The effect of different sugar substitutes on quality characteristics and hydroxymethyl furfural (HMF) levels of cakes

Increased sugar consumption is known to be associated with obesity and many health problems such as type 2 diabetes, metabolic syndrome, cardiovascular diseases. Nowadays, people are becoming more concerned about their health, which has led to the acceleration of studies investigating healthier alternatives that will create the desired sweet taste in foods. Especially plant syrups, juices, extracts, concentrates, which are in the category of traditional sweeteners rich in bioactive components, have started to be used frequently in the food industry and in our homes. The aim of this study was to investigate the usage possibilities of some traditional sweeteners (liquid stevia, agave syrup, date juice, apple juice concentrate) used as sugar substitutes in cakes by physical (colour, texture, structural properties, baking loss and yield), chemical (pH, aw, general chemical composition, HMF) and sensory analyses and to investigate their effect on HMF which is considered as one of the most important chemical contaminants in bakery products. After determining the standard recipe, the usage recommendations in the product information were taken into consideration in determining the amounts of traditional sweeteners to be substituted for sucrose. Means for all chemical, physical and sensory analyses were evaluated by 'One Way ANOVA' test and Tukey/Tamhane multiple comparison tests were applied. The relationship between HMF and browning index and L* was evaluated by Spearman correlation test. p value less than 0,05 was considered statistically significant. As a result of the study, the total colour changes of the inner and crust colour of all substituted cakes compared to the control group (sucrose) were visually noticeable (ΔE>3). Hardness value, baking loss, water activity means of all substituted cakes were significantly higher and volume and symmetry index means were lower (p<0,05) compared to the control group. The 100% substitution of sucrose with conventional sweeteners significantly decreased the energy and carbohydrate contents of the cakes (p<0,05). Among the sugar substitutes, the cake sweetened with liquid stevia (2,87±0,21 mg/kg) (which has the lowest HMF level) had the lowest HMF level (16,70±4,18 mg/kg) and the cake sweetened with date juice (3457,00±49,69 mg/kg) (which has the highest HMF level) had the highest HMF level (405,55±29,70 mg/kg). The HMF content of the cake sweetened only with liquid stevia was lower than the control group (61,48±11,78 mg/kg) and this was statistically significant (p<0,05). A statistically significant (p=0,009, p=0,002 respectively) and moderate (r=0,420, r=(-0,493), respectively) correlation was found between HMF level, browning index and L* value. The control group had the highest score for each parameter in sensory analysis. The closest sensory analysis scores to the control group belong to the cake substituted with stevia. In our study, the sensory analysis scores of the cakes sweetened with agave syrup, date juice and apple juice concentrate were similar for all parameters (p>0,05) and lower than the other groups (p<0,05). When all analyses were evaluated, the cake sweetened with stevia seems to be the best alternative with low HMF content and high sensory analysis scores compared to other substitutes. Further studies are needed to determine the sweetness ratios of sugar substitutes, to investigate the possibilities of their use in bakery products and to develop new formulations to improve quality and sensory properties.