CAROTENOID RETENTION AND SENSORY CHARACTERISTICS OF SELECTED VEGETABLES PREPARED BY INDUCTION STIR‐FRYING*

ABSTRACT

The effects of induction stir‐frying on carotenoid retention and sensory characteristics of selected vegetables (carrot, green spring onion, red pepper, snow pea, white spring onion and yellow pepper) were investigated. Cooking times ranged from 4 to 6 min, and cooking yields from 70.9 to 92.0%. The stir‐fried vegetables retained (w/w) more than 85% (mean) of each of their carotenoids (β‐carotene, lutein, zeaxanthin, α‐carotene, β‐cryptoxanthin and lycopene). Over three‐quarters of the 78 consumer panelists reported liking extremely/liking very much or liking moderately/liking slightly the appearance, color, flavor, texture and overall acceptability of carrot, green spring onion, red pepper, snow pea and yellow pepper; whereas, half to three‐quarters reported similarly for white spring onion. Few differences in attribute responses were observed by gender. Induction stir‐fried vegetables had excellent carotenoid retention, and the consumer panelists indicated liking them slightly to extremely.

PRACTICAL APPLICATIONS

This study indicates that vegetables that are cooked by induction stir‐frying retained (w/w) over 85% of their carotenoid content and had sensory characteristics that the consumer panelists liked. Perhaps individuals, specifically college students, might be inclined to consume more cooked vegetables if they liked the appearance, color, flavor, texture and overall acceptability of the vegetables. Consuming vegetables containing higher amounts of the carotenoids may also be beneficial.

     

RETENTION AND BIOACCESSIBILITY OF β‐CAROTENE FROM NATURAL AND SYNTHETIC SOURCES ON BAKING

ABSTRACT

The investigation aimed at determining the retention and bioaccessibility of β‐carotene on baking. Bun was formulated incorporating dehydrated carrot/drumstick leaves/synthetic form of β‐carotene at acceptable levels. The effect of citric acid and turmeric powder on the bioaccessibility of β‐carotene was examined. Buns were analyzed for proximate composition, total and bioaccessible β‐carotene. Incorporation of different sources of β‐carotene did not alter the physical characteristics and proximate composition of the buns. Retention of β‐carotene on baking ranged between 62 and 72% in buns with natural sources and 35% in buns with synthetic source. β‐carotene in the buns showed a high degree of stability on storage. Bioaccessibility of β‐carotene in bun was 5.8% with carrot, 7.1% with synthetic source and below 1% with drumstick leaves. Addition of enhancing components increased the bioaccessibility to a remarkable extent. The study results suggest the possibility of fortifying buns with β‐carotene with enhanced bioaccessibility.

PRACTICAL APPLICATIONS

The study identified natural and synthetic forms of β‐carotene to be incorporated in bun. Bun is the ideal product for fortification; it is easily acceptable by children in whom vitamin A deficiency is highly prevalent. Carrot and drumstick leaves are rich and economical sources of β‐carotene. The selected vegetable sources contain other micronutrients in addition to β‐carotene that will improve the nutritive value of buns. Hence, incorporation of carrot and drumstick leaves in buns will have good market potential. The selected sources of β‐carotene are from easily available natural sources which are economically feasible. The product formulation is well standardized for organoleptic parameters for large‐scale production.

     

OPTIMIZATION OF CORNSTARCH/XANTHAN GUM CONTENT FOR THICKENING OF COCOA SYRUPS

ABSTRACT

Blended cornstarch–xanthan gum systems were optimized for thickening of cocoa syrups. For this purpose the sensory (whole and partial), textural (force of penetration, adhesiveness and stringiness) and rheological properties (flow curves as well as viscosity/time and viscosity/temperature relationships) of cocoa syrups were studied. Flow curves were described by rheological model of Casson, which accounted syrups under study for non‐Newtonian, pseudoplastic and thixotropic fluids. Also models of Weltman and Arrhenius were applied for comparison of obtained data. The areas of thixotropy hysteresis loops were also calculated. Obtained data (sensory, textural and rheological) were used as a base for mathematical calculations. The results were presented in the tables to enable their easier understanding. As a result, optimization of thickeners was achieved – the best ranges of cornstarch (0.45–0.49%) as well as xanthan gum (0.15–0.17%) concentrations in cocoa syrups were selected.

PRACTICAL APPLICATION

The result of this study could be used as a guide for thickening of cocoa syrups by the application of cornstarch–xanthan gum combination, chemically nonmodified thickeners. Mathematical method tried in this study for optimization of thickeners addition could be useful for optimization of the other thickeners and additives employed for different sauces, syrups, dressings, ketchups, mayonnaises, etc.

     

EFFECTS OF AVOCADO FRUIT PUREE AND OATRIM AS FAT REPLACERS ON THE PHYSICAL, TEXTURAL AND SENSORY PROPERTIES OF OATMEAL COOKIES

ABSTRACT

This study was conducted to investigate the effectiveness of partial replacement (50% level) of butter fat by two different fat replacers (avocado puree and Oatrim) on the physical, textural and sensory properties of oatmeal cookies. Compared with the control cookie, both fat‐reduced cookies had greater heights, reduced spreads, increased % moisture loss and higher water activities (P < 0.05). Textural measurements made using the TA.XT Plus Texture Analyzer showed the fat‐reduced cookies to be tougher and less brittle (P < 0.05). Appearance was the only sensory category in which a significant difference was seen (P < 0.05). Both avocado and Oatrim cookies were found to be overall acceptable, and at the 50% level of fat replacement, the total fat content for the avocado and Oatrim cookies decreased by 35 and 39%, respectively.

PRACTICAL APPLICATIONS

When incorporated into an overall healthy diet, reduced‐fat foods made with fat replacers can play an important role in helping consumers reach and maintain their goal of reducing consumption of dietary fat. Results from this study indicate that cookies with acceptable physical, textural and sensory properties could be produced when 50% of the fat is replaced by Oatrim and avocado fat replacers. Dietitians should be aware of such fat replacers. Improved nutritional content, acceptability, ease of preparation and low cost make avocado puree a viable fat replacement option for use in home‐baked products. This data can also serve as a resource to further explore the utilization of Oatrim in developing commercially prepared low‐fat cookies and other baked products.

     

CHANGES DURING FERMENTATION AND PROPERTIES OF SOM-FUG PRODUCED FROM DIFFERENT MARINE FISH

ABSTRACT

Microbiological, chemical and physical changes of Som‐fug produced from six marine fish during fermentation were monitored. During the fermentation (0–72 h) at 30C, the increase in lactic acid bacteria (LAB) count and total acidity (TA) with the concomitant decrease in pH was observed. After the fermentation was completed, Som‐fug samples contained 1.5–7.9 × 10⁹ cfu/g LAB count and TA ranging from 2.00 to 2.28% with the pH range of 4.53–4.60. Trimethylamine N‐oxide content decreased, whereas trimethylamine content increased throughout the fermentation (P < 0.05). Proteolysis of Som‐fug proteins and lipid oxidation occurred during fermentation. As the fermentation proceeded, hardness, adhesiveness, springiness and cohesiveness of all samples increased, and L*, a*and b*values also increased (P < 0.05). Generally, Som‐fug produced from bigeye snapper showed a greater acceptability than those produced from other species. However, its acceptability was slightly lower than a commercial Som‐fug produced from freshwater fish (P < 0.05).

PRACTICAL APPLICATIONS

This research indicates that some marine fish can be used as the raw material for Som‐fug production with the quality almost comparable to those prepared from fresh water fish, which are commercially availalble. Therefore, the improvement of process for Som‐fug production from marine fish should be further conducted to obtain the better quality and higher acceptability. As a consequence, Som‐fug from marine fish with the high nutritive value can become a novel product for the consumers.

     

EFFECT OF ROSEMARY ON THE QUALITY CHARACTERISTICS OF WHITE SHRIMP (LITOPENAEUS VANNAMEI)

ABSTRACT

We assessed the influence of rosemary on some of the quality characteristics of Litopenaeus vannamei shrimp stored under freezing temperature for 180 days. Whole shrimp (WS), peeled shrimp (PS) and PS with dehydrated rosemary (RS) were stored at −28.3 ± 3.8C. Physicochemical and sensorial analysis was carried out. After 180 days, RS had lower pH (P = 0.001) and thiobarbituric acid‐reactive substances (TBARS; P = 0.001) values and higher carotenoids (P = 0.003). WS samples were firmer at 180 days (P = 0.001), although rancid taste and smell were perceived with greater intensity (P = 0.001). The color was more intense in RS and PS than in WS (P = 0.030). Rancid taste was detected in RS only at 120 days at significantly lower intensity (P = 0.001) than WS and PS. Our study suggests that dehydrated rosemary can improve the quality of frozen L. vannamei peeled shrimp.

PRACTICAL APPLICATIONS

Farmed shrimp has gained importance in the global market, and the study of their physicochemical and sensory characteristics is therefore essential. Commercially, shrimp is mainly available in the frozen form, and alternatives to extend its quality during storage are of great interest for consumers and suppliers in the food industry. Dehydrated rosemary can be added to frozen shrimp to improve its quality and maintain the nutritional characteristics during storage.

     

QUALITY AND SAFETY CHARACTERISTICS OF MILK SOLD IN THE STATE OF KUWAIT

ABSTRACT

The food chain operational links for locally produced and imported milk were prepared. Quality and safety assessment of milk were also carried out by collecting raw milk samples from the farms, and pasteurized milk from retail and wholesale outlets. Milk samples were analyzed for pH, titratable acidity, clot on boiling, aflatoxin M1, antibiotic residues, and microbiological quality and safety. Results have shown that the mean pH and acidity of raw milk were 6.83 and 0.180%, while the mean pH and acidity values for local and imported pasteurized milk were 6.9 and 0.170%, and 6.8 and 0.150%, respectively. Furthermore, all raw and pasteurized milk samples were negative for the clot on boiling test and were within the allowable limits for aflatoxin M1 and antibiotic residues. However, raw milk samples collected from the local dairy farms were unacceptable because of the high somatic cell count and high Staphylococcus aureus counts.

PRACTICAL APPLICATIONS

Securing an adequate food supply for the nation has always been the fundamental concern of Kuwait's policy makers. Under local Kuwaiti conditions, with high temperatures over most of the year and the high level of imported products with unknown histories, combined with handling by unskilled labors, food losses can be excessive. This situation creates marketing problems for some of the highly perishable foods like milk. The baseline data of milk losses obtained during this study would help to bring about improvements in storage, handling and distribution practices and develop recommendations for private/public agencies to adopt technologies for improving milk losses. Furthermore, since there are no accurate statistics on milk losses in Kuwait, these primary data could be used to determine the economic values of milk losses in Kuwait.

     

CORRELATION BETWEEN DIELECTRIC PROPERTIES AND FRESHNESS OF LEAF VEGETABLES

ABSTRACT

The correlation between the dielectric properties and the freshness of leafy vegetables was studied to evaluate the quality nondestructively. The dielectric properties were studied on four kinds of leaf vegetables with two plate electrodes during storage at room temperature. The results show that the dielectric constants and parameters for freshness decreased during 3‐day storage of leaf vegetables. A significant correlation between the dielectric properties and freshness of four vegetables was observed. It is possible to evaluate the quality of vegetables nondestructively by determination of dielectric properties.

PRACTICAL APPLICATIONS

Studying the dielectric properties of food is of current interest and may potentially assist the prediction of quality as well as application to the processing and preparation of food. Dielectric technologies are widely adopted and provide unique advantages for predicting storage, electric processing and quality inspection. Innovative assaying of dielectric properties to evaluate the quality of vegetables nondestructively is proposed in this article. Inspection by using the electric physical properties provides methodology for the automation and precision control of food processing.

     

THE EFFECT OF PRETREATMENT OF SHREDDED CELERIAC USING SOLUTIONS OF ENZYMATIC BROWNING INHIBITORS ON THE QUALITY OF MINIMALLY PROCESSED PRODUCT

ABSTRACT

The study investigated the effect of soaking celeriac flakes in solutions containing various concentrations of enzymatic browning inhibitors on the quality of stored minimally processed product. Ascorbic acid (0.2–0.5%), 4‐hexylresorcinol (0.003–0.01%), sodium chloride (0.1–0.5%) and sodium lactate (2–3%) were used as browning inhibitors. On the basis of the conducted tests, it was found that among the applied browning inhibitors, only ascorbic acid had an advantageous effect on the quality of stored celeriac flakes. Along with an increase in its concentration in the solution (0.2–0.5%) used for the pretreatment of the flakes, the value of color parameter a* decreased, while the value of parameter b* increased. At the concentration of ascorbic acid in the solution exceeding 0.25%, flake color in the sensory examination was evaluated as desirable. An increase of ascorbic acid concentration in the solution in the range from 0.2 to 0.4% resulted in a decrease in the total mesophilic and psychrophilic bacteria counts, respectively, by 3 and 1 log cfu/g of the stored product.

PRACTICAL APPLICATIONS

Minimal processing of celeriac provides convenience for consumers and many economic benefits for producers. Minimal processing of celeriac can induce disadvantageous changes in tissue, which may lead to darkening of the flakes and deterioration of product sensory attributes. Moreover, shredded raw material constitutes an excellent medium for the development of microorganisms. This article contains information about the effectiveness of enzymatic browning inhibitors for extending the shelf life of celeriac flakes. We show a range of concentrations of inhibitors, which improve the preservation of color, intrinsic taste and microbial quality of minimally processed celeriac.

     

GLUTEN QUALITY PREDICTION AND CORRELATION STUDIES IN SPRING WHEATS

ABSTRACT

Gluten, “cohesive, viscoelastic, proteinaceous material prepared as a by‐product of the starch isolation from wheat flour” and the storage and dough‐forming protein of wheat flour, is the key to the unique ability of wheat to suit the production of leavened products. Wet gluten was only affected by wheat varieties, while dry gluten was affected by wheat varieties, crop years and their interaction. The wet and dry gluten ranged 8.0–43.13% and 2.58–14.55%, respectively, and were positively correlated with Zeleny value, sodium dodecyl sulfate sedimentation value and falling number. The gluten content was higher in Pavon, SA 42 and Faisalabad 85, while Zeleny value was higher in GA 02 and C 518, resulting in better gluten quality. Zeleny value was negatively correlated with crude protein content (r = –0.1857*). The lowest amount of wet and dry gluten was detected in Triticale and durum wheats as compared to common wheats. Zeleny value and sedimentation value may be used as indicators of gluten content and quality while working on wheats. The information thus collected will be valuable for cereal chemists and wheat breeders for improvements in their future breeding programs.

PRACTICAL APPLICATIONS

This research work will be a breakthrough and helpful for wheat breeders, growers, millers and bakers for their intended uses as every consumer demand specific wheat quality characteristics for their end products.

     

RANKING BEEF MUSCLES FOR WARNER–BRATZLER SHEAR FORCE AND TRAINED SENSORY PANEL RATINGS FROM PUBLISHED LITERATURE

ABSTRACT

Meat scientists have long studied palatability traits of beef muscles, but few characterized numerous muscles over significant numbers of animals. The objective of this project was to rank the major beef muscles for Warner–Bratzler shear force (WBS) and sensory traits based on a comprehensive study of the literature, thereby compiling a large number of observations for each muscle. Muscles with three or more literature sources were ranked for WBS (n = 40), sensory tenderness (n = 14), juiciness (n = 13) and beef flavor (n = 9). Psoas major and infraspinatus were the top ranked for mechanical and sensory tenderness. Semitendinosus, gluteus medius, supraspinatus and pectoralis profundus were major muscles that were among the least tender. The Pearson correlation coefficient of WBS and sensory tenderness means was ?0.84 (P = 0.001). These rankings may be useful as a reference for relative palatability of muscles.

PRACTICAL APPLICATIONS

Knowledge of the relative palatability and rank of individual muscle can serve as a resource at the retail and foodservice establishment to better meet consumers' needs, and through use in educational materials. The popularity and demand of the flat iron (infraspinatus) and petite tender (teres major) steaks are examples of better utilizing and merchandizing the carcass. Furthermore, it can aid processors and product development specialists in identifying additional muscles suitable for value‐added processing and possibilities for acceptable muscle substitutions. Utilization by academics will be through reference for research needs and classroom instruction. The results of this ranking can be utilized by all sectors of the meat industry to ultimately provide an improved product for the consumer.

     

VARIETAL AROMA COMPOUNDS OF VITIS VINIFERA CV. KHAMRI GROWN IN TUNISIA

ABSTRACT

The aroma composition of the grape juice of Khamri, a native variety of Vitis vinifera grown in Tunisia, was investigated for the first time. A total of 27 free and 20 glycosidically bound compounds were identified by gas chromatography‐mass spectrometry. According to the obtained results, the aroma compounds were C6 alcohols, benzene compounds, terpenes, acids and norisoprenoids. On the basis of gas chromatography‐olfactometry, these compounds were grouped, according to volatiles exhibiting the identical odor quality, into 10 groups of the same character (aromatic series) as a way of establishing an aroma profile for the studied variety. The high glycosidically bound norisoprenoid concentrations and the absence of the bound form of the acids were a positive factor for the Khamri variety potential aroma.

PRACTICAL APPLICATIONS

This article aimed on the identification of the unknown Tunisian grapevine varieties that are very well adapted to the arid conditions and that could have a good quality. The discovery of unknown autochthonous grapevine varieties with good aroma and pomological characteristics could be of great importance for the agriculture sector all over the world especially the arid regions.

     

EFFECT OF OSMOTIC TREATMENT WITH CONCENTRATED SUGAR AND SALT SOLUTIONS ON KINETICS AND COLOR IN VACUUM CONTACT DRYING

ABSTRACT

An experimental study of osmotic dehydration (OD) of selected heat‐sensitive products was carried out in a laboratory‐scale vacuum contact dryer. Cubes of potato and apple were examined as model heat‐sensitive objects. Experiments were conducted at different conduction heat input levels with wall temperatures in the range 35–45C under vacuum and also in pure vacuum without any external heat input. Detailed investigations were carried out of OD on drying performance, product temperature and color of the dried product.

PRACTICAL APPLICATIONS

Osmotic treatment of potato and apple samples using concentrated sugar solution shows better osmotic dehydration as well as drying rate in a vacuum contact drying system. This information may help to select the osmotic agent in any industrial application for faster drying rate in vacuum contact drying specially for food products. Moreover this work shows the analysis to find out the starting point of precipitation of osmotic agent inside the products in terms of drying time, temperature and moisture content. This information will be helpful for critical analysis in osmotic dehydration technique which in turns may help for optimum design.

     

RELATIONSHIP BETWEEN RHEOLOGICAL BEHAVIOR AND BOSTWICK MEASUREMENT DURING MANUFACTURE OF KETCHUP

ABSTRACT

The Bostwick consistometer remains an integral part of assessing the consistency of tomato products. For instance, the consistency of lots of tomato paste are designated at the factory by their Bostwick measurement; tomato ketchup is produced to meet Bostwick ranges given in U.S. Standards for Grades. This work addresses the blending of tomato pastes, at different Bostwick readings, for use in the remanufacture of ketchup. For both blends and ketchup, the Bostwick measurement was correlated to rheological parameters measured by two methods: a single‐point method and rotational viscometry. The correlations between the Bostwick measurement and the viscosity were compared with the theoretical prediction based on gravity current flow. The results illustrate that the relationship between the Bostwick measurement and (K/ρ)^?1/(2n+3) provides a means to predict the Bostwick length from at‐line or in‐line viscosity measurements.

PRACTICAL APPLICATIONS

The results of this work provide a means to predict the Bostwick length from at‐line or in‐line viscosity measurements. Specifically, the quantitative relationships presented in the article allow in‐line process control schemes to improve final product quality.

     

SENSORY EVALUATION OF THE TEXTURE OF 49 COMMERCIAL APPLE AND PEAR PUREES

ABSTRACT

The sensory texture of 49 market samples of pear and apple purees were examined by Flash profile and results were treated by Generalized Procustes Analysis. The product set encompassed grocery products, baby foods and drinking snacks. Four main sensory notions were used to describe the texture of this type of products: graininess, viscosity, moisture and grittiness. Pear and apple purees were discriminated by the gritty perception, carried out on the third component. The other three main characteristics were carried out on the first two axes, where six main groups of products were identified. Pear purees were close to baby foods. Thickened baby foods and pear and apple mixtures constituted additional groups. Finally, apple purees were close sensorially, but three groups could be discriminated by grainy and viscous perceptions. The number of products was not an obstacle and the panel managed the task as required.

PRACTICAL APPLICATIONS

Flash profile seems to be a powerful tool to provide a statement of the sensory diversity of a specific market very quickly even when the number of products is quite large.

     

PHYSICAL PROPERTIES OF FISH PROTEINS COOKED WITH STARCHES OR PROTEIN ADDITIVES UNDER OHMIC HEATING

ABSTRACT

The texture, color and microstructure of surimi seafood gels were investigated to determine the interaction effects of fish proteins with starches or protein additives under ohmic heating, and to compare ohmically cooked gels with conventional water‐bath‐cooked gels. Gel properties were affected by the type of additive, concentration and cooking method. The effect of starch on gel texture was more pronounced at low concentrations. Compared to wheat starch, potato starch seemed to slightly improve gel strength; however, it decreased the gel whiteness. All nonfish protein additives resulted in better or equal textural properties of gels, whereas there was a slightly negative effect for gel color. Fast ohmic‐cooked gels mostly exhibited higher gel strength than conventionally cooked gels.

PRACTICAL APPLICATIONS

There is a discrepancy between current gel preparation (slow heating by water bath) and current practice of crabstick manufacturing (fast heating). The use of data generated from slow cooking gel preparation for the manufacture of fast cooking crabstick does not make sense. This study demonstrates how starch and protein additives behave at ohmic heating which mimics the fast cooking crabstick manufacture.

     

CHANGES IN APPARENT VISCOSITY AND VITAMIN C RETENTION DURING THERMAL TREATMENT OF BUTTERNUT SQUASH (CUCURBITA MOSCHATA DUCH) PULP: EFFECT OF RIPENING STAGE

ABSTRACT

The effects that ripening stage have on the apparent viscosity and ascorbic acid retention in squash pulp exposed at cooking process were analyzed. Total soluble solids contents were taken as indicative of ripening degree. In the raw material, water contents ranged from 79 to 96%, but no significant differences were observed among samples grouped as unripe, ripe and overripe. The ascorbic acid contents of pulp increase with increases in soluble solids contents. Pulp from unripe and ripe squash had similar apparent viscosity values; however, lower viscosity values were obtained in pulp from overripe squash. During heat treatment, significant changes in the apparent viscosity values of pulp from unripe and ripe squash were observed. Heat penetration properties of squash pulp indicate correlation between the inverse slope of the straight portion in the heat penetration curves on a semilog plot (fh) and thermal diffusivity values (α) with dry matter content, but no correlation was found with squash maturity degree. High ascorbic acid retention (82%) in pulp held for 30 min at 95C was found independently of squash maturation degree.

PRACTICAL APPLICATIONS

Knowing the rheological behaviour and the ascorbic acid retention of butternut squash pulp during cooking process could be used as a valuable information previously to make decisions for use this crop as a food supply.

     

CORRELATION AMONG METALLIC IONS,PHENOLIC COMPOUNDS AND ANTIMICROBIAL ACTION IN MEDICINAL PLANTS EXTRACTS

ABSTRACT

The extracts of three different medicinal plants –Calendula officinalis L., Maytenus ilicifolia Martius ex Reissek and Cymbopogon citratus (DC) Stapf – obtained with 70% and 95% v/v ethanol had their antimicrobial activity tested against five pathogenic microorganisms. A quantitative analysis of total phenols, flavonoids and mineral species was performed on the extracts using UV‐vis spectroscopy and atomic absorption spectroscopy. Klebsiella pneumoniae showed the greatest sensibility to the extracts tested. The mineral content of the medicinal herbs varied according to the type of plant (Cu = not detected to 10.90; Zn = 0.85 to 10.04; Na = 24.94 to 153.62; Al = 90.04 to 420.39; Mg = 9.62 to 1,129.15; Ca = 7.15 to 167.27 and K = 913.85 to 9,578.94 µg/g); however, the concentration of heavy elements (Pb, Cd and Cr) was null in the extracts. The concentrations of flavonoids ranged from 13.55 to 41.54 mg/g and 92.35 to 518.28 mg/g for phenolic acids.

PRACTICAL APPLICATIONS

The use of plants with pharmacological activities has increased significantly because of their functional properties in the diet for the promotion of human health and antimicrobial effects. Moreover, medicinal herbs play an important role in public health, especially in developing countries. In Brazil, the use of plant extracts in the treatment of certain diseases is very common. This habit can be explained, at least in part, by the belief that herbs with therapeutic effects do not have toxic effects on the organism. In this paper, ethanolic extracts of three medicinal plants, widely cultivated and used by the population of Brazil and worldwide, had their levels of metals ions and total phenolic compounds determined. Antimicrobial activity of the extracts was evaluated against foodborne pathogens or food spoilage organisms or clinically isolates microorganisms.

     

CHARACTERIZATION OF CLOUD COMPONENTS FROM SELECTED TROPICAL FRUITS

ABSTRACT

The composition and characteristics of insoluble fruit matter (IFM) and alcohol insoluble solids (AIS) from banana, mango and orange were evaluated. The galacturonic acid content was significantly higher for mango and orange pectin (6.0%) compared to banana (5%). The degrees of esterification of pectin in AIS were 78 ± 5, 85 ± 6 and 85 ± 2 for mango, orange and banana, respectively. Proteins in the fruit pulps were of low molecular weight (<100,000 Da). The relative proportions of the amino acids in the AIS and IFM were similar, with predominant aspartic acid and low methionine and tyrosine contents. Phenolic compounds were highest in banana pulp (138 ± 2 mg gallic acid equivalent/L = mg GA/L) compared to 102 ± 8 mg GA/L for orange. Phenolic compounds were about 10‐fold less (15 ± 2 mg GA/L) in mango.

PRACTICAL APPLICATIONS

This work has applications to the development of natural clouding agents for juices, juice‐added beverages and protein‐fortified beverages. The chemical analysis provides fundamental information on the potential for stable protein interactions from banana and mango, tropical fruits that are desirable in beverages. Further, the research enhances the potential for value‐added processing of these fruits.

     

EFFICACY OF SOUR WHEY AS A SHELF‐LIFE ENHANCER: USE IN ANTIOXIDATIVE EDIBLE COATINGS OF CUT VEGETABLES AND FRUIT*

ABSTRACT

The effectiveness of edible coatings containing sour whey powder (SWP), compared with soy protein isolate (SPI) and calcium caseinate (CC), in reducing oxidative browning and moisture loss during storage (4C) of cut apples, potatoes, carrots, and onions was investigated. Oxidative discoloration, as determined by the Commission Internationale de I'Eclairage L*a*b* color scale, was significantly reduced (P < 0.05) by treatments over a storage time of 120 min. Loss of lightness was reduced by CC, SPI and SWP coatings. These respectively showed 2.7, 3.3 and 1.5% change of L* value in coated apples as compared with 7.4% in the control. Browning in cut potatoes was significantly reduced from a 145.1% increase in the a* value of the control to 45.9, 37.0 and 30.3% increase for CC, SPI and SWP treatments, respectively. The b* values also reflected the effectiveness of SWP. The moisture barrier effect, tested over a period of 5 days at 4C, was significantly better for the treatments than control. SWP was the best and significantly reduced moisture loss in potatoes and carrots by 40 and 59%, respectively, over control. Cut onions did not show any treatment effect both in terms of off‐color development and moisture loss. The reasons for the excellent moisture barrier and antioxidative property of SWP were discussed.

PRACTICAL APPLICATIONS

Oxidative degradation of fresh fruits and vegetables is a major problem faced by the industry today. Most of the fresh produce is grown in the southwestern part of the country, requiring days of transportation to retail outlets. As the educated consumer is highly health conscious, any effort in extending the shelf life will have to be nonchemical, and preferably natural. Because of small profit margins, the intervention must also be inexpensive. Millions of MT of sour whey, a by‐product of cottage whey manufacture, is wasted because of the lack of appropriate food applications. It is natural, nutritious and presently very inexpensive. Our research investigated the possibility of using this by‐product as a final wash to enhance the so‐called window of freshness of fresh produce and fruit.