Iron in fortified biscuits: A simple method for its quantification, bioaccessibility study and physicochemical quality

• Biscuits contribute to iron intake in Brazil.
• Biscuit with the highest iron concentration did not present the highest concentration of dialyzed iron.
• Some biscuits were inadequate to consume during the shelf life assessment.

Iron deficiency is one of the most important nutritional problems in the world. The aims of this study were to determine the total concentration of iron in order to evaluate its bioaccessibility in biscuits produced with fortified flour, check the importance of its contribution to the iron intake and monitor physicochemical parameters such as moisture, acidity and peroxide value (PV) during 150 days of storage. The simple and cheap method for iron determination was validated and proved to be adequate. Forty one samples of biscuits including salt water, cream cracker, cornstarch, and buttery biscuits were analyzed and their iron content were 5.3–7.8; 5.0–8.6; 2.5–6.8; and 3.7–5.7 mg/100 g, respectively. The in vitro assay results varied from 1.2 to 4.3 mg/100 g and from 0.2 to 2.1 mg/100 g to solubility and dialysis, respectively. There was significant difference in total, soluble and dialyzed iron content among the biscuit types analyzed. The intake of a biscuit portion can contribute from 5 to 32.5% of the recommended daily intake of iron, depending on the type of biscuit consumed. Lipid content varied from 9.8 to 18.0% for the biscuit types analyzed. In the end of storage time moisture levels increased 1.5% for the majority of samples, besides it was observed that most biscuits showed an increase (around 50%) of titratable acidity after 150 days of storage. The highest PV was 27.8 meq/kg of oil fat for salt and water biscuit (in 90 days of storage), 23.3 meq/kg of oil for cream cracker (in 120 days of storage), 22.6 meq/kg of oil for cornstarch (in 120 days of storage) and 14.1 meq/kg of oil for buttery biscuit (in 60 days of storage), indicating lipid oxidation. Samples with the highest iron and moisture content also presented the highest peroxide value, indicating oxidation. The consumption of biscuits plays an important role in providing the daily requirement of iron intake. However, it is necessary to improve the stability and to provide the desired delivery of nutrients without causing damage to the quality of food and health of the consumers.