M. Igual

Assessment of the Bioactive Compounds, Color, and Mechanical Properties of Apricots as Affected by Drying Treatment

Consumer acceptance of dried apricots depends on them having an intense orange color, a gummy texture, and a characteristic flavor. In addition, the growing demand for healthy and nutritive foods has increased the interest in this product, as apricot fruits can be considered a good source of phytochemicals, such as polyphenols, carotenoids, and vitamins. Microwave energy may be an interesting drying method, an alternative to conventional sun or hot air drying, with which to obtain dried apricots with good sensorial, nutritive, and functional properties in a shorter time. This paper aims to evaluate the effect of sulfur pretreatment and the drying process (hot air and/or microwaves) on the color, mechanical properties, and ascorbic acid, vitamins A and E, and total carotenoid content of apricot. The obtained results mean that the use of microwave energy, either in combination or not with mild–hot air, may be recommended to obtain dried apricots, without needing to apply sulfur pretreatment.

Effect of Thermal Treatment and Storage Conditions on the Physical and Sensory Properties of Grapefruit Juice

Physical parameters, such as particle size distribution, flow behavior, density, turbidity, and color, were measured and sensory evaluation was carried out to compare the properties of freshly squeezed grapefruit juice with those of juice that has been pasteurized by microwave or by following a conventional heating method. Samples were either frozen-stored or refrigerated. In general, the physical parameters of grapefruit juice were significantly affected by heat treatment, especially in the case of the conventional process. However, from a sensory point of view, pasteurized samples were similar to fresh ones. When frozen, turbidity, particle size distribution, density, flow behavior, and color were stable throughout the studied period, regardless of the pasteurization treatment. During refrigerated storage, the turbidity, particle size distribution, and consistency index decrease. This occurs in a more pronounced way in the case of juice which has not been submitted to a heating treatment, probably due to residual pectin methyl esterase activity. Furthermore, the association between the carboxyl groups of pectin chains and Ca2+ could be responsible for both the subsequent increase in the turbidity of the juice and also the decrease in its density. Throughout the period under study, the smallest color change was experienced by microwave-pasteurized juice. For these reasons, and also due to the reduction in the process time, microwave treatment can be recommended as a method for the pasteurization of grapefruit juice.

Quality and Acceptability of Microwave and Conventionally Pasteurised Kiwifruit Puree

The development and optimisation of food preservation processes seem to be necessary in order to address consumer expectations related to secure, fresh-like foods. To this end, the sensory, nutritional and functional properties must be maximally retained. In order to contribute to the acquisition of knowledge about the adequacy of microwave processing as a means of preserving fruit-based products, the present study compares the impact of microwave heating with conventional thermal processing. The consumer acceptance of fresh and pasteurised kiwifruit puree was studied as was the content of water, soluble solids and bioactive compounds and the pH, consistency, viscosity, colour coordinates and antioxidant capacity, as well as the effect of the thermal treatment on enzyme and microbial inactivation. As bioactive compounds, the content of vitamins C, A and E and the total flavonoid, phenol and tannin content have been considered. As the obtained results show, not only was microwaved puree preferred by consumers, but it also exhibited a superior maintenance of the nutritive and functional properties of the fruit, smaller colour changes and a content of inactivated enzymes and microorganisms equal to or greater than the conventionally heated sample.

Physicochemical and Sensorial Properties of Grapefruit Jams as Affected by Processing

Jam is an effective and tasty way of preserving fruit. Jam processing procedures as well as storage conditions and duration are important factors for jam quality. Traditional jam processing involves the application of severe thermal treatments that imply undesirable changes in the product quality characteristics such as colour, texture, flavour and nutritional and functional value. In this work, osmotic dehydration (OD) and/or microwave energy (MW) was proven as adequate to obtain jam with the typical characteristics of water content, degree Brix, pH and water activity of jam obtained by conventional thermal heating. The sensory evaluation carried out to compare the product showed that samples submitted to more intense heating treatments (conventional or MW) had significantly higher scores in colour saturation, brightness, grapefruit taste and extensibility than OD or OD+MW ones. As deduced from the obtained results, OD treatment prevents grapefruit colour changes, and mild MW heating contributes to increase the consistency and decrease the extensibility of the obtained jam. In this way, OD+MW jam was preferred by assessors mainly due to its higher consistency. The sample obtained by this procedure was stable during storage.

Effect of process technology on the nutritional, functional, and physical quality of grapefruit powder.

The health properties of fruit are widely known. Powdered fruit may be a practical format to be offered to the consumer. Nevertheless, the process used to obtain the powder must ensure the maximum retention of the bioactive compounds and the functional value of the fruit while retaining adequate physical properties. The aim of this study was to compare freeze-drying and spray drying as the drying technologies to obtain grapefruit powder. The obtained results allow freeze-drying to be proposed as a better technology than spray drying in order to obtain a product with a higher content of vitamin C and total carotenoids. Moreover, all of the edible part of the fruit is used in this case, so a greater quantity of healthy compounds is preserved and by-product generation is avoided. Adding about 6 g water, 4 g Arabic gum and 0.6 g bamboo fibre/100 g grapefruit pulp is recommended before freeze-drying.

Stability of micronutrients and phytochemicals of grapefruit jam as affected by the obtention process.

Fruits are widely revered for their micronutrient properties. They serve as a primary source of vitamins and minerals as well as of natural phytonutrients with antioxidant properties. Jam constitutes an interesting way to preserve fruit. Traditionally, this product is obtained by intense heat treatment that may cause irreversible loss of these bioactive compounds responsible for the health-related properties of fruits. In this work, different grapefruit jams obtained by conventional, osmotic dehydration (OD) without thermal treatment and/or microwave (MW) techniques were compared in terms of their vitamin, organic acid and phytochemical content and their stability through three months of storage. If compared with heating, osmotic treatments lead to a greater loss of organic acids and vitamin C during both processing and storage. MW treatments permit jam to be obtained which has a similar nutritional and functional value than that obtained when using a conventional heating method, but in a much shorter time.

Sanguinello and Tarocco (Citrus sinensis [L.] Osbeck): Bioactive compounds and colour appearance of blood oranges

Sanguinello and Tarocco (Citrus sinensis [L.] Osbeck) are the most common and widespread blood oranges varieties in the Mediterranean climate area. Its interest is increasing mainly due to nutritional and organoleptic properties. In this work, three blood orange varieties cultivated in Spain (Sanguinelli, Tarocco Rosso and Tarocco Ippolito) were characterized in relation to physicochemical parameters and relevant bioactive compounds (vitamin C, organic acids, flavonoids and anthocyanins) as well as colour characterization. All samples showed important vitamin C values (higher than 54.9 mg/100 g of edible portion). Flavonoids represent the largest family of phenolic compounds, being hesperidin, the major flavonoid. Ten different anthocyanins were identified in blood oranges, seven cyanidin derivatives and three delphinidin derivatives, being the most abundant cyanidin 3-(6″-malonylglucoside) and cyanidin 3-glucoside. Blood oranges can show an intense reddish colour in peel whereas the pulp has a yellow-orange colour. Overall, these varieties are good sources of bioactive compounds.

Impact of Temperature, Gum Arabic and Carboxymethyl Cellulose on Some Physical Properties of Spray-Dried Grapefruit

Abstract Spray-dried fruit powder may be an interesting alternative for the purposes of promoting fruit consumption among consumers. The use of carrier agents is especially necessary for the production of spray-dried fruit powders. As they may affect some physical properties of the powder, it is important to adjust the amount at which they have to be added to the minimum in order to achieve the necessary effects. The final aim of the study was to identify the most suitable atomization temperature, as well as the optimal concentration of gum Arabic (GA) and carboxymethyl cellulose (CMC) to be used as carriers, in order to obtain grapefruit powder with the maximum dry matter yield (DMY) and porosity, the minimum water content and, simultaneously, with suitable color characteristics. The results of the study don’t recommend the use of CMC and suggest that the best color, the one that corresponds to a free-flowing powder, corresponds to a very luminous one, low in chroma and with a hue that is much more yellow than reddish orange.