Process Optimization and Kinetic Modeling of Quality of Fresh-Cut Strawberry Cubes Pretreated by High Pressure and Osmosis

Abstract

The quality and preservation of strawberry can be improved by applying mild treatments such as osmotic dehydration and high pressure. The aim was to optimize treatment conditions based on mass transfer, water activity and quality data and model the effect of the process, combined with high pressure, on important quality attributes (sensory indices, anthocyanin, color, etc.) and microbial stability during subsequent refrigerated storage. Strawberry cubes were osmotically treated at preselected conditions (35C, 45 min) (OD) and by in‐pack cold‐pasteurization (600 MPa, 25C, 5 min) (Osmosed and High Pressured, OHP) and stored at isothermal (5–15C) and dynamic conditions (Teff = 7.8C). Kinetics of quality change was studied and modeled as a function of storage conditions. Shelf life was significantly prolonged for both OHP and OD (up to 10 and 4 months at 5C, respectively) compared to untreated samples (7 days at 5C). Samples with L‐cysteine added in the OD solution exhibited an exceptional red color intensity and stability during prolonged storage. Practical Applications Extension of the storage life of the delicate tissue of strawberry is a challenge and can be achieved with the application of mild, nonthermal pretreatments, such as osmotic dehydration (OD) and high hydrostatic pressure (HP). The goal is to optimize the OD operating conditions in terms of water activity and end product quality. This study also provides information on the effects of pretreatments on the main quality attributes and microbial stability during subsequent refrigerated storage. Based on the validated models established, shelf life extension for OD and OD/HP‐treated strawberry cubes can be predicted at any isothermal or dynamic conditions, and be compared to that of untreated fruit samples. It is concluded that the effective combination of OD and HP processing can be used for the production of superior, fresh‐like quality fruit‐cubes, with extended shelf life, stable under chilled conditions.

Osmotic pretreatment for the production of novel dehydrated tomatoes and cucumbers

“…Tomato and cucumber slices were osmotically dehydrated in a muticomponent solution containing (w/w) 50.0-60.0% glycerol, 10.0% maltodextrin, 5.0% trehalose, 5.0% sodium chloride, 1.5% calcium chloride, and 0.2% Citrox © (Tomato or cucumber weight to OD solution weight: 1:3). Glycerol was selected as an effective humectant and water activity lowering agent maintaining or even improving the tissue characteristics of the dehydrated food product (Checmarev, Casales, Yeannes, & Bevilacqua, 2014;Dermesonlouoglou, Bimpilas, et al, 2016a;Dermesonlouoglou et al, 2016b;Moon, Jeya, Kim, & Wand Lee, 2010;Parniakov, Bal, Mykhailyk, Lebovka, & Vorobiev, 2016). The glycerol concentration was used as OD processing parameter: C gly 50, 55, and 60% of the total OD solution.…”

“…Osmotically dehydrated tomato or cucumber slices were kept under water, immediately drained and then weighed. The water (X w ) and solid (X s ) content as well as water activity (a w ) of OD tomato and cucumber slices were monitored during the osmotic dehydration process (X w and X s : 105°C for 24 hr; a w : Aqua LAB 4TEV, Decagon, USA water activity-meter) (Dermesonlouoglou, Bimpilas, et al, 2016a;Dermesonlouoglou, Zachariou, et al, 2016b).…”

“…At pre-determined times (10 min) tomato or cucumber slices were removed and weighed. The water (X w ) and solid (X s ) content as well as water activity of non-dehydrated and osmotically dehydrated tomato or cucumber slices were monitored during AD (Dermesonlouoglou, Bimpilas, et al, 2016a;Dermesonlouoglou, Zachariou, et al, 2016b).…”

The hurdle effect of osmotic pretreatment and high‐pressure cold pasteurisation on the shelf‐life extension of fresh‐cut tomatoes

“…Total aerobic viable count (TVC) and yeasts and moulds were enumerated according to spread plate technique detailed in Dermesonlouoglou et al (2016).…”

“…OD process conditions were selected as optimum based on previous studies (Dermesonlouoglou et al, 2007a,b). The formulation of OD solution was modified to develop a novel chilled osmo-dehydrated tomato product of reduced a w , having extended shelf life (Dermesonlouoglou et al, 2016). Glycerol was used as a humectant to lower a w activity (Moon et al, 2010;Parniakov et al, 2016).…”