EFFECT OF CANDELILLA WAX WITH NATURAL ANTIOXIDANTS ON THE SHELF LIFE QUALITY OF FRESH-CUT FRUITS

ABSTRACT

Films formulated with edible natural waxes extracted from Euphorbia antisyphilitica, and additives Aloe vera (4%), ellagic acid (0.01%) and gallic acid (0.01%) were applied to evaluate their effects on the quality of fresh‐cut fruits stored at 5C and at room temperature (21C) for 6 days. The evaluated characteristics were changes in appearance, weight loss, firmness, color, solid content, pH and water activity (A_w). The additives, combined with the natural wax, demonstrated not to cause apparent damage to the fruits. Generally speaking, the films showed better results in comparison with the control. The treatment with A. vera showed the lowest values in weight loss, water migration, A_w, change in pH and firmness. The ellagic acid coating reduced the color change in a greater proportion. The application of these new edible films to fruits extends their shelf life and increases their antioxidant potential, as well as their nutritional quality.

PRACTICAL APPLICATIONS

Edible films elaborated with a natural wax extracted from Euphorbia antisyphilitica complemented with a potent antioxidant ellagic and gallic acids, and Aloe vera extend the shelf life quality and increase the antioxidant potential, as well as the nutritional quality of fresh‐cut fruits and vegetables, giving way to the possibility of producing nutraceutical products in the form of edible biofilms. Potential applications of these films are very attractive because the components are natural and nontoxic, and they are recommended by their low cost, availability and ease of handling. The possibility of using these films on other food products, not necessarily vegetal in origin, could be assayed.

     

EFFECT OF CHITOSAN COATING ON SHELF LIFE AND QUALITY OF FRESH-CUT MUSHROOM

ABSTRACT

The effect of chitosan coating in fresh‐cut mushroom preservation, including microbiological, enzyme activities, color characteristics and chemical quality attributes, was examined. However, application of chitosan coating to enzyme activity control and quality maintenance of fresh‐cut mushroom was investigated. Fresh‐cut mushrooms were treated with aqueous solution of 0.5, 1 and 2 g chitosan/100 mL, placed in polyethylene bags, and then stored at 4C. Application of chitosan coating delayed discoloration associated with reduced enzyme activities of polyphenoloxidase, peroxidase, catalase, phenylalanine ammonia lyase and laccase, as well as lower total phenolic content. Also, it reduced enzyme activities of cellulase, total amylase and α‐amylase. Microbiological development of the fresh‐cut mushroom treated with chitosan coating was also inhibited compared to the control. The results showed that increasing the concentration of chitosan coating enhanced the beneficial effects of chitosan on extended shelf life and maintained quality of fresh‐cut mushroom.

PRACTICAL APPLICATIONS

In general, the results showed that the application of chitosan coating (with optimum concentration of 2%) of oyster mushroom was observed to greatly inhibit the enzyme activities and lowest microbial count (Y, M and B) during storage at 4C for 15 days. Recommendations for selection of an appropriate chitosan concentration with refrigeration at 4C were given to be a potentially useful tool for extending the shelf life of fresh oyster mushroom. Furthermore, from a technological point of view, it would be conceivable to use chitosan coating in processed mushrooms provided that their safety is assessed and their commercial feasibility is demonstrated. It is concluded that the technique used produced good results; the product showed good quality during processing and storage with respect to microbiological, physical and chemical properties. Also, this technique is important to prevent the decrease in market value and the concomitant economic losses.

     

IMPROVING THE QUALITY AND SHELF LIFE OF TURKISH ALMOND PASTE

Almond paste is an economically valuable product produced from almonds, sugar and a small amount of water. Oxidative rancidity and oil separation are the major problems that are encountered in the paste products affecting the shelf life. Another problem appears to be drying on the surface of the product resulting in poor consumer acceptability. In this study, the formulation of product was altered by adding a commercial stabilizer, antioxidant mixture and maltose syrup to prevent undesirable quality changes during storage at 4C and 30C. Peroxide value, free fatty acid and Rancimat analysis showed that the addition of antioxidant mixture prevented oxidation effectively and improved sensory scores significantly ( P ≤  0.05). Although stabilizer addition had a detrimental effect on the textural properties, samples that have maltose had high sensory scores. The results showed that incorporation of maltose syrup and antioxidant may improve the texture and shelf life of almond paste.

PRACTICAL APPLICATIONS

The available literature on almond paste is mainly focused on the microbiological quality of the product and the prevention of spoilage reactions by modifying packaging materials. However, there is no report on the optimization of the composition to extend the shelf life of almond paste. Turkish almond paste, a healthy and expensive dessert, is a specialty product that is manufactured by using traditional grinding equipment. However, the limited shelf life of this product decreases its export potential resulting in economical losses. Therefore, improved shelf life and quality of the product is of importance from the economical point of view. In our study, we aimed to improve the quality and shelf life of Turkish almond paste by modifying its formulation in order to minimize the undesirable changes that occur during storage.     

THERMOPHYSICAL PROPERTIES OF FRESH AND ROASTED COFFEE POWDERS1

The present work deals with experimental determination of bulk specific heat, bulk thermal conductivity, bulk and true density and moisture content of Columbian and Mexican coffee bean powders. Specific heat was determined by DSC, thermal conductivity by modified Fitch apparatus, density by stereopycnometer and moisture contents by standard vacuum oven method. Specific heat values showed marginal rise over the temperature range (45 to 150C) studied. Thermal conductivity values, determined in the temperature range of 20–60C were not found to have any definite trend with rise in moisture in the experimental range of 4.8 to 9.8% moisture (dry basis). Bulk density of powders varied appreciably (1.298 to 0.882 g.cm^?3), while the change was negligible for true density (1.361 to 1.092 g.cm^?3) with the degree of roasting. Statistical analysis of the data shows the reliability of the experimental determinations. Suitable correlations were developed to determine bulk specific heat and bulk density.     

EFFECT OF STORAGE CONDITIONS ON THE SENSORY QUALITY OF GROUND ARABICA COFFEE

The objective of this study was to determine how long ground coffee beans could be stored at room and freezing temperatures before sensory changes could be detected, and to identify specific attribute changes associated with this storage. Ground beans were stored for 0 (fresh), 1, 2 and 3 weeks at room and freezing temperatures. Coffee was prepared from each of these treatments and difference testing was performed. Paired comparison tests were conducted on the fresh, 1‐ and 2‐week‐stored coffee grounds to examine the attributes of coffee aroma, flavor, bitterness and overall preference. At room temperature storage, results indicated significant (P < 0.05) differences in the coffee prepared from fresh versus the 2‐week‐stored ground beans. Coffee made from freshly ground beans had a stronger coffee aroma, less bitterness and was more preferred compared with the beans stored for 1 or 2 weeks (P < 0.05). At freezer storage, differences were detected between coffee prepared from coffee grounds stored for 1 or 2 weeks. Coffee prepared from grounds stored for 2 weeks had a stronger coffee aroma and was more bitter compared with the other storage times (P < 0.05).