Studying the effect of tomato pomace incorporation on physicochemical, nutritional and storage characteristics of corn-based extrudates using response surface approach

PurposeThe present research was envisaged with an aim to optimize the system and the product responses for the development of tomato pomace-incorporated corn-based extrudates employing central composite rotatable design and determine its proximate, lycopene, consumer acceptability and storage studies.Design/methodology/approachLycopene-rich extrudates were developed from corn flour blended with different levels of tomato pomace. The independent extrusion variables, namely, feed composition (95:5 to 75:25), feed moisture (12–20%), screw speed (200–600 rpm) and barrel temperature (125–185 °C), were studied to determine their influence on dependent variables, namely, specific mechanical energy, hardness, water solubility index, lateral expansion, water absorption index, bulk density and color.FindingsAll of the quality parameters were significantly (p < 0.05) influenced by independent variables. The regression models obtained for all the responses showed high coefficients of determination (R2 = 0.85–0.95). The optimum conditions for the development of tomato pomace-incorporated corn-based extrudates were feed composition (90:10), feed moisture (14%), screw speed (300 rpm) and barrel temperature (170 °C). The moisture, fat and carbohydrate contents of the extrudates were significantly reduced, whereas protein, ash and fiber were significantly (p < 0.05) enhanced after the incorporation of tomato pomace. Aluminum laminates were found to be the suitable packaging materials for extrudates for a period of 120 days in comparison to high-density polyethylene packages.Originality/valueAs far as the authors could possibly know, scanty literature exists wherein the tomato pomace has been utilized for the development of lycopene-rich corn-based extruded snacks. Such extrudates with significantly higher fiber and lycopene contents than corn flour will serve as a suitable alternative for the development of shelf-stable ready-to-eat extruded snacks.

Innovative Application of Phytochemicals from Fermented Legumes and Spices/Herbs Added in Extruded Snacks

A trend related to adding legume seeds to various products has been observed. This work aimed to use fermented red bean/broad bean seeds and their hulls to produce extruded snacks with more beneficial nutritional properties and good sensory quality. Extruded snacks containing fermented ground seeds (50%) or hull (10%) of red bean/broad bean and corn grits with the addition of selected herbs/spices (0.5%) were prepared. The chemical composition, phenolic profile, antioxidant activity, and sensory quality were analysed. The results showed that the protein content ranged from 9 to 22.9 g 100 g−1, phenolic compounds ranged from 3.97 to 12.80 mg 100 g−1 (with the addition of herbs/spices, even up to 62.88 mg 100 g−1), and antioxidant activities ranged from 4.32 to 10.23 Trolox g−1 (ABTS assay), depending on the type of fermented materials. The addition of ground seeds/hull did not influence the consumer desirability, whereas the addition of selected herbs/spices, particularly lovage, increased it. The application of fermented red bean and broad bean seeds and their hulls, as part of the assumptions of the planetary diet, enabled enrichment of extruded corn products, which are often consumed by vegans and vegetarians, with nutritionally valuable ingredients.

Response surface analysis and process optimization of non-cereal (elephant foot yam, taro and water chestnut) snacks

The present study was conducted to develop non-cereal starch extruded products. The effects of feed moisture (15-21%), temperature (130-170 °C) and screw speed (120-160 rpm) were evaluated on the physical and functional properties of extruded snacks using response surface methodology. Feed moisture and screw speed increased the bulk density and hardness of extruded snacks. Significant decreases in water absorption index and increases in water solubility index were observed with increases in extrusion temperature. The best conditions were determined by numerical optimization. The optimized value for non-cereal snacks for feed moisture is 18.22%, temperature 155.96 °C, screw speed 142.75 rpm and, desirability is 0.75. Verification of results showed decent agreement between the responses of experimental values at certain optimum conditions and the predicted values.

Textural properties of extruded snack products formulated with deboned poultry meat and brewer’s spent grain

The incorporation of protein- and fibre-rich ingredients into starch-based extruded snacks is of interest for obtaining healthy products. However, development of this type of product has been limited, since protein and dietary fibre have negative effect on textural properties of extruded snacks. In the present study, response surface methodology was used in order to evaluate the effect of different ratios of mechanically deboned poultry meat (MDPM) and brewer’s spent grain (BSG), as well as screw speeds, on hardness, firmness and crispiness of the extrudates produced. Regression analysis showed that BSG and screw speed had significant effects on all textural parameters, while MDPM had a significant effect only on the crispiness of snack products.

Nutrient-Dense Shelf-Stable Vegetable Powders and Extruded Snacks Made from Carrots and Broccoli

Perishable fresh vegetables that do not meet cosmetic standards and by-products of processing are currently wasted. Broccoli and carrots were selected as model vegetables to demonstrate that they can be converted into nutrient-dense and shelf-stable food ingredients and formulated into convenient ready-to-eat snacks. Broccoli powder was a rich source of protein (30%) and dietary fibre (28%). Carrot powder had lower protein (6.5%) and dietary fibre content (24%) and was higher in sugar (47%) compared to broccoli powder (21%). Compared to the whole-vegetable powders, pomace powders were richer in fibre but had lower levels of total carbohydrates. There was a reduced expansion of extruded snacks with increasing levels of the vegetable component in the formulation. Processing and storage for 12 months at 25 °C or 40 °C resulted in changes in the measured soluble phenolic content. Changes during storage were dependent on the temperature and time. The changes may be in part due to the changes in the material properties of the matrix as a consequence of processing and storage, which affect extractability. The conversion of perishable vegetables and pomace into shelf-stable nutrient-dense food ingredients and products will reduce food loss and waste in the vegetable industry.