THE PRODUCTION OF A DRIED AVOCADO (Persea americana) POWDER

Abstract

This work investigated the technique of vacuum freeze drying of avocado pulp (Persea americana var. Pollock) to produce a dried cake which could be blended into a powder to be used in various food applications. Frozen, mashed avocado pulp samples were dried in a Benhay SB-4 vacuum freeze dryer. For comparison, fresh pulp samples were also oven-dried in a Unitemp drying cabinet at 60°C. Samples were dried until constant weight was achieved after which they were blended into powders and analysed. Analyses included determination of moisture content, water activity, pH and total soluble solids content, colour assessment, proximate analyses, physical properties, rehydration behaviour and a preliminary storage assessment. Drying data was used to generate rate and Moisture Ratio (MR) curves and thin layer models applied to the MR data. The moisture content and water activity values of the fresh pulp averaged 3.16 g H2O/g dry matter (76.0% wet basis) and 0.889, respectively. Samples were successfully dried in the freeze dryer to an average moisture content of 0.02 g H2O/g dry matter (2.1% wet basis) after 72h, and a final average water activity of 0.356. Drying occurred in the falling rate period and the drying rate constant (k1) averaged 0.2496 1/h. The Verma model was found to best fit the Moisture Ratio (MR) data. Compared with oven-dried samples, the freezedried samples dried to lower equilibrium moisture values, did not show any signs of browning and was higher in protein and fat content. The freeze-dried 'cake' was easier to blend to a light, free-flowing powder which easily rehydrated to a form which closely resembled fresh avocado puree. Freeze drying is therefore an attractive option to produce a high-quality Pollock avocado powder, without the use of heat or the application of chemical preservatives to preserve colour.

Status of Avocado Production, Postharvest Handling and Utilization in Kenya

“…Avocado powder is also made from dried avocado halves and shreds. This powder has several advantages over fresh fruit, including being less bulky and retaining its freshness for an extended period of time (Mujaffar and Dipnarine, 2020). Drying techniques such as hot air (oven) drying, heat pump assisted drying, and superheated steam drying have all been thoroughly investigated.…”

“…When avocado powder is combined with water, it instantly transforms into a paste. The powder does not require refrigeration, which makes it more convenient for consumers (Mujaffar and Dipnarine, 2020).…”

Avocado ( Persea americana Mill.) fruit: Nutritional value, handling and processing techniques, and health benefits

“…To enhance the storage period (9 months) with better quality, freeze products are wrapped in packaging using nitrogen inert gas. Freeze‐dried avocado pulp samples blended into powders resulted in a decrease in the water activity and moisture compared with oven‐dried samples was investigated by Mujaffar and Dipnarine (2020). Hence, freeze drying is essential to prolong the avocado shelf life and preserve color without the use of heat/addition of chemical preservatives.…”

Post Harvest Treatments and Shelf Life of Some Tropical Fruit

“…Fruits dried under modern freeze dryer have a longer shelf life without releasing as much of their nutritional content and sensory characteristics [53]. High-quality with preserved color of Pollock avocado powder to be used in various food application was obtained using freeze drying method [54]. Avocado fruit dried using freeze drying method have a shelf life of up to 9 months with exhibited slight changes in nutritional quality and sensorial properties [55].…”