The objective was to estimate quality changes in Chilean sea cucumber (Athyonidium chilensis) using sun drying (SD), freeze‐drying (FD), and combined electrohydrodynamic and FD (EHD‐FD) at 30°C, packaged in low‐density polyethylene packages and stored at 30%, 50%, 70%, and 90% relative humidity (RH) for 3 mo. Water activity (Aw) content, moisture content (MC), total volatile base nitrogen (TVBN), hardness, and springiness were monitored. The Weibull model was applied to determine kinetics and predict shelf life. Initially, SD exhibited lower quality. All indicators increased over time at 70% and 90% RH, regardless of the drying treatment. The Weibull model was well fitted with all TVBN data, the indicator selected for shelf life. The shortest shelf life during storage was for SD. As for FD and EHD‐FD, the most important difference occurred at 50% RH with 52 and 44 days, respectively.
Practical applications
Chilean sea cucumber (A. chilensis) has a high nutritional value. Its properties are reduced when it is sun‐dried. Therefore, other drying methods such as freeze‐drying and electrohydrodynamics as pretreatment combined with freeze‐drying are used to improve its quality and nutritional parameters and durability. The study of accelerated shelf life at different levels of relative humidity of Chilean sea cucumber offers tools for producers given that the Weibull model can predict the durability of the product and the preservation conditions of dry products over time.
Maqui (Aristotelia chilensis (Mol.) Stuntz) is a Chilean berry rich in antioxidants, which are mostly found in the pulp and skin of the fruit. The objective was to evaluate the cryoconcentration process by centrifugation–filtration as a simultaneous, efficient, and innovative method to increase the content of thermosensitive bioactive compounds of aqueous maqui extract. Cryoconcentration separated the concentrated solute from the aqueous maqui extract with an efficiency of more than 95%; it increased the content of total polyphenols and total anthocyanins and antioxidant capacity by 280%, 573%, and 226%, respectively. Although the concentrates obtained by evaporation at 50, 70, and 80 °C increased the content of bioactive compounds, they did so in a lower percentage than the cryoconcentrate. Furthermore, cyanidin 3,5-diglucoside was degraded at 70 and 80 °C. In conclusion, cryoconcentration by centrifugation–filtration as a simultaneous process efficiently separates the solutes from the frozen matrix of aqueous maqui extract, and it maintains and increases the contents of polyphenols and anthocyanins and antioxidant capacity. This method is recommended for concentrating natural berry extracts with thermosensitive compounds.
The objective of this study was to evaluate the effect of cryoconcentration assisted by centrifugation-filtration on the bioactive compounds and the microbiological quality of aqueous maqui (Aristotelia chilensis (Mol.) Stuntz) and calafate (Berberis microphylla G. Forst) extracts pretreated with high-pressure homogenization (HPH). Aqueous extracts were prepared from fresh fruits which were treated with HPH (predefined pressure and number of passes). The best pretreatment was determined by aerobic mesophilic, fungal, and yeast counts. Treated extracts were frozen at −30 °C in special tubes and centrifuged at 4000 rpm for 10 min to obtain the cryoconcentrated product. The optimal pretreatment conditions for HPH were 200 MPa and one pass in which the extracts exhibited no microorganism counts. Cryoconcentration by freezing and subsequent centrifugation-filtration in a single cycle showed high process efficiency (>95%) in both soluble solids and bioactive compounds (total polyphenols and anthocyanins) and antioxidant capacity of the fresh fruits and extracts. The HPH treatment and subsequent cryoconcentration assisted by centrifugation-filtration is an efficient technology to obtain concentrates with good microbiological quality and a high content of bioactive compounds.
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