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The study aims to analyze the composition and mineral profile of oyster shell powder (OSP) and assess its potential as a sustainable source of calcium.

A total of two batches of OSP with different particle sizes had been evaluated for centesimal and mineral composition and microbiological quality. OSP with smaller particles (0.85 mm) was used in the production of bread: standard bread (SB) (0%), fortified bread (FB1) (3%) and FB2 (4%). Centesimal and mineral composition and sensory acceptance had been performed. The internal preference map had been constructed using principal component analysis. The Just About Right data and the influence of sensory attributes on bread acceptance had been assessed by a penalty analysis test.

OSP-0.85 mm had calcium content (478.47 ± 2.37 mg.g-1) lower than OSP-1.00 mm (521.15 ± 0.99 mg.g-1) due to retention of particles. In both batches, heavy metals such as chromium, nickel and copper had not detected. FB1 and FB2 had the best nutritional content compared to SB, with higher calcium content (mg.g-1) 0.69 ± 0.07; 13.76 ± 0.72 and 19.47 ± 1.99 for SB, FB1 and FB2, respectively. The internal preference map showed better acceptance of FB1 compared to FB2. The penalty test showed that this acceptance was penalized (p < 0.05) due to the sandy texture.

The large number of shells generated in the processing of oysters is an environmental problem and generates waste of a natural source of calcium. It has been demonstrated that oyster shell powder can be used as a natural and sustainable source of calcium in bread, requiring further studies to assess the bioavailability of calcium.

The purpose of this paper is to evaluate the chemical and functional composition of acerola, guava and cashew freeze-dried pomaces.

Fruit pomaces were obtained from the pulp juice industrial sector and submitted to freeze-drying. Samples were analysed for composition (macronutrients, micronutrients, moisture and ash), technological attributes (morphological, hygroscopicity, retention of oil and water and solubility), bioactive compounds (total phenolics, flavonoids, proanthocyanins, anthocyanins, carotenoids and ascorbic acid), antioxidant and antimicrobial properties. Total phenolics, brown pigments and antioxidant activity of thermally treated samples were evaluated. Results were presented as mean and standard deviation, and submitted to Shapiro–Wilk normality test, and ANOVA statistical significance follows by Tukey’s post hoc test (p<0.05). Also, Pearson correlation coefficients were used to test the relationship between selected parameters.

Guava pomace had the highest insoluble fibre (40.6 per cent), protein (13.8 per cent) and lipid (9.3 per cent) contents and acerola higher soluble fibre (14.2 per cent) and water and oil holding capacity (12 and 5.4 g/g, respectively). Cashew pomace had higher solubility (45.3 per cent) and hygroscopicity (11.2 per cent). Acerola pomace had the highest phenolic content (5,331.7 mg AGE/100 g), DPPH and oxygen radical absorbance capacity antioxidant activity (63.3 and 756.6 µmol TE/g). Despite of that none of extracts showed antibacterial activity. All pomaces presented good antioxidant activity retention after thermal treatments (> 70 per cent), which might be correlated to thermally induced brown pigments.

This investigation was motivated by the large amounts of pomaces produced by the fruit pulp and juice processing industries, which represents a waste of residual phytochemicals and cause potential environmental problems. Overall, it was demonstrated that freeze-dried acerola, guava and cashew pomaces are promising ingredients for multiple food applications.