Guava Nectar Research Articles

Changes in guava (Psidium guajava L. var. Paluma) nectar volatile compounds concentration due to thermal processing and storage

Guava nectars were formulated for approximately 10, 12, or 14 ºBrix, with 40% guava pulp. Sodium benzoate, 500 mg.kg-1 was used as preservative. The Brix value was adjusted with saturated sucrose syrup. The guava nectar was pasteurized (85 ºC/42 seconds) in tubular heat exchanger and then hot filled in 500 mL white glass bottles. The products were stored either at room temperature (25 ± 5 ºC) or refrigerated (5 ± 2 ºC) under fluorescent light exposure and analyzed on the day after processing (time zero) and also 40, 80, and 120 days of storage. Eight compounds were identified and quantified by Gas Chromatography (GC) -Mass Spectrometry (MS): hexanal, (E)-hex-2-enal, 1-hexenol, (Z)-hex-3-enol, (Z)-hex-3-enyl acetate, phenyl-3-propyl acetate, cinnamyl acetate, and acetic acid. There was no significant effect of thermal treatment on the volatile compound concentrations, except for a significant decrease (p = 0.0001) in hexanal and (Z)-hex-3-enyl acetate (p = 0.0029). As for the storage time, there was a much greater decrease in the esters contents, such as (Z)-hex-3-enyl and phenyl-3-propyl acetates. Cinnamyl acetate had the greatest decrease over storage time. Refrigeration was better than room temperature for guava nectar volatile compounds stability over storage time, mainly for esters compounds, which are important for the product aroma and flavor

IN VITRO ANTIOXIDANT CAPACITY, PHENOLIC, ASCORBIC ACID AND LYCOPENE CONTENT OF GUAVA (Psidium guajava L.) JUICES AND NECTARS

capacity in vitro of three different brands of guava nectars and juices, through free radicals scavenging methods, 1,1-diphenyl-2-picrylhydrazine (DPPH) and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid (ABTS.+), and its correlation with the total polyphenolic content, total lycopene and ascorbic acid. Brands revealed statistical differences (p£ 0.05) in antioxidant capacity, ranging from 1.9 to 7.7 molTE/mL. Antioxidant capacity presented positive correlation for ascorbic acid content and polyphenolic compounds, being relatively low for the lycopene. Different process can influence the content of these compounds as well as interfere in their antioxidant capacity. The control of the production process is important to add value to guava products and fulfill the new tendency of the market.

Tropical Fruits and Nectars Typically Consumed in Latino Communities Are Excellent Sources of Vitamins A, C and Other Nutrients

Latinos are the largest minority group in the U.S. The Nutrient Data Laboratory (NDL) is sampling and analyzing foods commonly consumed by Latin Americans in order to improve the quality and quantity of data on ethnic foods in the USDA National Nutrient Database for Standard Reference (SR). Guanabana, guava, mango, and tamarind nectars were sampled from retail stores using NDL’s National Food and Nutrient Analysis Program’s (NFNAP) nationwide, probability-based method. Nectars were sent to qualified labs for analysis of proximates, sugar, fiber, vitamins, minerals, and carotenoids. Findings include the following per 1 cup (251 ml): guava nectar, 10% DV for fiber; and mango nectar, 35% DV for vitamin A. All nectars are excellent sources of vitamin C (30-82% DV). NDL and Minnesota’s Nutrition Coordinating Center created a list of tropical fruits typically consumed in Latino communities. The NFNAP sampling method was not feasible due to the low probability of finding these fruits in retail stores. Cherimoya, jackfruit, mango, papaya, and mamey sapote were purchased from U.S. wholesalers, then composited and analyzed. All five fruits are excellent sources (32-138% DV) of vitamin C per 140 g (FDA serving, approximately 1 cup). Other standouts are mango for vitamin A and folate (45% and 21% DV, respectively); mamey sapote for potassium (21% DV); and cherimoya and mamey sapote for fiber (20% and 26% DV, respectively). Papaya has 2173 μg lycopene per 140 g. These new analytical values will enable researchers, clinicians, and consumers to more accurately assess the nutrient intakes of Latin Americans. INTRODUCTION The USDA National Nutrient Database for Standard Reference (SR) is an important source of nutrient composition data for foods consumed in the U.S. As the Latino population in the U.S. increases, there is a greater need to serve this population by adding nutrient data to SR for foods they commonly consume. Many people seek the fruits they consumed in their native countries, resulting in increased tropical fruit imports such as mangos and papayas (Pollack, 2001). The general population is able to enjoy more tropical fruits with the greater availability resulting from the increased demand. Four tropical nectars and 5 tropical fruits were analyzed in order to update SR with quality nutrient data for foods commonly consumed by Latinos. METHODS Tropical nectars and whole fruits were sampled and nutrient components analyzed using the following procedures: Nectar •National Food and Nutrient Analysis Program (NFNAP) – probabilitybased, nationwide retail sampling. •Obtained two brands of each of following types of nectar: guanabana (soursop), guava, mango, and tamarind. •Food Analysis Laboratory Control Center (FALCC) at Virginia Polytechnic Institute and State University prepared samples according to standard protocols and shipped composited samples to pre-qualified analytical laboratories along with quality control materials. Fruit •Types of fruit were selected based on recommendations by the Nutrition Coordinating Center, at University of Minnesota from results of the multicenter epidemiologic Hispanic Community Health Study. •NFNAP probability-based sampling method not feasible due to limited availability. •Ordered from U.S. wholesalers via Internet; arrived at various stages of ripeness and allowed to fully ripen before composited at FALCC. •Fruits studied and their scientific names and countries of origin (according to the wholesaler) were cherimoya, Annona cherimola, Chile and U.S. (CA); jackfruit, Artocarpus heterophyllus, U.S. (FL); mamey sapote, Pouteria sapota, U.S. (FL); mango, Mangifera indica, Mexico and U.S. (FL); and papaya, Carica papaya, Brazil, Mexico and U.S. (FL). Laboratories conducted analyses of proximate components, sugars, dietary fiber, vitamins, minerals and carotenoids in all of the nectars and fruit using AOAC or other published methods. CONCLUSION Nutrient composition information assists consumers in making more informed food choices to positively impact their health. All four nectars were added to USDA’s SR in earlier releases. The cherimoya was updated with the new data in the recently released SR22 (USDA, 2009). The remaining four tropical fruits will be updated in SR23. A few more types of tropical fruits commonly consumed by Latinos will be sampled and analyzed in the future. New data will aid in the assessment of nutrient intakes of Latin Americans and help health professionals provide dietary guidance to this population .

Heat resistance of the spoilage yeastsCandida pelliculosaandKloeckera apisand pasteurization values for some tropical fruit juices and nectars

Spoilage yeasts, identified asCandida pelliculosaandKloeckera apis, were isolated from fermented pasteurized pineapple juice, guava and passion fruit nectars, and studied for their heat resistance in relation to the pasteurization process of the beverages. The decimal reduction times (DT) obtained between 55 and 60°C forK. apisvaried from 1.41 to 2.49 min, and those forC. pelliculosaobtained between 60 and 75°C varied from 1.03 to 4.90 min depending upon the beverage and the tested temperatures.C. pelliculosaseemed to be more heat resistant thanK. apis. Thez-values or the increase in temperature needed to reduce theDTby 10, determined between 60 and 75°C forC. pelliculosa, were 31.75±0.03°C (r2=0.91) in pineapple juice, 27.70±0.04°C (r2=0.90) in passion fruit nectar and 34.84±0.02°C (r2=0.998) in guava nectar. ForK. apis, thez-values determined between 55 and 60°C were 21.88±0.07°C (r2=0.97) in pineapple juice, 22.73±0.04°C (r2=0.99) in guava nectar and 29.07±0.01°C (r2=0.999) in passion fruit nectar. The minimal pasteurizing valuesPTzwere determined forC. pelliculosaat 70°C and at 75°C, at a pasteurization efficiency (logN0/N) of 9. In pineapple juice,Pz70=27.91 min andPz75=13.5 min would have be applied to destroy almost any vegetative forms of the yeast. In passion fruit nectar,Pz70=20.25 min andPz75=9.27 min, and in guava nectarPz70=16.83 min would have be applied.

Modeling growth for predicting the contamination level of guava nectar by Candida pelliculosa under different conditions of pH and storage temperature.

The combined effects of temperature (2-46 degrees C) and pH (1.55-6.25) on the growth of Candida pelliculosa isolated from guava nectar produced in Cameroon were studied using a turbidity method, ie measurement of optical density at 630 nm. A quadratic polynomial model was constructed to predict the effects and interactions of these two environmental conditions on the maximal optical density obtained (i2 = 0.97). The relation between optical density and population density of C. pelliculosa (CFU ml-1) was also established using an exponential regression (2 = 0.99). According to the model, maximal growth conditions were 37 degrees C and pH 6.25 for obtaining the maximal optical density of 1.25 corresponding to about 60 x 10(6) CFU ml-1. A good agreement of the model was found between the predicted values and the observed values of maximal optical density. The model was validated by the experimental values of maximal optical density obtained in the growth of C. pelliculosa in commercial guava nectar (pH 3.15).

Production of clear guava nectar

SummaryThree fining methods were tested for use in producing clarified guava nectar. The enzyme hydrolysis method, especially treating the guava purée with 1000ppm of pectinase at 50°C for 3 h, accomplished satisfactory clarification but caused severe losses in volatile components, pre‐treating the purée with 100ppm of pectinase for 1 h greatly facilitated the subsequent bentonite or ultrafiltration clarification processes, and both the bentonite treatment and the ultrafiltration process yielded clarified product, but the ultrafiltered product had less loss of volatiles. However, to achieve storage stability, a membrane of lower than 100000 dalton molecular weight cut‐off should be used.

Howard Mold Count of Fruit Nectars, Purees, and Pastes: Collaborative Study

The various mold count methods for nectars, purees, and pastes make no adjustment for concentration of the pulped liquid. Thus, mold counts of different forms of the same product (e.g., guava nectar, puree, or paste) or of the same product from different manufacturers cannot be compared. A method was developed in which the product is centrifuged under standardized conditions, then diluted to a standard pellet-to-final-volume ratio. Because variations in the concentration of fruit or vegetable tissue are corrected, comparisons of mold counts are possible. The method was adopted official first action.

Studies on the Stability of Vitamin C at Elevated Concentrations in Canned Tropical Fruit Juices and Nectars

Studies were conducted to determine the stability of vitamin C at elevated concentrations in canned tropical fruit juices and nectars. Canned guava nectar, as well as juices of orange, tomato, and pineapple were fortified with ascorbic acid at seven different levels ranging from the original content present in the samples to about 300 mg. per 100 ml. Half of the samples were stored at room temperature and the other similar half at 100°F. for a period of 6 months. The results indicated that the losses of vitamin C were higher in the samples stored at 100°F. than in those stored at room temperature—regardless of the level of concentration. However, in the guava nectar the percentage of vitamin C destruction was relatively higher at lower concentrations and lower at higher concentrations at both temperatures. No such pattern could be observed in the juices. But the losses of vitamin C in the juices at all levels of concentration ranged below 30 percent at room temperature and below 40 percent at 100°F. This is relatively less than the losses that occurred in the guava nectar.

Título en español.

Se ha podido demostrar la presencia de la metilesterasa de pectina en la guayaba. Se sugiere que la demetoxilación parcial de la pectina presente en los néctares de guayaba y la subsiguiente formación de pectinatos de iones bivalentes pueden ser responsables de la presencia de los coágulos insolubles que se encuentran en algunos néctares de guayaba enlatados.