Classification and statistical analysis of the nutritional value of commercially available breads in Romania

Abstract

Bread is one of the most fundamental and widely consumed staple foods, therefore, a detailed analysis and comparison of the nutritional value of commercially available bread products can provides valuable insights for both consumers and producers.

In this study, the nutritional compositions of 60 bread products from wholesalers operating on the Romanian market was evaluated. A comparative analysis was carried based on the energy, macronutrient, and salt content within the product category. On average, bread contained 1026 kJ/100 g energy, derived from 2.52 g of fat, 44.46 g of carbohydrates, and 9 g of protein. The average fiber and salt contents of the analyzed bread samples were 9 g and 1.25 g/100 g, respectively. For classification of the bread samples and the statistical evaluation of the data, hierarchical cluster analyses and descriptive statistics methods were applied.

The nutritional composition of commercially available breads in Romania showed significant variation in energy, fiber, fat, and salt content depending on bread type and formulation. Potato bread had the lowest energy and fat content, while white and specialty breads exhibited higher energy or fat levels, and whole-grain breads provided the highest dietary fiber content.

Supplementary Information

The online version contains supplementary material available at https://doi.org/10.1186/s40795-026-01303-6.

Introduction

Bread is among the most widely consumed staple foods worldwide. To meet evolving consumer demands, bread manufacturers continuously diversify their product portfolios [1]. Innovations in bread production are ongoing, with increasing emphasis on the incorporation of whole grains, seeds, and alternative flours to enhance the nutritional quality and promote healthier options [2, 3]. Bread consumption in Romania is considerably higher than that reported for many other European countries and regions, according to available comparative studies [4]. According to data reported by American Institute of Baking International, the average bread consumption in Romania in 2016 was 97 kg per capita per year [5]. During the period 2015–2019, the average 82 annual consumptions was estimated at 82 kg per capita [6].

Bread is an important contributor to daily energy intake, mainly because of its high carbohydrate content; it also supplies small amounts of protein. In addition, bread represents a significant source of minerals and vitamins, including iron, calcium, phosphorus, zinc, potassium and magnesium, as well as vitamin B groups can be mentioned [7–10]. A single slice of bread provides approximately 2 g of protein, 18 mg of calcium and 0.4 mg of iron. In this context, wheat flour classification according to Romanian and European Union legislation—based on protein (gluten) and ash content—plays an important role in determining bread type and its nutritional characteristics [11, 12]. Various additives, such as fats, milk, milk solids, eggs, and antioxidants, may be incorporated into bread formulations to enhance nutritional value, improve texture and flavor, and extend shelf life [13, 14].

During bread production, flours with a high protein content and strong gluten quality are required, as these properties enable the dough to withstand the technological stresses of mixing and leavening [15–17]. Yeast is the most commonly used leavening agent, while artisanal breads are traditionally produced using sourdough-based fermentation (known in Romania as “Maia”) [18]. These methods contribute to the distinctive taste and quality of Romanian bread, setting it apart from products manufactured in other countries. Despite modern advancements in the baking industry, the cultural significance of traditional practices remains pronounced, reflecting the longstanding importance of bread in Romanian society [19]. As consumer preferences shift towards healthier and more diverse products, the bread industry continues to innovate while preserving the essential characteristics of traditional bread-making techniques.

The primary objective of this study was to evaluate and compare the nutritional composition of different types of breads commercially available in Romania, with the aim of providing a comprehensive overview of their nutrient profiles for both consumers and stakeholders.

Materials and methods

The primary objectives of this study were to determine the energy content (kJ/100 g), macronutrient composition (fat, carbohydrates, protein), fiber, and salt content of commercially available bread products on the Romanian market, while the secondary objectives included the classification of bread samples using hierarchical cluster analysis and the identification of potential nutritional patterns. A total of 62 bread products were collected from a local market in Miercurea Ciuc, Romania, and their nutritional parameters per 100 g—energy, total fat, saturated fatty acids, carbohydrates, sugars, fiber, protein, and salt—were recorded based on package labeling. Bread samples were classified into distinct types based on package labeling information, including ingredient composition and declared bread category, rather than weight or manufacturer. For analytical purposes, the samples were grouped into five categories: white bread (N = 11), toast bread (N = 11), whole meal bread (N = 11), specialty bread (N = 15), and potato bread (N = 14). Each category was analyzed separately to evaluate nutritional differences, with detailed data provided in the supplementary material (Table S1). The collected data were subjected to statistical analysis. Descriptive statistics (minimum, 25th percentile, median, mean, 75th percentile, and maximum), were calculated to identify patterns and to characterize the nutritional properties of the different bread types. Statistical evaluation of the parameters was performed using one-way ANOVA. Data distribution was visualized using boxplots, which provided a clear representation of the variability and central tendencies within the dataset. Outliers in the dataset were assessed using Dixon’s Q test, which is suitable for detecting single extreme values in small sample sizes. In addition, surface radar charts were generated in Microsoft Excel 2016 to enable comparative analysis of characteristics across the bread categories.

For the analysis of data distribution, histograms were generated using the Data Analysis add-in of Microsoft Excel. To examine relationships between variables, a Pearson correlation coefficient matrix was calculated with the statistical software R (version 4.2.2). Hierarchical cluster analysis was performed to classify the nutritional profiles of the bread samples, employing IBM SPSS Statistics (version 22). Centralized clustering with Euclidean distance was applied to group the clusters. Furthermore, Principal Component Analysis (PCA) was conducted in IBM SPSS (version 22) to reduce data dimensionality and to identify the principal factors underlying the variability in the nutritional characteristics across the bread samples.

Results

Descriptive statistics

Analysis of energy content, that potato bread exhibited the lowest energy value at 941 kJ/100 g, whereas white bread displayed the highest at 1070.4 kJ/100 g, corresponding to 14% difference in energy intake when consumed in equivalent amounts. Toast bread presented the second lowest energy content at 1027 kJ/100 g. The whole meal and specialty bread categories occupied intermediate positions within the range, reflecting moderate energy values relative to the other bread types of analyzed. The higher energy content of breads produced from refined flours can be explained by the removal of bran and germ during milling, which increases the relative proportion of easily digestible starch and reduces fiber content, thereby resulting in a higher caloric density compared to whole-grain flours, as reported in previous studies [20, 21]. Although dietary fiber is classified as a carbohydrate, breads enriched with fiber-rich ingredients often show a lower proportion of digestible carbohydrates due to the partial replacement of refined starch with non-digestible carbohydrate fractions [22].

The average fat content of the bread samples varied substantially, ranging from 1.75 to 4.37 g/100 g, with specialty breads exhibiting the highest values and white bread the lowest. Carbohydrate content also differed among bread types, with the highest levels observed in white bread (49.63 g/100 g), followed by whole meal bread (46.51 g/100 g), toast bread (44.7 g/100 g), potato bread (44.39 g/100 g), and specialty bread (39.05 g/100 g). Dietary fiber content ranged from 2.21 to 7.07 g/100 g across the examined bread categories, with potato bread showing the lowest values and whole meal (integral) bread the highest. Similarly, protein content was lowest in toast and potato breads, whereas whole meal (integral) bread exhibited the highest protein levels. Salt content was relatively uniform across all bread types, ranging from 1.14 g/100 g to 1.36 g/100 g, reflecting standardization during the baking process (Table 1) [23].

Table 1.

Descriptive statistics for the studied bread categories

	White	Toast	Integral	Special	Potato	Total
Energetic value, kJ/100 g	1070.4 ± 91**	1027 ± 65	1063 ± 201	1048.24 ± 131	941 ± 100*	1026 ± 131
Energetic value, kcal/100 g	256.36 ± 22**	243 ± 15	251 ± 49	249.79 ± 32	222.68 ± 23*	244 ± 32
Fat, g/100 g	1.75 ± 0.65	2.8 ± 1.32	1.89 ± 1.30	4.37 ± 3.23**	1.35 ± 1.90*	2.52 ± 2.27
Fat from which saturated fatty acids, g/100 g	0.55 ± 0.27	0.61 ± 0.26	0.37 ± 0.22	0.64 ± 0.43**	0.21 ± 0.30*	0.47 ± 0.35
Carbohydrates, g/100 g	49.63 ± 4**	44.7 ± 4.42	46.51 ± 10.74	39.05 ± 9.28*	44.39 ± 4.61	44.46 ± 7.87
Carbohydrates of which sugars, g/100 g	1.79 ± 0.94	3.12 ± 2.05**	2.35 ± 1.56	2.42 ± 1.99	1.75 ± 1.64*	2.26 ± 1.72
Dietary fiber, g/100 g	3.29 ± 2.53	4.51 ± 2.46	7.07 ± 0.5**	5.20 ± 2.33	2.21 ± 1*	4.46 ± 2.46
Protein, g/100 g	8.57 ± 0.77	7.59 ± 1.65	9.156 ± 3.74	11.46 ± 5.30**	7.64 ± 0.93*	9 ± 3.43
Salt, g/100 g	1.14 ± 0.29	1.22 ± 0.26	1.29 ± 0.23	1.24 ± 0.40	1.36 ± 0.22**	1.25 ± 0.29

* indicates a negative deviation from the average value

** indicates a positive deviation from the average value

Based on the one-way ANOVA results, all examined parameters except salt showed significant differences among groups. The calculated F-values exceeded the critical threshold in each case, indicating that the observed variations are statistically significant, while no significant effect was detected for salt (Table 2).

Table 2.

Anova: Single Factor

Parameters	Source of Variation	F	P-value	F crit
Energetic value, kJ/100 g	Between Groups	3.44	0.014*	2.54
Fat, g/100 g	Between Groups	5.09	0.001*	2.53
Fat from which saturated fatty acids, g/100 g	Between Groups	4.31	0.004*	2.54
Carbohydrates, g/100 g	Between Groups	3.71	0.009*	2.53
Carbohydrates of which sugars, g/100 g	Between Groups	1.17	0.335	2.54
Dietary fiber, g/100 g	Between Groups	5.28	0.002*	2.66
Protein, g/100 g	Between Groups	3.48	0.013*	2.53
Salt, g/100 g	Between Groups	0.90	0.468	2.54

* indicate statistically significant differences between bread categories based on one-way ANOVA (p < 0.05)

Box plot analysis

Analysis of the variation in energy content indicated that the wholegrain bread category has the greatest fluctuation. In contrast, the energy content of toast and white breads was measured with the highest precision, showing the smallest variability. Specialty bread demonstrated the second-highest variation among the evaluated categories. Regarding fat content, specialty breads showed the greatest fluctuation, as illustrated in Fig. 1.

Fig. 1.

Box plot analysis of the nutritional values of the studied bread categories. The lower (gray) and upper (yellow) bounds correspond to the second (50th percentile) and third (75th percentile) quartiles, respectively. The red cross indicates the mean value, while the whiskers endpoints represent the minimum and the maximum values

The average energy content per 100 g of bread varied across categories as follows: potato bread (941.06 kJ/100 g) < toast bread (1027.27 kJ/100 g) < specialty bread (1048.27 kJ/100 g) < whole grain bread (1062.91 kJ/100 g) < white bread (1070.40 kJ/100 g).

Regarding fat content, specialty bread exhibited the highest average value (4.47 g/100 g), followed by toast bread (2.86 g/100 g), whole grain bread (1.88 g/100 g), white bread (1.75 g/100 g), and potato bread (1.37 g/100 g). The content of saturated fatty acids follow a similar pattern observed for total fat but differed in their relative proportions. In white bread, saturated fatty acids accounted for 31.2 g/100 g of the total fat, whereas lower proportion were observed in other types of bread: 21.37 g/100 g in toast bread and 19.66 g/100 g in whole meal bread. Potato bread and specialty bread have the lowest relative contents of saturated fatty acids, at 16.07 g/100 g and 14.75 g/100 g, respectively.

Based on the Dixon’s Q test, the minimum energy content was identified as an outlier in all bread types. For fat and fatty acids, the maximum values of whole grain and potato breads were considered outliers. Regarding carbohydrates, except for certain specialty breads, the minimum values were outliers, while the maximum value in whole grain bread was also identified as an outlier. No outliers were detected for sugar content. For fiber, an outlier was found at the minimum value of whole grain bread. Protein content showed outliers at the minimum values of white and potato breads, as well as at the maximum value of specialty breads. Concerning salt content, outliers were observed at the minimum values of toast, whole grain, and potato breads, and at the maximum value of white bread.

Normality test

Normality testing indicated that the significance level for all parameters exceeded 0.05, suggesting that the data were normally distributed. The distributions are visually represented in histograms (Fig. 2).

Fig. 2.

Histograms of the studied bread parameters

Pearson correlation analysis

Pearson correlation analysis was performed on data from 58 bread types to examine relationships among energy, fat, saturated fatty acid, carbohydrate, sugar, protein, and salt content. Although 62 bread types were initially collected, Pearson correlation analysis was performed only on samples with complete datasets. Therefore, bread types with missing values were excluded from the analysis, resulting in a final sample size of 58. A significance threshold of P = 0.05 corresponded to a correlation coefficient of ± 0.2569. The strongest positive correlation coefficient was observed between fat and saturated fatty acids (r = 0.78), indicating a robust association. Significant correlations were also found between energy and fat (r = 0.47) and between energy and saturated fatty acid content (r = 0.42). Additionally, protein content exhibited moderate positive correlation with energy (r = 0.44), fat (r = 0.47), and saturated fatty acids (r = 0.42), highlighting the interconnectedness of these nutritional components across the bread samples.

A strong positive correlation was observed between carbohydrate content and energy content (r = 0.48). In contrast, significant negative correlations were identified for fat and saturated fat content (r = -0.45 and r = -0.34, respectively). No significant correlations were found between sugar content and any of the other studied variables, indicating the absence of a detectable relationship. Notably, salt content exhibited significant negative correlations with both energy (r = -0.28) and fat (r = -0.3), as illustrated in Fig. 3.

Fig. 3.

Pearson correlation coefficient

Regression analysis

Regression analysis was conducted to examined the relationships between carbohydrate, fat, and protein content and energy content individually. Data from all bread samples were included in the analysis, as illustrated in Fig. 4. The correlation coefficient (r) ranged from 0.441 to 0.486 indicating a moderate correlation. The strongest associations were observed between carbohydrate and energy content, as well as between fat and energy content, yielding the highest coefficients of determination. This can be explained by the fact that carbohydrates and fats are the primary contributors to the energy value of bread, providing approximately 4 kcal/g and 9 kcal/g, respectively, and therefore variations in their content have a direct impact on overall energy density.

Fig. 4.

Regression analysis

Principal component and hierarchical cluster analysis

Dendrogram analysis identified two distinct clusters. The first cluster included energy, carbohydrate, and salt content whereas the second cluster comprises fat, saturated fatty acid, protein, and sugar content. The Kaiser-Meyer-Olkin (KMO) obtained value during principal component analysis (PCA) indicated that the nutritional data were suitable for PCA (KMO: >0.5). Data reduction condensed the initial seven parameters into three principal components, which together accounted for 77.75% of the total variance (Fig. 5).

Fig. 5.

Main component and cluster analysis of the examined parameters

Discussion

The results of this study indicate significant differences in the energy, macronutrient, and salt content among the examined bread types, which is consistent with trends reported in previous studies on commercially available breads in Europe and other regions [7, 24]. These differences can be largely explained by variations in ingredient composition, degree of flour refinement, and processing techniques used across bread categories. Potato bread exhibited the lowest energy content, while white bread had the highest, corresponding to a 14% difference. This lower energy density of potato bread is primarily attributable to the incorporation of mashed potatoes, which partially replace wheat flour and increase the moisture content of the final product, thereby diluting the caloric concentration, in line with previous findings [25]. In contrast, the higher energy content of white bread (1070.40 kJ/100 g) can be attributed to the use of refined flour, which possesses a greater caloric value compared to wholegrain flours (1062.91 kJ/100 g) [26].

The observed positive correlation between energy and fat content aligns with reports indicating that higher fat levels, particularly in specialty varieties, substantially increase caloric value due to the addition of oils and fats [27]. Given that fat provides approximately 37 kJ/g, even modest increases in fat content can markedly elevate total energy values. Consistent with this our results also show that specialty breads contained the highest fat content, whereas white bread had the lowest, highlighting the influence of recipe composition on the nutritional profile. Analysis of carbohydrate and protein content revealed that white bread had the highest carbohydrate levels, while specialty breads had the lowest. This pattern reflects the predominance of refined starch in white bread formulations, whereas specialty and whole meal breads often include fiber-rich or protein-containing ingredients that reduce relative carbohydrate contribution. This finding concurs with literature indicating that refined white bread typically contains more simple carbohydrates, whereas whole meal and specialty breads include additional fiber-rich ingredients, reducing their total carbohydrate content [28]. Moreover, whole meal bread had the highest fiber content, reflecting its nutritional advantage and supporting evidence for a lower glycemic index and potential benefits for digestive health [26].

With respect to saturated fatty acids, white bread contained the highest proportion, whereas potato and specialty breads contained substantially lower level. This may be explained by the more frequent use of bakery fats or shortenings in refined bread formulations. This pattern aligns with previous studies indicating that products prepared with refined flour often incorporate fats that increase saturated fat content [28]. The lower saturated fat content observed in specialty breads may reflect the use of unsaturated vegetable oils (e.g., sunflower or rapeseed oil) and alternative ingredients such as seeds, nuts, or legumes, which contribute higher proportions of unsaturated fatty acids to the final product.

The relatively uniform salt content observed across the bread types reflects regulatory efforts to standardize sodium levels in baked goods, addressing public health concerns associated with excessive salt intake and its impact on cardiovascular health [27]. The negative correlation observed between salt and energy content may be partially explained by increased water retention in higher-salt doughs, which can reduce energy density per 100 g of product. Interestingly, a negative correlation between salt and energy content was observed, suggesting that higher salt levels may promote water retention in the dough, thereby reducing overall caloric density [25]. High salt intake is associated with increased risk of hypertension and stroke, and bread is a major contributor to daily salt intake despite recommendations to limit consumption to 5 g/day [29].

Correlation analysis revealed strong associations between fat, saturated fatty acids, and energy, confirming that macronutrients with higher energy density play a dominant role in determining total caloric value. Principal component analysis (PCA) further demonstrated that a large proportion of the variability in nutritional composition could be attributed to a few key factors, emphasizing the influence of ingredient selection and production methods on the overall nutritional profile of bread.

In summary, these results are consistent with existing literature, highlighting the significant influence of ingredient selection, processing methods, and regulatory standards on the nutritional quality of bread. The growing consumer preference for lower-calorie, high-fiber breads reflects a broader trend toward healthier eating habits [28]. Future research should investigate how variation in baking methods and ingredient substitutions can improve the nutritional value of bread while preserving its sensory qualities, including taste and texture.

Conclusion

The nutritional composition of commercially available breads in Romania was systematically evaluated using a variety of statistical approaches, providing a comprehensive assessment of their energy, macronutrient, and salt content. The study aimed to identify significant differences among bread types, offering insights into how ingredients and production processes influence their nutritional profiles.

Comparison of energy content, revealed that potato bread had the lowest average energy value (941 kJ/100 g), likely due to its formulation that includes mashed potatoes, which reduced flour content and increase moisture. In contrast, white bread had the highest energy value (1070.4 kJ/100 g), attributed to its use of refined flour, which is rich in easily digestible carbohydrates. Across all tested bread samples, the average energy content was approximately 1026 kJ/100 g, reflecting a moderate energy density influenced by the diverse ingredients employed in the various bread types.

Dietary fiber content varied considerably among the bread categories. Potato bread had the lowest fiber content, generally below 2.5 g/100 g, likely due to its refined flour base and whole grain content. level, averaging approximately 9 g/100 g. This elevated fiber content reflects the use of whole grain flours, which retain the bran and germ parts of the grain, contributing to increased fiber and nutrient density.

Analysis of fat content indicated that specialty breads, often enriched with seeds, nuts, or additional oils for enhanced flavor and texture, exhibited the highest fat levels among the tested samples, with an average content up to 4.5 g/100 g. In contrast, potato bread had the lowest fat content, averaging approximately 1.4 g/100 g, due to its simple ingredient composition and minimal use of added fats.

Salt content was also assessed, revealing an average of 1.25 g/100 g across all bread samples. This value aligns with regulatory standards designed to limit sodium intake, reflecting industry efforts to standardize salt level in commercially available breads. Minor variations were observed among different bread types, influenced by the recipe formulations and the use of salt as both a flavor enhancer and preservative.

Limitation

In the present study, commercially available breads in Romania were examined, including samples obtained from both the local market in Miercurea Ciuc and online marketplaces.

Authors’ contributions

**Katalin Bodor** : Conceptualization, Methodology, Validation, Formal analysis, Investigation, Resources, Writing - Original Draft. **Zsolt Bodor** : Conceptualization, Methodology, Software, Formal analysis, Investigation, Visualization, Writing - Review & Editing, Supervision.

Funding

The authors declare that no funding was received for the conduct of this research.

Data availability

The datasets generated during and/or analyzed during the current study are available from the corresponding author upon reasonable request.

Declarations

Ethics approval and consent to participate

Not Available.

Consent for publication

Not Available.

Competing interests

The authors declare no competing interests.