Effect of bamboo fibre and glucose syrup as new ingredients in the manufacture of amaretti cookies

Amaretti”, Sardinian almond based cookies, have a shelf-life of about seven days, due to the quick hardening of the internal moist paste. To improve their quality, two different new ingredients (bamboo fibre and glucose syrup), known as water binding agent, were used separately to obtain two different recipes in addition to the original one. To evaluate their effects, moisture content (wet basis) and aw were measured. Sorption isotherms were determined and texture (by puncture test) and colour (as L* parameter) evolution were monitored. Moreover, a formal sensorial evaluation was carried out. Moisture content and aw evolution indicate that both the ingredients are effective to preserve the softness of the internal paste for a longer time. In particular, after ten days of storage, moisture loss from the internal paste was greater for the traditional cookies (61.2% fall) in comparison with fibre and glucose syrup based “Amaretti” (49.3% and 49.7%, respectively). However, sorption data and puncture test showed that bamboo fibre appears more suitable than glucose syrup to maintain the typical difference between the external dry crust and the moist almond based core, due to an intense water redistribution that take place in the sugar dominated formulation. Moreover, colour analysis evidenced a significant difference between the glucose syrup based recipe (L* ~ 53) and the other ones (L* ~ 75): this added reducing sugar led to a like-burnt colour of the final product. Finally, the most important difference among recipes assessed by the descriptive panel test, concerned the highest stickiness of cookies made using glucose syrup, whereas fibre perception resulted not relevant.