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Currently, one of the fastest growing industries in the world is the poultry industry; however, the increase in demand has generated the production of various byproducts, such as bones, and these byproducts have a negative impact on the environment. The aim of the present work was to evaluate the effect of glycation on the increase in antioxidant compounds and the formation of indicators of advanced glycation end products (AGE) in chicken bone hydrolysates; it also aimed to maximize the protein content, degree of hydrolysis and antioxidant content. Through analysis of variance (ANOVA), the content of AGE products (HMF and furfural) formed in the glycation process was analyzed. The chicken bone hydrolysate (CBH) had a protein content of 1.42 g/l, a degree of hydrolysis of 17.2% and an antioxidant capacity of 8334 and 10343 μmol ETrolox/l according to ABTS and ORAC evaluations, respectively. The glycation process increased the ORAC by 6.57%. The presence of hydroxymethylfurfural and furfural was determined in the glycated samples and detected at values between 0.05 and 0.22 and 0 and 0.26 ppm, respectively. In conclusion, hydrolysis and glycation are suitable alternatives that enable the use of chicken bones in producing food ingredients with higher added value.

Pomegranate (Punica granatum) is a non-climacteric fruit with a high antioxidant content in arils and peels, of which 92% are anthocyanins and tannins. However, it is susceptible to chilling injury (CI), a physiological disorder concentrated in the peel, which can affect the organoleptic quality of the fruit. To understand the effects of modified atmosphere and ethylene in responses to stress on the antioxidant quality of the fruit and composition of fatty acids in the peel under CI conditions, the exogenous ethylene treatments (0.5, 1.0, and 1.5 μg L–1), 1-methylcyclopropene (1-MCP; 1 μl L–1), modified atmosphere packaging (MAP: XTend™ bags), combined strategy MAP/1-MCP, and package in macroperforated bags (MPB-control treatment) were evaluated. The assay was performed in cold conditions (2 ± 1°C; 85% RH) to stimulate damage and was sampled for 120 days (+3 days at 20°C). During cold storage, CI symptoms began at 20 days in MPB and at 60 days for all treatments with exogenous ethylene; CI symptoms were delayed up to 120 days in MAP, 1-MCP, and the combined MAP/1-MCP treatment. Damage was concentrated in the peel. Ethylene and MPB-control treatments induced significant electrolyte leakage, lipid peroxidation, and oxidative damage. In contrast, MAP alone or in combination with 1-MCP successfully delayed CI symptoms. However, no significant differences were observed between treatments in fatty acid content, e.g., in the peel, oleic acid, linoleic acid, palmitic acid, but a significant loss was noted after 60 days of storage. Cold storage caused an increase in anthocyanin concentration in the peel and arils, increasing up to 12 times in the peel of the fruit treated with ethylene at the final stage of storage (120 days + 3 days at 20°C), with non-significant differences in the tannin content in the peel. During long-term cold storage of pomegranate, MAP and 1-MCP treatments delay and reduce the appearance of CI symptoms. This long cold storage induces an important decrease in the unsaturated/saturated fatty acid ratio, which is not reversed by any postharvest treatment. A higher unsaturated/saturated fatty acid ratio after 1-MCP treatments showed a protective effect in peel tissues. In addition, it was possible to increase the concentration of anthocyanins in the peel of cold-storage pomegranates treated with ethylene.

Chemical and Bioprocess Engineering Fundamental Concepts for First-Year Students

Freeze-dried berry fruits are generally consumed as they are, whole and without peeling or cutting, as the conservation of their original shape and appearance is often desired for the final product. However, usually, berries are naturally wrapped by an outer skin that imparts a barrier to vapor flow during freeze-drying, causing berry busting. Photo-sequence, experimental, and theoretical methodologies were applied to evaluate the application of CO2 laser microperforations to blueberry skin. Under the same set of freeze-drying conditions, blueberries with and without perforations were processed. The results showed that the primary drying time was significantly reduced from 17 &plusmn, 0.9 h for nontreated berries to 13 &plusmn, 2.0 h when nine microperforations per berry fruit were made. Concomitantly, the quality was also significantly improved, as the percentage of nonbusted blueberries at the end of the process increased from an average of 47% to 86%. From a phenomenological perspective, the analysis of the mass transfer resistance of nontreated fruits, in agreement with reported studies, showed a Type II curvature, with a sharp decrease at low time, followed by a linear increase. In contrast, blueberries with nine perforations depicted a Type III regime, with a saturation curvature toward the time axis. It was demonstrated that CO2-laser microperforation has high potential as a skin pretreatment for the freeze-drying of blueberries.

Page's equation is one of the most successful empirical equations applied to describe water migration throughout food drying processes. However, when analyzed in detail, the mathematical derivation shows a number of inconsistencies. The hypothesis is that the noteworthy success of Page's equation could be explained by its mathematical similarity with the solution of an anomalous diffusion phenomenon. In addition, the extraordinary success of Page's equation has induced other researchers to search for similar equations, but without a phenomenological comprehension. The objectives are: 1) demonstrate that Page's equation presents some inconsistences in its mathematical derivation; 2) demonstrate that the goodness of fit of Page's equation could be explained by its similarity with the mathematical solution of anomalous diffusion model. A comprehensive examination of Page's thesis was performed by analyzing its theoretical development and experimental data. Also, data reported in the literature were analyzed to test the application of Page's equation, Fick's second law and anomalous diffusion model. This study demonstrates that Page's equation was raised from a misinterpretation of Fick's second law. In addition, anomalous diffusion solution has remarkable similarities with Page's equation, mainly because of the inclusion of time exponential parameter (n). One important outcome from the apple drying data was that n must be constant and independent of temperature, given that n is related with the microstructure of the food matrix. In conclusion, the mathematical solution of anomalous diffusion model through the fractional calculus approach may, in part, explain the goodness of fit of Page's equation to drying data.

An interesting potential improvement and challenge in thermal processing of packaged foods is the implementation of simultaneous multi-product sterilization. The aim of this research was to analyze, explore, and optimize simultaneous multi-product sterilization through thermal processing simulation of packaged foods considering both constant (CRT) and variable retort temperature (VRT) profiles. The research was approached through three main tasks, which were defined to discover potential opportunities for simultaneous multi-product sterilization with the attempt to recommend the steps to follow to practically implement it. In most cases, simultaneous multi-product sterilization for CRT processing was feasible, however, it was limited to low retort temperature and restricted to products with similar fh. In contrast, in VRT profiles a higher flexibility for simultaneous multi-product sterilization was found. The opportunity to carry out simultaneous multi-product sterilization provides flexibility to optimize retort utilization, reduce energy consumption, and increase processing plant productivity.

The aim of this research was to investigate the acceleration of brine-salting process of salmon when coupling it with moderate electric field (MEF). Salmon samples were cut into cylinder shape (0.025 +/- 0.001 m diameter and 0.025 +/- 0.001 m height), an

Foods are complex matrices formed by many compounds whose nutritional properties vary when they are mixed. Therefore, the study of ingredients interactions that occur during food formulation is necessary to understand the final behavior of food during digestion. This study examined the effects of sodium alginate mixed with a starch solution (3.0 g/100 g) on glucose release during in vitro digestion. To evaluate the effect of alginate, three concentrations were used (0.5, 1.0 and 2.0 g/100 g), and the in vitro digestion was carried out in two stages: gastric and intestinal digestion. The glucose release was evaluated by colorimetric. In order to understand the behavior of this mixture, complex index (CI), viscosity analysis and differential scanning calorimetry were performed to study the alginate–starch interaction. The results showed that starch hydrolysis began during intestinal digestion, reaching a hydrolysis percentage of 72% during the first 15 min. A significant reduction in starch hydrolysis was observed when 1.0 and 2.0 g/100 g of sodium alginate was incorporated, with hydrolysis percentages around 55% during the first 15 min. The CI varied from 34.34% to 57.11% when alginate was increased from 0.5 to 2.0 g/100 g. Also, the sodium alginate affected the viscosity which can be attributed to a protector role of alginate on the starch granules that diminishes the swelling and amylose leaching. Through this study it was possible to show the importance of molecular interaction between different ingredients used in food formulation and how these interactions can be relevant in the regulation of the glycemic response in carbohydrate based food.

The pomegranate peel, an agro-industrial waste, has a high content of antioxidant polyphenolic compounds with proven health-benefiting and technological properties. Polyphenol stability might be affected by heat treatments that are required during drying. Thus, the aim of this study was to analyze the drying kinetics of pomegranate peel dried by double drum drying and to evaluate its effect on polyphenolic compounds. Pomegranate peel was dried at 100, 110 and 120 °C using a constant clearance (2 mm); the processes were modeled and the physiochemical and antioxidant properties were analyzed. Drum drying at 100, 110 and 120 °C were very fast processes that required short drying times (422 s, 400 s and 257 s, respectively) to reach low moisture contents (5.0, 1.6 and 2.6 g water/100 g peel, respectively). At these short drying times, the total polyphenolic content and antioxidant activity were not significantly decreased at any temperature, and the hydrolysable tannins content was maintained by drum drying at 100 and 110 °C. Thus, the drum drying results demonstrate an efficient alternative to obtain a high quality product from pomegranate peel and thereby reuse and add value to this agro-industrial waste.

The combined effect of ohmic heating (OH) and osmotic dehydration (OD) with vacuum impregnation (VI), on the polyphenoloxidase (PPO) inactivation, physical properties and microbial stability of apples stored at 5 °C or 10 °C was analyzed. The treatments were performed using a 65% (w/w) sucrose solution and with ohmic heating at 13 V/cm at 30 °C, 40 °C or 50 °C for 90 min. Examination of the dehydrated samples showed that the water loss and the solid gain were greater with the OD/OH and VI/OH treatments at 50 °C. PPO was completely inactivated by the OD/OH and VI/OH treatments at 50 °C. There was a correlation between the PPO activity, the color change and the browning index of the treated and stored samples; the values for these parameters were stable when PPO was inactivated. The lowest loss of firmness and color was obtained with the VI/OH treatment at 50 °C. The shelf-life of the apples treated with VI/OH at 50 °C and stored at 5 °C was extended to more than 4 weeks. Therefore, the VI/OH treatment at 50 °C was determined to be the best process for dehydrating apples. Industrial relevance The aim of this research was 1 to study the combined effect of ohmic heating (OH) and osmotic dehydration (OD) with vacuum impregnation (VI) on the polyphenoloxidase inactivation and microbial stability of osmotically dehydrated apples stored at either 5 °C or 10 °C. Two technologies, OH and OD were performed at 30, 40 or 50 °C with an electric field intensity of 13 V/cm and conventional heating for 90 min. The results showed a correlation between the PPO activity, the color change and the browning index of the treated and stored samples; the values were stable when PPO was inactivated. PPO was completely inactivated by the OD/OH and VI/OH treatments at 50 °C. The shelf-life of the apples treated was extended to more than 4 weeks. Under the investigated conditions, VI/OH treatment at 50 °C and stored at 5 °C may be considered the better minimal processing that preserves the fresh-like properties.

Research, innovations and applications in the food industry are always delayed relative to other areas of engineering, in part because modeling, simulation and optimization of food processes face additional challenges due to the nature of biological materials. In addition, researchers and scientists in other engineering fields tend to have better mathematical training in relation to researchers in biological sciences. Our hypothesis is that the diffusion process within food materials which are non-Fickian, that is, anomalous, can be characterized using a fractional calculus formulation. There is currently strong experimental and theoretical evidence that the diffusion process in food materials generally departs from the Fickian diffusion model which comes from the random walk displacement of the diffusants. In biological materials the heterogeneity due to the cellular structure produces regions in which the diffusants can travel anomalous length distances or be stopped in compartments, which produces a departure from the expected results of the random walk, resulting in anomalous diffusion. The introduction and application of fractional calculus to the field of food science/engineering could lead to many uses, primarily in heat and mass transfer processes. Fractional calculus is a powerful tool for solving and understanding complex natural phenomena; therefore, we believe it is necessary to exploit it to the utmost to obtain realistic and practical solutions for the mass transfer phenomena and to demonstrate its potential to other food science/engineering problems.

The combined effect of osmotic dehydration/ohmic heating (OD–OH) and vacuum impregnation/ohmic heating (VI–OH) on physicochemical and quality parameters of strawberry ( a w , color, firmness and microstructure), as well as on microbial stability of storage samples at 5 and 10 °C, was analyzed. Treatments were carried out with a 65% (w/w) sucrose solution at 30 °C, and ohmic heating at 9.2, 13, and 17 V/cm electric field strengths, corresponding to applied voltages of 70, 100, and 130 V. Dehydrated samples showed that water loss was greater in OD–OH treatments at 17 V/cm. The greatest solute gain, least firmness loss and least color loss were obtained in the VI–OH treatment at 13 V/cm. The shelf-life of strawberries treated with VI–OH at 13 V/cm and stored at 5 °C was extended from 12 d (control samples) to 25 d. Furthermore, the VI–OH treatment at 13 V/cm was the best processing condition for dehydrating strawberries.

A critical analysis of the correction factor for the come-up time (CUT) introduced by Dr. C. Olin Ball in his Formula Method for thermal process calculations is described in this manuscript. In the General Method, the effect of the CUT is included in the calculated lethality value as long as numerical integration is carried out over the entire cold spot temperature–time profile from the point when the steam is turned on. The hypothesis of this communication is that Ball’s Formula Method, just like the General Method, includes the effect of the CUT in its calculations. Ball’s Formula Method utilizes a “curve fitting” of the experimental time–temperature data regardless of where the time zero is placed within the come-up time. Therefore, the effect of the CUT is automatically included, because, as in the General Method, Ball’s Formula Method is fitting and managing experimental data. In addition, the regressed time–temperature data used for lethality calculations are exactly the same independent of the time zero location. To evaluate the rationale of the CUT correction factor, computer-simulated time–temperature data and experimental runs were evaluated with time zero shifted to different locations (100, 70, 42, 20 and 0% of the CUT). In addition, the effect of the CUT (shape and length) was studied in terms of FHeating and Tg accuracy compared to the General Method. Independent of the time shift (the location of time zero), the calculations according to the Formula Method for total heating time (Pt + CUT) were always the same. This work states that it is not necessary to shift the location of time zero in Ball’s Formula Method because the calculations over the curve fitting time–temperature data will always include the effect of the CUT regardless of where time zero is placed.

The influence of pulsed vacuum (PVOD) and ohmic heating (OH) on the osmotic dehydration (OD) kinetics and structure of apples was evaluated. Apple cubes (1 cm3) were immersed in a 65 oBrix sucrose solution at 30, 40 and 50 °C for 300 min. The PVOD treatment was conducted at 5 kPa for 5 min, and the OH treatment was conducted at 100 V (electric field of 13 V/cm). The water loss, solid gain, aw, color and firmness were measured, and the microstructure was analyzed using electronic microscopy. The largest water loss was observed with the OD/OH treatment at 50 °C. The greatest amount of solute uptake and smallest firmness loss were obtained with the PVOD/OH treatment at 50 °C. Color differences were associated with the loss of clarity and corresponded to the transparency gain. OH treatments led to changes in the microstructure, cell walls and tissues of the apples due to the electroporation effect, which explained the increase of mass transference. Industrial relevance The aim of this research was to determine the response of apple samples to osmotic dehydration using combined treatments of pulsed vacuum and ohmic heating. Two different technologies, vacuum and ohmic heating at mild temperatures, were used to determine and observe the mass transfer kinetics and microstructure of osmodehydrated apples. In several ohmic heating treatments, the time reduction reached 50% as compared to conventional heating. The increases of temperature, vacuum application and electroporation effect promoted the gain of osmotic solution into the tissue pores, thus reaching equilibrium in the sample with less water loss. Among the investigated conditions, the PVOD/OH treatment at mild temperatures was the best minimal processing method to preserve the fresh-like properties of the apples.

Apples (Malus domestica Borkh.) have been identified as one of the main dietary sources of antioxidants, mainly phenolic compounds. These compounds vary in their composition and concentration, among cultivars and fruit tissues. In this research, the total phenolic content (Folin-Ciocalteau assay), antioxidant capacity (Ferric Reducing Antioxidant Power, FRAP assay) and mineral composition in three fruit tissues (peel, pulp and whole fruit), of apple cultivars commonly used for dried apple production in Chile, were studied. In addition, the physical-chemical characteristics (dry weight, pH, titratable acidity, soluble solids content and color) were also evaluated. The results indicated that the total phenolic content, the antioxidant capacity, and the mineral composition, of peel were substantially higher than those of whole fruit, and pulp for all the cultivars studied. Among cultivars, ’Red Delicious’ apple peels have a significantly much higher content of total phenolic (11.6 mg gallic acid equivalents [GAE] g-1 FW) and a higher FRAP (209.9 µmol Fe+2 g-1 FW). Additionally, a high correlation between total phenolic content and antioxidant capacity was found in all the cultivars and fruit tissues analyzed, except in the apple pulp. On the other hand, the physical and chemical composition differed among cultivars and fruit tissues. In conclusion, our results demonstrated that the total phenolic content, antioxidant capacity, mineral composition, and physical and chemical characteristics vary considerably depending on the apple cultivars and fruit tissues analyzed.

Apples (Malus domestica Borkh.) have been identified as one of the main dietary sources of antioxidants, mainly phenolic compounds. These compounds vary in their composition and concentration, among cultivars and fruit tissues. In this research, the total phenolic content (Folin-Ciocalteau assay), antioxidant capacity (Ferric Reducing Antioxidant Power, FRAP assay) and mineral composition in three fruit tissues (peel, pulp and whole fruit), of apple cultivars commonly used for dried apple production in Chile, were studied. In addition, the physical-chemical characteristics (dry weight, pH, titratable acidity, soluble solids content and color) were also evaluated. The results indicated that the total phenolic content, the antioxidant capacity, and the mineral composition, of peel were substantially higher than those of whole fruit, and pulp for all the cultivars studied. Among cultivars, ‘Red Delicious’ apple peels have a significantly much higher content of total phenolic (11.6 mg gallic acid equivalents [GAE] g-1 FW) and a higher FRAP (209.9 µmol Fe+2 g-1 FW). Additionally, a high correlation between total phenolic content and antioxidant capacity was found in all the cultivars and fruit tissues analyzed, except in the apple pulp. On the other hand, the physical and chemical composition differed among cultivars and fruit tissues. In conclusion, our results demonstrated that the total phenolic content, antioxidant capacity, mineral composition, and physical and chemical characteristics vary considerably depending on the apple cultivars and fruit tissues analyzed.Las manzanas (Malus domestica Borkh.) han sido identificadas como una de las principales fuentes de antioxidantes en la dieta, principalmente de compuestos fenólicos. Estos compuestos varían en su composición y concentración según el cultivar y el tejido del fruto. En esta investigación se determinó: el contenido de fenoles totales (ensayo de Folin-Ciocalteau), la capacidad antioxidante (ensayo FRAP, Ferric Reducing Antioxidant Power) y la composición mineral en tres tejidos del fruto (piel, pulpa y fruto entero) de las principales variedades usadas en la producción de manzana deshidratada en Chile. Adicionalmente se evaluaron las características físico-químicas (materia seca, pH, acidez titulable, contenido de sólidos solubles y color). Los resultados indican que en todas las variedades estudiadas, el contenido de fenoles totales, la capacidad antioxidante, y la composición mineral de la piel fueron substancialmente mayores que los valores obtenidos en el fruto entero y la pulpa. Entre las variedades analizadas, la piel del cv. Red Delicious presentó significativamente mayor contenido de fenoles totales (11,6 mg equivalentes ácido gálico [EAG] g-1 PF) y mayor valor FRAP (209,9 µmol Fe+2 g-1 PF). Adicionalmente, se encontró una alta correlación entre el contenido de fenoles totales y la capacidad antioxidante en todas las variedades y los tejidos del fruto analizados, excepto en la pulpa. Por otro lado, la composición física y química varió. En conclusión, el contenido de fenoles totales, la capacidad antioxidante, la composición mineral, y las características físicas y químicas varían considerablemente, dependiendo de la variedad de manzana y el tejido del fruto analizado.

This research suggests a modification of the adaptive random search method. The proposed modification is based on the utilization of the well-known logistic function or logistic curve in order to improve the random search adaptation characteristics. The algorithm tested results show the advantage of the random search modification over the previous random search organization, especially in the case of solving the multi-modal optimization problems. An interesting and important food industry optimization problem, such as thermal processing, was solved by the new organization of adaptive random search.

This paper describes a simple, practical and efficient (nearly precise, yet safe) strategy for on-line correction of thermal process deviations during retort sterilization of canned foods. The strategy is intended for easy implementation in any cannery around the world. Commercial systems currently in use for on-line correction of process deviations do so by extending process time to that which would be needed had the entire process been carried out at the lower retort temperature reached at the lowest point in the deviation (“commercial” correction). This method of correction often results in extensive unnecessary over-processing with concomitant deterioration in product quality, and costly interruption to the retort loading/unloading rotation schedules in retort cook room operations. These problems are addressed by a novel control strategy that takes into account the duration of the deviation in addition to the magnitude of the temperature drop. It calculates a “proportional” extended process time at the recovered retort temperature that will deliver the final specified target lethality with very little over processing in comparison to current industry practice. Results from an exhaustive “optimization” search routine using the complex method are also reported, that show the proposed strategy will always result in a corrected process that delivers no less than the final target lethality specified for the originally scheduled process.

The objective of this research was to evaluate the diffusion mechanism based on Fick's second law and anomalous diffusion modifying the drying operating conditions temperature (T) and relative humidity (RH) on apple slices (cv. Granny smith). Drying was performed at 30 °C, 40 °C, 50 °C and 30%, 50%, 70%RH based on a 32 experimental design. The drying curves were analyzed to determine the effective diffusion (Deff) using two methods: Fick's second law and anomalous diffusion model based on fractional calculus approach. Our results showed that the anomalous diffusion mechanism fit the experimental data better and revealed a super-diffusive behavior (α > 1). Therefore, Deff values were estimated using the anomalous diffusion model with α = 1.735. With respect to the use of anomalous diffusion model solution based on fractional calculus at different operations conditions allow to get better fitting of drying data than second Fick's law model, even keeping the Arrhenius behavior of Deff with temperature. Practical applications Diffusion process is typically analyzed using models based on Fick's second law. However, several assumptions inherent in Fick's second law are not fulfilled in food materials (e.g., structural heterogeneity). In addition, Fick's second law does not consider structural variations during the drying process, and it is well known that fruits such as apples experience significant structural changes during drying. Fractional calculus is a tool for mathematically representing the anomalous diffusion of solutes whose movements can be faster or slower than postulated in Fick's second law due to food structure. In general, with second Fick's law model not good fitting to data are obtained, therefore the prediction capacity of the model is limited. Based on this, anomalous diffusion solution based on fractional calculus was applied. The results showed good fit the data to the model, and also by the time exponent (α) is possible to identify the kind of diffusion process.

Scientific evidence has shown that high sodium consumption from salt can lead to arterial hypertension. Most salt is consumed through processed food to enhance flavor or to increase water retention in the case of processed meats and seafood. In the processing of fish, such as salmon, considerable organic waste is generated that could be reused in the form of a protein hydrolysate if it could serve a useful purpose. The hypothesis of the work presented in this paper was that protein hydrolysate made from salmon waste could replace salt for the purpose of enhancing water retention in the (Sous Vide) processing of salmon filets. The main objective of this research was to observe the effect of different combinations of protein hydrolysate and salt concentration on the drained weight of the final product, and to determine that the results obtained were statistically and economically significant. Response surface methodology was used to study the simultaneous effects of different combinations of protein hydrolysate and salt concentrations on resulting drained weight. A 4x4 factorial design was used, where concentrations of protein hydrolysate were 0%, 7%, 10% and 14%, while salt concentrations were those established by the U.S. Department of Agricultural for salmon as regular, low, very low and no added sodium (1.9%, 0.6%, 0.2% and 0%, respectively). Results showed that the combination of 14% hydrolysate and 0.2% salt achieved nearly the same level of water retention as the standard industry practice of adding nearly 2% salt. This could mean that processors could reduce current levels of salt addition by 90% without compromising process performance, nor color or texture in the final product.

A vapor pressure correlation based on Antoine's equation was proposed for methyl jasmonate. Equilibrium data was obtained in the range of 3-100 degreesC and analyses were performed with GC-MS by solid phase microextraction technique. The correlation gives an acceptable extrapolation for the boiling point at atmospheric pressure, allowing evaluation of vapor pressure at temperatures usually found in food and agricultural process applications. (C) 2003 Elsevier Science Ltd. All rights reserved.

Multiway principal component analysis (MPCA) and multiway partial least squares (MPLS) were applied to unfolded fermentation data, and compared for early recognition of problematic behavior in wine fermentations, such as late onset, slow or stuck (premature termination of fermentation). Information from 17 industrial wine fermentations (batches) were used, consisting of measured values for 32 variables, consisting of sugars, density, alcohols, organic acids and nitrogen compounds (including all amino acids). Curve smoothing and curve fitting techniques were applied as necessary pre-treatment of the data. Then, MPCA and MPLS were applied to four different data sets with different combinations of variables to identify the principal components responsible for the problematic behavior. Density, sugars, alcohols and selected organic acids were identified as the principal components. The MPCA application detected only 67% of problematic batches in the data sets after 72 h into the fermentation process. Whereas, the MPLS application was able to predict all of the problematic batches (100%) using the same variables and at the same time into the fermentation process. The ability to identify a problematic fermentation within 72 h can have significant economic impact on operating costs in a commercial winery.

Agro industry is a very important industrial sector worldwide, especially for countries like New Zealand and Chile. The main objective of this research was to propose a new economic evaluation procedure to optimize the design and operation of multiple effect evaporators and compare it with the traditional chemical engineering approach of total cost minimization. The proposed strategy incorporates a quality factor expressed as a function of lycopene concentration on the final product to find the optimal number of effects and operating conditions through the maximization of the net present value. The mathematical model was implemented using Microsoft Excel and considered mass and energy balances, specific relations for tomato concentration and a first order degradation kinetic for lycopene. The results indicate that when augmenting the capacity of the evaporation system of 5 effects from 50 to 75 Ton/h, the lycopene retention increases from 95.25% to 96.27%. When evaluating the system through the logic of the total cost minimization, an optimum of 4 effects is found, but when evaluating the system using the maximization of the Net Present Value including lycopene as a quality parameter, the optimum is 3 effects. It appears of extreme relevance to consider quality as an intrinsic and integral part of the process design, as it will then be possible to identify several potential improvements in different food processes.

The increase in the levels of psychotropic bacteria in the raw milk during the refrigeration period, could lead to the production of heat-resistant enzymes responsible for the deterioration of long-life industrial dairy products. Pseudomonas fluorescens is the psychotropic bacteria most commonly found in milk in Southern Chile. In the present work the enzymatic proteinases extract of cultures of Pseudomonas fluorescens RV10 at 6 degrees C in raw milk just milked were purified. It was found that the proteases corresponds to a protein with a molecular mass of 49.5 kD, that presents heat resistance and rapidly attacks the k-casein continuing with the b-casein. It is possible to conclude that storage of the milk for long-life products at 6 degrees C is risky, as it causes the loss of quality for the proteases of psychotropic bacteria.

A mathematical model for gas diffusion processes in MAP systems was built. The model was applied toMAP systems containing CO 2 , O 2 , and N 2 with nonrespiring foods. The validation study was done with gelatin, andsimulation trials were carried out utilizing Hake ( Merluccius australis ) fillets. Experimental results confirmed theproposed mathematical model and its numerical solution. The prediction errors obtained in the validation studywere under 5%; the same was true with the simulation trials whose errors were always lower than 5%. Both thesimulation trials and validation study demonstrated that MAP systems reach equilibrium after a short period of timeif film permeability is low.Key Words: modified atmospheres, mathematical model, nonrespiring foods Introduction T ECHNOLOGIES THAT MODIFY FOOD ENVIRONMENTS FOR preservation purposes have been extensively studied inthe past two decades. Although the preservation action of car-bon dioxide has been known since the last century (Parry1995), its commercial application only started when the de-mand for natural foods rose in the past 20 years. Even thoughtechnological advances have been made, most of the modifiedatmosphere packaging (MAP) development has been empiri-cal. As a result, research studies are not fully reproducible. Re-sults are specific to the experimental conditions and not ex-tendable to other applications. The increased consumerawareness of food quality has emphasized the need to opti-mize the MAP system. Computer-aided methods offer the op-portunity for industrial food processors to design more effi-cient processes in order to manufacture products of the high-est possible quality. Thus, for an adequate design and optimi-zation of MAP systems, the availability of quantitative toolsbased on mathematical models is necessary.Research studies using mathematical modeling for MAPsystems have centered their efforts on postharvest fruitsand vegetables (Lee and others 1991; Morales-Castro andothers 1994; Fishman and others 1995; Talasila and Cam-eron 1997; Lakakul and others 1999). Some models havebeen proposed for simulating gas concentration evolutionover time. These models account for fruit or vegetable res-piration and gas transport across the films. Some of thesemodels are limited to estimating the equilibrium concen-tration inside the package. This advance, although valid, canonly be used for respiring biological materials and cannotbe used for products where the gas diffusion is the maintransport mechanism. Quast and Karel (1971), in their clas-sic paper, studied diffusion and oxidation of O

The objective of this research was to develop, and experimentally validate a fully mathematical model, to predict mass transfer phenomena in Pacific Hake (Merluccius australis) packed in refrigerated modified atmosphere. A mathematical model to predict mass transfer of CO 2 , O 2 , N 2 and water vapor was developed and validated. The diffusion model was developed utilizing Fick's second law, considering fish fillet as an infinite slab and applied to Pacific Hake (lean fish species) under refrigeration conditions. CO 2 diffusivity of Pacific Hake was determined by an inverse procedure at OC and resulted in a value of 5.19 x 10 -10 [m 2 /s] that is in accordance with values reported in the literature. However, postmortem variations of pH could affect solubility and diffusivity of CO 2 in fish muscle. L'objectif de cette recherche est de developper et de valider un modele mathematique complet pour predire le phenomene de transfert de masse de CO 2 , N 2 et O 2 dans du merlu (Merluccius australis) emballe sous atmosphere modifiee refrigeree. Le modele de diffusion est developpe en utilisant la seconde loi de fick et le coefficient de diffusion par une procedure inverse a 0°C. Cependant, les variations postmortem du pH peuvent affecter la solubilite et la diffusivite du CO 2 dans la chair de poisson.