Title : Hemp flour as a functional ingredient for partial replacement of nitrites in burgers: Effect on nutrient composition and shelf life characteristics
Nowadays consumers express great concern over the utilization of synthetic preservatives like nitrites in meat products. Consequently, the meat industry is challenged to search for strategies to reduce product supplemented and residual nitrite content to minimize the nitrite intake. Industrial hemp products, like flour, oil, and seeds, have gained attention as potential functional ingredients due to their rich content of bioactive compounds with antioxidant and antimicrobial properties, such as polyphenols and tocopherols. This study examined the effect of addition of hemp flour on chemical and shelf-life characteristics of burgers, following reduction of added nitrites.
Three types of burgers were prepared as follows: HF0 (control) (0% hemp flour, 30 ppm NaNO2), HF4 (4% hemp flour, 15 ppm NaNO2) and HF6 (6% hemp flour, 15 ppm NaNO2). Samples were over-wrapped with oxygen permeable film and stored at 4°C for 3 days as in commercial practice. Burger colour was determined daily using CIELAB L*a*b* colour space. Product composition (moisture, ash, protein and fat contents) was determined according to reference methods. Analysis of the fatty acid composition was carried out with gas chromatography and the following lipid quality nutritional indices, related to healthy fat consumption in meat products, were calculated: atherogenicity index (AI), thrombogenicity index (TI) and hypocholesterolemic/hypercholesterolemic ratio (HH). One factor variance analysis for the comparisons between the three treatments was applied.
Hemp flour had a significant impact on moisture (P<0.05) and ash (P<0.01) contents, but the effect was not uniform across treatments HF4 and HF6. However, there were no significant differences (P>0.05) in protein and fat contents among the three groups. The average composition of burgers across all treatments was 61.19% moisture, 2.25% ash, 14.39% protein, and 15.00% fat, respectively.
Inclusion of hemp flour did not significantly affect the nutritional value of the burgers. No differences in the AI and TI indices were observed among the groups. The average AI and TI values for all treatments were 0.50 and 1.49, respectively. Both indices demonstrated low values, which are advantageous for human health, preferably <3. The HH ratio, with an average value of 3.58, characterizes the impact of fatty acid composition on cholesterol levels, and higher values are considered desirable.
The addition of hemp flour had a significant impact on redness (a*) and color saturation (Chroma) values during storage on day 2 (P<0.01) and day 3 (P<0.001). The average redness and Chroma values on day 3 were 10.16 and 12.00, respectively, for treatments HF4 and HF6. In contrast, the corresponding values for treatment HF0 were 12.65 (redness) and 14.11 (Chroma).
The findings of this study indicate that addition of hemp flour did not significantly affect the nutritional value of burgers. However, instrumentally assessed color changes revealed that incorporating hemp flour, along with the reduction of nitrite content, was not successful in maintaining the color of burgers during storage. Nevertheless, to comprehensively assess the application of hemp flour as a functional ingredient in meat products, further research is needed to investigate the antioxidant profile and the eating quality characteristics along with optimum supplementation levels.