Foam–Mat Dehydration Effect on the Physical Properties, Micronutrient Contents and Sensory Characteristics of Pineapple and Cashew Apple Juice Powder

Abstract

Pineapple and cashew juices were subjected to foam–mat drying to investigate effect on the physical, nutrient and sensory properties of the juice powder. Improved pineapple and Brazilian cashew varieties, soybean and fresh eggs as raw materials were obtained from Anyigba, Nigeria. The fruits were separately prepared into pulpy juice (30 – 35% solids). While soybean and egg were prepared into soy protein isolate and liquid egg albumin respectively as foam agents for each juice at 2 concentration levels (1.0% and 2.0% of pulpy juice). The mixture of juice and foam agent in each case was whipped in food mixer for 10mins, as well as control sample. Stablefoam obtained was dried (60°C) in tray dryer, milled into powder (375  size), packaged (HDPE) and kept at ambient not longer than 2 weeks for physical, nutrient and sensory evaluation and statistical data analysis using standard methods. Foam-mat dried pineapple and cashew powder with added soy protein showed higher hydration capacity (2.0–7.4 mL/g powder) than similar samples containing egg albumin, regardless of the concentration (1–2%), while control samples had highest hydration values (7.4–8.5 mL/g powder). Bulk density (0.30–0.45 g/mL) decreased as foam agent level increased. Pineapple powder has lower reconstitution ratio (powder: water being 1:4) than cashew powder (1:5) which was not affected by the foam agent. Cashew juice powder had lower wettability values (39–40s) than pineapple (44–59s) and therefore cashew powder is more wettable at ambient temperature, 282°C. Similarly, pH values of reconstituted cashew juice (4.4–4.7) were lower than those of pineapple (4.9–5.1). Ascorbic acid contents of 209–230 and 87–112 mg/100 g powder of cashew and pineapple respectively were obtained. The beta carotene contents of 0.19–0.34 and 0.05–0.06 mg/100 g powder for cashew and pineapple respectively were obtained which did not experience any loss. Reconstituted cashew juice powder with added soy protein and control had mean colour scores 5.7 – 6.6. Also, reconstituted pineapple powder samples with egg albumin (2.0%), soy protein (1.0%) and control had similar colour; with mean scores 6.2–7.0, while powder with no foam agent was significantly different (p<0.05). The taste and flavour of foam–mat dried cashew juice (2.0% soy protein) and control were similar, pineapple (2.0% egg white, 1% soy protein) and the control had similar high mean flavour and taste scores (6.2–7.0) and other samples are significantly different (p<0.05). Both cashew powder (2% soy protein) and pineapple (2.0% egg albumin) were adjudged most desirable.