Nutritional Enhancement of Crackers Through the Incorporation of By-Products from the Frozen Pumpkin Industry

Abstract

The agri-food sector faces the challenge of valorizing by-products and reducing waste. The frozen pumpkin industry generates substantial amounts of by-products rich in nutritional value, especially β-carotene. This study evaluates the nutritional and physical impact of incorporating pumpkin pulp flour (dehydrated and freeze-dried) obtained from by-products into cracker formulation. Crackers were prepared by replacing 10% and 20% of wheat flour with pumpkin flour, assessing the effects based on drying method. Physical parameters (expansion, color, and texture parameters) were measured, in the dough and in the baked products. Furthermore, β-carotene content was analyzed by HPLC-DAD, antioxidant capacity was measured with DPPH, ABTS, and ORAC, and total phenolic content was evaluated with the Folin-Ciocalteu method. Proximate composition and mineral content were also analyzed. Additionally, a preliminary sensory evaluation was conducted with 50 untrained consumer judges to assess acceptability of external appearance, texture, and taste. The inclusion of pumpkin flour significantly increased β-carotene content (up to 2.36 mg/100 g), total phenolics, and antioxidant activity of the baked crackers. Proximate analysis showed a marked improvement in fiber content and a slight reduction in energy value compared to wheat flour. Mineral analysis revealed that pumpkin flours exhibited significantly higher levels of K, Ca, Mg, and P, with improved but not always statistically significant retention in the final crackers. Freeze-dried flour retained more bioactive compounds and enhanced color. However, it also increased cracker hardness, particularly with dehydrated flour. Only the 10% freeze-dried formulation showed mechanical properties similar to those of the control. Sensory analysis indicated that all formulations were positively accepted, with the 10% freeze-dried sample showing the best balance in consumer preference across all evaluated attributes. Frozen pumpkin by-products can be effectively valorized through their incorporation into bakery products such as crackers, enhancing their nutritional and functional profile. Freeze-drying better preserves antioxidants and β-carotene, while a 10% substitution offers a balance between nutritional enrichment and technological performance and sensory acceptability.

Keywords: antioxidant capacity; cracker reformulation; functional foods; pumpkin pulp flour; valorization of by-products; β-carotene.

Figure 1

General appearance of the freeze-dried and dehydrated pumpkin, and of the flours, doughs, and crackers.

Figure 2

Chromatic parameters a* (red-green component) and b* (yellow-blue component) of doughs and crackers formulated with wheat flour (control) and with 10% or 20% pumpkin flour, either freeze-dried or dehydrated. Larger symbols represent average values for each type of cracker. D: Crackers elaborated with flour from dehydrated pumpkin; FD: Crackers elaborated with flour from freeze-dried pumpkin.

Figure 3

Antioxidant activity of wheat flour (control) and pumpkin flours (dehydrated or freeze-dried), as well as baked crackers formulated with wheat flour (control) or with varying percentages of dehydrated and freeze-dried pumpkin flours. D: Crackers elaborated with flour from dehydrated pumpkin; FD: Crackers elaborated with flour from freeze-dried pumpkin. Different letters in the columns indicate statistically significant differences between samples (p < 0.05).

Figure 4

Total phenolic content (mg GAE/100 g) of wheat (control) and pumpkin flours (dehydrated and freeze-dried), as well as baked crackers formulated with wheat flour (control) or with varying percentages of dehydrated and freeze-dried pumpkin flours. D: Crackers elaborated with flour from dehydrated pumpkin; FD: Crackers elaborated with flour from freeze-dried pumpkin. Different letters in the columns indicate statistically significant differences between samples (p < 0.05).

Figure 5

Concentration of β-carotene (mg/100 g) in wheat (control) and pumpkin flours (dehydrated and freeze-dried), as well as baked crackers formulated with wheat flour (control) or with varying percentages of dehydrated and freeze-dried pumpkin flours. D: Crackers elaborated with flour from dehydrated pumpkin; FD: Crackers elaborated with flour from freeze-dried pumpkin. Different letters in the columns indicate statistically significant differences between samples (p < 0.05).

Figure 6

Mean sensory scores (±standard deviation) for external appearance, texture, and taste of crackers formulated with 10% or 20% pumpkin flour, either dehydrated (D) or freeze-dried (FD), compared to the control. A 5-point hedonic scale was used, ranging from −2 (“dislike very much”) to +2 (“like very much”). Data were obtained from 50 consumer panelists. Different letters in the columns indicate statistically significant differences between samples (p < 0.05).