J. Martínez-Monzó

Vacuum impregnation and osmotic dehydration in matrix engineering: Application in functional fresh food development

Abstract Health benefits are one of the specific issues that will greatly influence the food industry in the next few years. Functional foods are products that may provide a health benefit beyond the traditional content of nutrients, or through other added physiologically active components (PAC). Fruits and vegetables are increasingly being consumed because of their appreciated nutritional and fresh properties. The enrichment of these products with minerals, vitamins or other PAC can be a good choice to develop functional foods. Vacuum impregnation (VI) allows to introduce controlled quantities of a solution in the porous structure of fruit and vegetable (matrix). This solution can contain PAC, a w or pH depressors, antimicrobials, etc., in order to formulate functional, stable, fresh-like products. The feasibility of VI for a great quantity of fruits and vegetables is discussed by means of analysing their response to VI. Porosity and VI effectiveness of impregnated products were observed by Cryo-SEM. A model to determine the concentration level of PAC in the impregnating solution was established in order to formulate functional foods with different calcium and iron salts which could represent a determined percentage of the recommended daily intake of these minerals.

Development of probiotic-enriched dried fruits by vacuum impregnation

Abstract In this study an attempt is made to combine the beneficial effects of probiotics with fruit and vegetables by applying the vacuum impregnation process. Apple cylinders were impregnated either with commercial apple juice containing Saccharomyces cerevisiae , and with whole milk or apple juice containing 10 7 or 10 8 cfu/ml of Lactobacillus casei (spp. rhamnosus). Impregnated apple samples contained around 10 7 cfu/g. In order to increase stability and to assure fruit preservation, impregnated apple samples were air dried at 40 °C to a water content of 0.037 kg water/kg dry matter and stored at room temperature for two months. The content of L. casei viable cells in dried and stored product was greater than 10 6 cfu/g. This concentration level of probiotics is similar to that in commercial dairy products.

Effect of temperature and air velocity on drying kinetics, antioxidant capacity, total phenolic content, colour, texture and microstructure of apple (var. Granny Smith) slices

The aim of this work was to study the effect of temperature and air velocity on the drying kinetics and quality attributes of apple (var. Granny Smith) slices during drying. Experiments were conducted at 40, 60 and 80°C, as well as at air velocities of 0.5, 1.0 and 1.5ms(-1). Effective moisture diffusivity increased with temperature and air velocity, reaching a value of 15.30×10(-9)m(2)s(-1) at maximum temperature and air velocity under study. The rehydration ratio changed with varying both air velocity and temperature indicating tissue damage due to processing. The colour difference, ΔE, showed the best results at 80°C. The DPPH-radical scavenging activity at 40°C and 0.5ms(-1) showed the highest antioxidant activity, closest to that of the fresh sample. Although ΔE decreased with temperature, antioxidant activity barely varied and even increased at high air velocities, revealing an antioxidant capacity of the browning products. The total phenolics decreased with temperature, but at high air velocity retardation of thermal degradation was observed. Firmness was also determined and explained using glass transition concept and microstructure analysis.

Changes in mechanical properties throughout osmotic processes: Cryoprotectant effect

Abstract In osmotic dehydration of fruits, physical and chemical changes occurring throughout the process provoke changes in the product texture and appearance to a different degree depending on the process conditions and product characteristics. Nevertheless, water content reduction and sugar gain have been observed to have some cryoprotectant effects on colour and texture in several fruits. In this work, the specific influence of osmotic treatments with sucrose solutions at 30°C on mechanical properties of mango, kiwi and strawberry are discussed. The combined effect of blanching and vacuum impregnation is analysed in mango. The influence of osmotic solution concentration and vacuum impregnation on kiwi fruit is discussed and the effect of osmotic dehydration, as compared with air drying is analysed in strawberry. In all cases, changes in mechanical properties of fresh and pre-dehydrated fruits due to freezing–thawing are compared in order to quantify the cryoprotectant effect of the osmotic treatment.

Vacuum impregnation for development of new dehydrated products

Vacuum impregnation (VI) of structured foods implies the partial release of gas from pores and its substitution by an external liquid. Therefore, important changes in physicochemical and structural properties take place in the food and these affect its behavior in drying operations (air-drying (AD) and/or osmotic dehydration (OD)). The adequate control of VI prior to dehydration may be used as a tool both to improve mass transfer and to develop engineered products. In order to evaluate this alternative, the effectiveness of VI as a tool in porous matrix formulation is analyzed. Likewise, its influence on some physical and transport properties of the plant tissue and the relevant changes induced in osmotic and convective drying processes are discussed, since these are probably the most interesting alternative processes to lengthen the impregnated product shelf-life. Improved yield of some dehydration processes, such as fruit candyin, when VI is applied at the beginning, is also discussed in terms of the cell network relaxation mechanism, responsible for hydrodynamic tissue impregnation.

Iron deficiency and iron fortified foods—a review

Abstract Iron is a mineral that is necessary for producing red blood cells and for redox processes. Iron deficiency is considered to be the commonest worldwide nutritional deficiency and affects approximately 20% of the world population. Lack of iron may lead to unusual tiredness, shortness of breath, a decrease in physical performance, and learning problems in children and adults, and may increase your chance of getting an infection. This deficiency is partly induced by plant-based diets, containing low levels of poorly bio-available iron. The most effective technological approaches to combat iron deficiency in developing countries include supplementation targeted to high risk groups combined with a program of food fortification and dietary strategies designed to maximize the bio-availability of both the added and the intrinsic food iron. In this paper, different aspects related to iron-fortified foods is reviewed. These include used iron compounds, considering its bioavailability and organoleptic problems, food vehicles and possible interactions.

Modelling of dehydration-rehydration of orange slices in combined microwave/air drying

Abstract The development of new citrus products, such as dry products for direct use or for rehydration, is interesting to promote their consumption. Combined microwaves (MW)–air (2 m/s, 60 °C) drying of orange slices has been studied in terms of process kinetics and of the rehydration capability as affected by the applied MW power (0, 0.17, 0.36, 0.69 and 0.88 W/g). Drying curves were modelled considering two periods, with different kinetic constants, related with the effective water diffusivity. These constants increased linearly with the applied MW power and, despite the low levels of MW power used, a sharp reduction in drying time of orange slices was obtained. Rehydration behaviour of orange slices was modelled through Pelegs and Weibulls equations. No differences in rehydrating behaviour were observed as a function of the applied MW power. So, the highest level, which was limited to avoid sample browning, will be recommended to reduce the drying time.

Effect of pH on Color and Texture of Food Products

Color and texture are important quality characteristics and major factors affecting sensory perception and consumer acceptance of foods. pH has an important effect on pigments (e.g., chlorophyll, carotenoids, anthocyanins, etc.) responsible for fruit color, vegetables and meat color. Also pH has a great impact on water-holding capacity and tenderness of muscle foods that are improved at acidic conditions below the typical pH of post-mortem. Moreover, during processing of food, the pH value affects many phenomena and processes such as protein properties as denaturizing, gelification, enzymatic activities, growth and mortality of microorganisms, germinating or inactivation of bacterial spores and chemical reactions such as the Maillard reaction. Thus, knowledge of pH effects and its control during processing is necessary to produce safe, high-quality and value-added products. The goal of this paper is to identify the effect of pH on color and texture of food products to show the importance of control this parameter.

Changes in thermal properties of apple due to vacuum impregnation

Abstract Experimental determination and predictive equations are used to evaluate the effect of vacuum impregnation with sucrose solutions on thermal properties of apple samples ( Granny Smith ). Vacuum impregnation (VI) was carried out by immersion of samples in the sucrose solution and applying 50 mbar in the tank for 10 min; afterwards, atmospheric pressure was restored while samples remain immersed for 20 min. Thermal diffusivity was measured in non-impregnated (NVI) and impregnated samples in a transient heat conduction method. Thermal diffusivity changes due to VI were relatively low, whereas conductivity changes, calculated from thermal diffusivity, density and specific heat, showed very important changes. The proposed predictive model allows us to estimate changes in thermal properties due to VI in terms of product porosity and pore distribution and conditions of VI process.

Creativity and Innovation Patterns of Haute Cuisine Chefs

The objective of this article is to analyze the innovation patterns and drivers in culinary activities, especially in the haute cuisine segment. The main aim of this article is to provide an understanding of the innovation processes and context of haute cuisine and innovating chefs. The research is based on a survey of 50 chefs in eastern Spain who manage medium- and high-level restaurants, some of which are Michelin starred.