A Chromatic Enzymatic Time-Temperature Integrator Device Based on the Degradation of Phenolic Compounds for the Real-Time Prediction of the Quality and Shelf Life of Cherries

The particular characteristics of cherries, such as color, firmness, and palate increase their demand, as does, among other things, their antioxidant properties that benefit human health. However, their high perishability leads to a reduced shelf life and consequently generates undesirable changes in the cherry flow chain. To ensure food quality and safety and prevent food waste, a smart device prototype is proposed. The concepts related to the formulation and design of the enzymatic-type chromatic time-temperature integrator (TTI) device used to monitor the real-time quality of cherries are described. The kinetic parameters for thermal inactivation of cultivar Santina cherries were determined based on the degradation of phenolic compounds that are substrates of the polyphenol oxidase enzyme, whose hydroxylation reaction of a monophenol to o-diphenol leads to the oxidation in o-quinone. The proposed device concept aims to help retailers and consumers decide upon selling and buying according to the remaining shelf life, thus promoting sustainability related to food processes.

Use of residual acid phosphatase activity in heat-processed atlantic cod (Gadus morhua) for estimating thermal load

Farmed Atlantic cod muscle tissue was heated isothermally at temperatures of 56 to 68 degrees C for 15 s to 25.5 min. Extracts from the heat-treated samples were prepared by mixing with Triton X-100 (1:9, wt/wt) and subsequent centrifugation. Residual acid phosphatase (ACP) activity was measured, and the inactivation was modeled in two phases. Mean (+/-standard error) kinetic parameters of thermal inactivation were determined as D(60 degrees C) = 34.93 +/- 2.02 min and z = 22.01 +/- 4.10 degrees C for short heating times and D(60 degrees C) = 3.19 +/- 0.11 min and z = 6.31 +/- 0.51 degrees C for heating times longer than 100 s. The data support the use of residual ACP activity for modeling a 6-log inactivation of Listeria monocytogenes at 60 degrees C but only a 4-log inactivation at 70 degrees C. Extracts prepared from raw muscle and subsequently heated isothermally at temperatures of 54 to 70 degrees C for 2 to 51 min were used to obtain kinetic parameters D(60 degrees C) = 7.98 +/- 1.11 min and z = 6.92 +/- 0.07 degrees C. A short initial drop in ACP activity was observed in raw cod muscle during freezing and cold storage. Subsequently, the activity was stable for 24 months. ACP activity in raw cod muscle did not seem to be influenced by gender, season, or brining with different levels of salt and phosphates. No other factors that could inactivate ACP were found, and usual activity of 2.54 +/- 0.02 Abs/(min*g sample) can be expected in frozen and thawed farmed cod muscle.

Enzyme-electropolymer-based amperometric biosensors: an innovative platform for time-temperature integrators

A novel exogenous time-temperature integrator (TTI) based on an amperometric glucose oxidase biosensor is presented. The TTI consists of the enzyme entrapped within an electrochemically generated poly(o-phenylenediamine) (PoPD) thin film deposited on the interior wall of a platinum (Pt) or a platinized stainless steel (Pt-SS) capsule. After thermal treatment, the TTI is mounted in a continuous flow system and connected to a potentiostat for amperometric detection of residual enzyme activity. A measurement is completed within 10 min. Isothermal treatments were carried out between 70 and 79.7 degrees C. Thermal inactivation of the immobilized enzyme followed apparent first-order kinetics with z values of 6.2 +/- 0.6 and 6.6 +/- 0.8 degrees C for Pt and Pt-SS capsules, respectively. These z values suggest that the proposed TTIs have the potential to assess pasteurization processes that target microorganism such as Listeria monocytogenes and Escherichia coli O157:H7.

Extended study on the influence of z-value(s) of single and multicomponent time-temperature integrators on the accuracy of quantitative thermal process assessment

The possibilities and limitations of single- and multicomponent time-temperature integrators (TTIs) for evaluating the impact of thermal processes on a target food attribute with a Ztarget value different from the zTTI value(s) of the TTI is far from sufficiently documented. In this study, several thousand time-temperature profiles were generated by heat transfer simulations based on a wide range of product and process thermal parameters and considering a Ztarget value of 10 degrees C and a reference temperature of 121.1 degrees C, both currently used to assess the safety of food sterilization processes. These simulations included 15 different Ztarget=10 degrees CF121.1 degrees C values in the range 3 to 60 min. The integration of the time-temperature profiles with ZTTI values of 5.5 to 20.5 degrees C in steps of 1 degrees C allowed generation of a large database containing for each combination of product and process parameters the correction factor to apply to the process value FmultiTTI, which was derived from a single- or multicomponent TTI, to obtain the target process value 10 degrees CF121.1 degrees C. The table and the graph results clearly demonstrated that multicomponent TTIs with z-values close to 10 degrees C can be used as an extremely efficient approach when a single-component TTI with a z-value of 10 degrees C is not available. In particular, a two-component TTI with z1 and z2 values respectively above and below the Ztarget value (10 degrees C in this study) would be the best option for the development of a TTI to assess the safety of sterilized foods. Whatever process and product parameters are used, such a TTI allows proper evaluation of the process value 10 degrees CF121.1 degrees C.

Development characterization and use of a high-performance enzymatic time-temperature integrator for the control of sterilization process' impacts

A small sized single-component enzymatic time temperature integrator (TTI) was developed. It consisted of glass beads coated with Bacillus licheniformis alpha-amylase (BLA) and stabilizing additives in a dehydrated form. Post heating residual enzymatic activity was used as a response property of the TTI. Under isothermal conditions, different batches of the system were characterized by z(TTI)-values around 13.5 degrees C in the temperature range 100-130 degrees C as well as by their ability to provide a response within 5 min after thermal processing. When used under non-isothermal conditions in a model food (silicone spheres), the system allowed to measure process-values (zTTI)F(121.1 degrees C) up to 60 min with an average error of 10.9%. The capabilities of the system were validated in a real solid/liquid food matrix sterilized by retorting. The combination of F(TTI)-values with heat transfer simulations based on finite difference calculations allowed for the determination of process values, which evaluated actual process-values (10 degrees C)F(121.1 degrees C) up to 90 min with an average error of 11.4%. The good performances of the system as well as its easiness of preparation and use, make the latter a valuable biological device for thermal process assessment.