foods and Raw Materials. 2022;10(2):262–273Figure 3 shows the changes in water activity in thepackaged jelly samples during 12 weeks of storage. Aswe can see, the longer was the storage time, the lowerwas water activity in all the samples. We also found thatthe lower was the water loss, the more changes in wateractivity it caused (Fig. 4).The decrease in water activity was associated withtwo processes – water loss during storage and the use ofstarch products with a different ratio of mono-, di-, andpolysaccharides. Monosaccharides reduce water activityto a greater extent than disaccharides due to theirsolubility and hygroscopicity. The solubility of monosyrup.It contained the largest amount of reducingsubstances (fructose and glucose), which contributed toslower drying and greater freshness preservation.Thus, the jelly’s carbohydrate composition (the ratioof mono-, di-, and polysaccharides) significantly affectedthe process of moisture exchange during storage andtherefore the product’s drying and staling. Using varioustypes of starch syrup and glucose-fructose syrup with ahigh content of reducing sugars (especially glucose andfructose with higher solubility than maltose or dextrins)significantly slowed down the drying of jelly andincreased its shelf life.Figure 3 Water activity in jellies with various carbohydrate compositions during storage: 1 – control (based on sugar andconfectionery syrup); sugar-free samples: 2 – based on low-conversion syrup; 3 – based on confectionery syrup; 4 – basedon high-conversion syrup; 5 – based on glucose-fructose syrup0.40.50.60.70.80.90 1 2 3 4 5 6 7 8 9 10 11 12Water activity, АwStorage time, weeks23541Mold appeared, the parameterno longer determinedFigure 4 Water activity in jellies with various carbohydrate compositions after preparation and after 12 months of storage:1 – control (based on sugar and confectionery syrup); sugar-free samples: 2 – based on low-conversion syrup; 3 – based onconfectionery syrup; 4 – based on high-conversion syrup; 5 – based on glucose-fructose syrup0.7240.8390.7890.7490.6640.4010.5730.421 0.4020.40.50.60.70.80.91 2 3 4 5after preparation after 12 months of storageWater activity, Аw43.8 %Moldappeared,the parameterno longerdetermined44.6 %27.4 %39.5 %Jelly samples0.7240.8390.7890.7490.6640.4010.5730.421 0.4020.40.50.60.70.80.91 2 3 4 5after preparation after 12 months of storageWater activity, Аw43.8 %Moldappeared,the parameterno longerdetermined44.6 %27.4 %39.5 %Jelly samples269Plotnikova I.V. et al. Foods and Raw Materials. 2022;10(2):262–273Table 4 Sensory indicators of jelly samples with various carbohydrate profiles during storage*Indicator Jelly samples based onSugar andconfectionery syrup(control)Low-conversionstarch syrupConfectionerystarch syrupHigh-conversionstarch syrupGlucose-fructosesyrupTaste, color, smell Sickeningly sweet,bright yellow,no off-odorSlightly sweet,yellow-beige,a subtle smell ofsyrupModerately sweet,yellow with agolden tint, a subtlesmell of syrupSweet, yellow, nooff-odorSweet,bright yellow withan orange tint,no off-odorTexture Homogeneous, jelly-like, viscoelastic, plastic,Quite dense Slightly dense Quite dense Quite dense Quite denseShape Regular, with anindistinct contourdue to sucrosecrystallization onthe surfaceRegular,with a clear contour,no deformationRegular,with a clearcontour,no deformationRegular,with a clearcontour,no deformationRegular, with anindistinct contourdue to sagging ofwet areas of thesurfaceSurface Not sticky,covered with a finecrystalline sugarcrust, transparentNot sticky,without a crystallinecrust,transparentNot sticky,without a crystallinecrust,transparentNot sticky, a finecrystalline crustbeginning to formdue to glucosecrystallization,transparentSlightly wet andsticky,transparent*The control and the experimental samples based on confectionery syrup, high-conversion syrup, and glucose-fructose syrup were evaluated after12 weeks of storage; the sample based on low-conversion syrup was evaluated after 5 weeks of storageand disaccharides varies greatly, amounting (at 100 °C)to 98.4, 87.7, 86.1, and 82.9% for fructose, glucose,maltose, and sucrose, respectively [27, 28]. Fructosecontributes to the greatest decrease in water activity,followed by glucose, maltose, and sucrose. The tendencyof sugar molecules to hydration is associated with thepresence of hydroxyl and aldehyde groups capable offorming hydrogen bonds with water molecules. Themore reducing sugars the product contains, the morethey bind water molecules and slow down its staling [29].According to the sorption isotherm (Fig. 5), theinitial water activity values in all the jelly samplesranged from 0.664 ± 0.012 to 0.839 ± 0.011. Therefore,we can classify them as intermediate moisture products.Figure 5 shows a certain correlation between thewater content and the water activity index that isdetermined by both the content of carbohydrates andtheir ratio in the sample. The control sample had thegreatest decrease in water activity, namely 44.6%(Fig. 4). The sample based on low-conversion syruphad the highest initial value of water activity (0.839).This was due to its low content of reducing sugars witha preservative effect and high water-binding capacity,which led to gradual molding after 5 weeks of storage.The water activity values of the samples based on highconversionsyrup and glucose-fructose syrup wereinitially lower than in the other samples (0.749 and0.664, respectively). After 12 weeks of storage, theydecreased more than in the other samples (by 43.8and 39.5%, respectively) due to significant amounts ofreducing sugars in their composition (45.8 and 77.3%,respectively). The sample based on confectionery syruphad the lowest decrease in water activity, namely 27.4%(Fig. 4). During storage, this sample dried more slowlythan the control. It did not get wet and retained itsviscoelasticity and plasticity, with no crystalline crustforming on its surface.The sensory indicators of the jelly samples after12 weeks of storage are presented in Table 4.The antimicrobial effect of carbohydrates isprimarily based on decreasing water activity, whichslows down most chemical reactions responsible for theproduct’s deterioration, increases the binding energyof water, and reduces the ability of microorganisms touse it for metabolism. High water content (21–15%) andwater activity (0.6–0.8) in jelly are among the causes ofits microbiological spoilage, leading to the developmentof molds and yeasts [30, 31].In our samples, the water content was 19.1–20.8%and water activity varied from 0.664 ± 0.012 to 0.839 ±0.011, which might indicate possible development ofmicroorganisms and mold. Therefore, we decidedto study changes in the microbiological indicatorsthroughout the entire shelf life of the jelly samples.Based on the Technical Regulations of the CustomsUnion 021/2011, we determined the total numberof pathogenic microorganisms, aerobic mesophilicbacteria, molds and yeasts, spore-forming bacteria, andcoliform bacteria in the jelly samples. We analyzedtheir microbiological stability after storage and foundthat the indicators under study did not exceed thetolerance levels in the control and the experimentalsamples based on confectionery syrup, high-conversionsyrup, and glucose-fructose syrup. Also, we detected nopathogenic microorganisms or coliform bacteria in thesamples (Table 5).270Plotnikova I.V. et al. Foods and Raw Materials. 2022;10(2):262–273high acidity could be used to increase the carbohydratecontent and acidity in the product.Thus, changing the concentration of carbohydrateswith different water-retaining properties can havean additional preservative effect on jelly in combinationwith other technological factors. The risk ofmicrobiological spoilage can be reduced not only byadjusting the formulation (lowering water activityand pH), but also by ensuring low levels of initialmicrobiological contamination of the product.CONCLUSIONOur study showed that jelly can be producedwith various types of starch syrup (low-conversion,confectionery, and high-conversion) or glucose-fructosesyrup used instead of white sugar. This can expand therange of jellies with different carbohydrate profiles andprolong their shelf life.We found that using starch or glucose-fructosesyrups significantly changed the carbohydratecomposition of the jelly. Unlike the control, theexperimental samples did not contain any sucrose. Thestarch syrup-based samples had more polysaccharides(1.9–3.4 times) and fewer easily digestible reducingsugars (1.4–2.4 times), while the sample with glucosefructosesyrup had a higher content of reducing sugars(1.2 times) than the control. The sample based onconfectionery syrup had the most optimal profile, withmoderate sweetness and taste richness, good jellyliketexture, viscoelasticity and plasticity, no effect ofwetting or stickiness, and the color similar to that of thecontrol sample.Different amounts and ratios of mono-, di-, andpolysaccharides significantly affected the moisturetransfer and the preservation of jelly freshness after12 weeks of storage. The control sample had thegreatest water loss (38.9 %), compared to the experimentalsamples. The samples based on high-conversionsyrup and glucose-fructose syrup were least subjectedto drying due to high contents of reducing sugars,especially fructose and glucose, highly hygroscopicsugars that can bind water and slow down the processThe jelly based on low-conversion syrup had itscounts of aerobic mesophilic bacteria, molds, and yeastsexceeding the tolerance levels 2.3, 1.9, and 1.8 times,respectively. This can be explained by a low content ofreducing sugars with a preservative effect and a highwater activity index in this sample. To improve itsmicrobiological indicators and reduce water activity, alarger amount of a preservative agent should be addedto its formulation. For example, it could be a sweetenerwith low sugar and calorie contents and a high waterbindingcapacity (erythritol, sorbitol, xylitol, etc.).Alternatively, some food acid or concentrated juice withTable 5 Microbiological indicators of jelly samples with various carbohydrate profiles during storage*Indicator TechnicalRegulationsof the CustomsUnion 021/2011(tolerance)Jelly samples based onSugar andconfectionerysyrup(control)LowconversionstarchsyrupConfectionerystarchsyrupHighconversionstarchsyrupGlucosefructosesyrupPathogenic microorganisms, incl.salmonella (not allowed), g25 Not detectedAerobic mesophilic bacteria, CFU/g max 1×103 1.5×102 2.3×103 0.8×103 2.8×102 1.4×102Coliform bacteria (not allowed), g (cm3) 0.1 Not detectedMolds, CFU/g max 100 24 105 64 43 16Yeast, CFU/g max 50 18 54 36 24 14*The control sample and the experimental samples based on confectionery syrup, high-conversion syrup, and glucose-fructose syrup wereevaluated after 12 weeks of storage; the sample based on low-conversion syrup was evaluated after 5 weeks of storageFigure 5 The sorption isotherm of the jelly samples withvarious carbohydrate compositions: 1 – control (based onsugar and confectionery syrup); sugar-free samples:2 – based on low-conversion syrup; 3 – based on confectionerysyrup; 4 – based on high-conversion syrup;5 – based on glucose-fructose syrupR² = 0.99630.350.450.550.650.750.8512 14 16 18 20 22Water activity, AwWater content, %1 2 3 4 5АААААBCCCCStorage time:А – 0 weeks (after drying);B – 5 weeks (appearance of mold);C – 12 weeks.R² = 0.99630.350.450.550.650.750.8512 14 16 18 20 22Water activity, AwWater content, %1 2 3 4 5АААААBCCCCStorage time:А – 0 weeks (after drying);B – 5 weeks (appearance of mold);C – 12 weeks.R² = 0.99630.350.450.550.650.750.8512 14 16 18 20 22Water activity, AwWater content, %1 2 3 4 5АААААBCCCCStorage time:А – 0 weeks (after drying);B – 5 weeks (appearance of mold);C – 12 weeks.271Plotnikova I.V. et al. Foods and Raw Materials. 2022;10(2):262–273of staling. The water activity index of the jelly samplesafter preparation ranged from 0.664 ± 0.012 to 0.839 ±± 0.011, so they were classified as intermediate moistureproducts. After storage, this index decreased most in thesamples based on high-conversion and glucose-fructosesyrups and least in the sample based on confectionerysyrup.The microbiological indicators of all the samples,except for the jelly based on low-conversion syrup,did not exceed the standard tolerance levels. Neitherdid we detect any pathogenic microorganisms orcoliform bacteria in them. The jelly based on lowconversionsyrup had its counts of aerobic mesophilicbacteria, molds, and yeasts exceeding the tolerancelevels 2.3, 1.9, and 1.8 times, respectively. To improveits microbiological indicators and reduce wateractivity, a larger amount of a preservative shouldbe added to its formulation, such as a sweetener(erythritol, sorbitol, xylitol, etc.), a food acid, ora concentrated juice with high acidity that canincrease the carbohydrate content and acidity in theproduct.CONTRIBUTIONI.V. Plotnikova reviewed the literature on thestudy problem, proposed a methodology for theexperiment, conducted the experiment, processedexperimental data, performed calculations, and editedthe manuscript. G.O. Magomedov developed the studyconcept and supervised the experiment. I.M. Zharkovareviewed the literature on the study problem andedited the manuscript. E.N. Miroshnichenko edited themanuscript for submission. V.E. Plotnikov conductedthe experiment, processed experimental data, andperformed calculations.CONFLICT OF INTERESTAll the authors were equally involved in writing themanuscript and are responsible for plagiarism.ACKNOWLEDGEMENTSWe thank Raisa I. Ivanova, General Director of theConfectionery Factory (Vologda), for providing rawmaterials and an opportunity to test the samples inindustrial conditions.