Color of berry and juice of 'Isabel' grape treated with abscisic acid in different ripening stages

Abstract : The objective of this work was to evaluate the effect of (S)-cis-abscisic acid (S-ABA) application at different ripening stages, in increasing phenolic compounds and color of berry and juice of 'Isabel' grape (Vitis labrusca). The evaluated treatments were: control, without S-ABA application; 400 mg L-1S-ABA applied 7 days before veraison (DBV) + 400 mg L-1S-ABA at 35 days after first application (DAFA); 400 mg L-1S-ABA applied at veraison (V) + 400 mg L-1S-ABA at 35 DAFA; and 400 mg L-1S-ABA applied 7 days after veraison (DAV) + 400 mg L-1S-ABA at 35 DAFA. There was no difference among treatments regarding the physical characteristics of berries and clusters, as well as total polyphenols in berry and juice. However, there was an increase in total anthocyanins in berry and juice with S-ABA application. Colorimetric variables indicated the increase in color of berry treated with S-ABA. Juices produced from grapes treated with S-ABA were more appreciated by tasters. The treatments with 400 mg L-1S-ABA applied 7 days before, during, or 7 days after veraison, combined with an additional application 35 days after the first one, increment total anthocyanin concentration and color of berry and juice of 'Isabel' grape, with better juice acceptance, without affecting total polyphenol concentration.

Papaya pulp gelling: is it premature ripening or problems of water accumulation in the apoplast?

Gelled aspect in papaya fruit is typically confused with premature ripening. This research reports the characterization of this physiological disorder in the pulp of papaya fruit by measuring electrolyte leakage, Pi content, lipid peroxidation, pulp firmness, mineral contents (Ca, Mg and K - in pulp and seed tissues), and histological analysis of pulp tissue. The results showed that the gelled aspect of the papaya fruit pulp is not associated with tissue premature ripening. Data indicate a reduction of the vacuole water intake as the principal cause of the loss of cellular turgor; while the waterlogged aspect of the tissue may be due to water accumulation in the apoplast.

Effects of modified atmosphere packaging on ripening of 'Douradão' peach related to pectolytic enzymes activities and chilling injury symptoms

The present study evaluated the effects of modified atmosphere packaging on inhibition of the development of chilling injury symptoms in 'Douradão' peach after cold storage and the possible involvement of cell wall enzymes. Fruits were harvested at the middle stadium of ripening, packed in polypropylene trays and placed inside low density polyethylene (LDPE) bags (30, 50, 60 and 75 µm of thickness) with active modified atmosphere (10 kPa CO2 + 1.5 kPa O2, balance N2). The following treatments were tested: Control: peaches held in nonwrapped trays; MA30: LDPE film - 30 µm; MA50: LDPE film - 50 µm; MA60: LDPE film - 60 µm and MA75: LDPE film - 75 µm. Fruits were kept at 1±1ºC and 90±5% relative humidity (RH) for 28 days. After 14, 21 and 28 days, samples were withdrawn from MAP and kept in air at 25±1ºC and 90±5% RH for ripening. On the day of removal and after 4 days, peaches were evaluated for woolliness incidence, pectolytic enzymes activities. The respiratory rate and ethylene synthesis were monitored during 6 days of ripening. The results showed that MA50 and MA60 treatments had positive effect on the inhibition of the development of woolly texture and reduced pectin methylesterase activity on the ripe fruits, keeping good quality of 'Douradão' peach during 28 days of cold storage. The treatments Control, MA30 and MA75 showed higher woolliness incidence and did not present marketable conditions after 14 days of cold storage.

Ostwald ripening in porous materials

The process of coarsening of an ensemble of clusters is investigated for the case that elastic strains due to matrix - cluster interactions change the process qualitatively as compared with dependencies established theoretically first by Lifshitz and Slezov. Such a qualitatively different behavior occurs always when the energy of elastic deformation in cluster growth increases more rapidly than linear with the volume of a cluster. Analytic solutions, for limiting cases, as well as numerical solutions, for the general case of coarsening in an ensemble of pores with a given pore size distribution, are presented. Possible applications are discussed.

Isolation of microorganisms of cheese whey with lipolytic activity for removal of COD

The aim of this study was to isolate microorganisms that produce lipase and to assess the efficiency of COD removal intreatment of cheese whey under different operating conditions. The microorganisms were isolated from cheese whey and a commercial product; it was selectedthreemicroorganisms that obtained the best response to the lipolytic activity test through the enzyme index. Then, the microorganisms were inoculated in sterilized cheese whey samples, for two pH values (6.2 and 7.0), incubated at 35 °C and 150 rpm in shaker and the lipolityc activity and the efficiency of COD removal were measured in two time periods (24 and 48h). After incubation, it was observed that the treatments showed a good removal efficiency of COD for the pre-treatment and the isolated microorganism (S1) from the cheese whey showed the highest lipase production. Regarding the pH and time variables, there was not significant effect between the two evaluated factors. Among all treatments, T2 (S1, pH 7.0 and 24h) obtained more enzyme production (4.87 U mL-1).

Aflatoxin M1 in samples of "minas" cheese commercialized in the city of Belo Horizonte - Minas Gerais/Brazil

Milk products such as cheeses may be contaminated by aflatoxin M1 when dairy cattle have consumed feeds contaminated with aflatoxin B1. Samples of "Minas" cheeses (fresh, canastra and standard) were collected by the Inspection Service in the Mercado Central in Belo Horizonte city, Minas Gerais - Brazil. A purified extract was obtained by extraction with dichloromethane followed by a washing with n-hexane and immunoaffinity column purification. The quantification of aflatoxin M1 was done by high performance liquid chromatography (HPLC) using a fluorescence detector. Recoveries were about 75%. In 56 of the 75 samples (74.7%), the presence of aflatoxin M1 was detected in concentrations ranging between 0.02 and 6.92ng/g of cheese. In the positive cases ( > or = 0.02ng/g) the mean contamination level of aflatoxin M1 was 0.08ng/g in fresh cheese, 0.36ng/g in canastra cheese and 0.62ng/g in standard cheese. No aflatoxin M1 maximum tolerance level in cheese has been established in Brazil.

Volatile compounds in noni (Morinda citrifolia L.) at two ripening stages

The volatile components of noni at two ripening stages were isolated by headspace solid-phase microextraction using 65 µm Polydimethylsiloxane-Divinylbenzene (PDMS/DVB) fibers and analyzed using GC/MS. Both maturation stages had several compounds in common. Ninety-six compounds were identified, from which octanoic acid ( 70% of total extract) and hexanoic acid ( 8% of total extract) were found to be the major constituents. Due to noni maturation, octanoic acid, decanoic acid and 2E-nonenal decreased their concentrations, while some esters (methyl hexanoate, methyl octanoate, ethyl octanoate and methyl 4E-decenoate), which their fruity odor notes, increased their contents. Two unsaturated esters, reported for the first time in this fruit, 3-methyl-3-buten-1-yl hexanoate and 3-methyl-3-buten-1-yl octanoate, significantly decreased their concentration in the ripe to over-ripe fruits.

Inhibitory effect of the essential oil from Eugenia caryophyllata Thumb leaves on coalho cheese contaminating microorganisms

Coalho cheese (a firm but very lightweight cheese produced in Brazil) is widely produced and consumed in the Brazilian Northeast and its production has been mainly related to small farmers. This food has been frequently characterized as having high microbial load posing a risk for the health of consumers. This study aimed to indentify the chemical compounds of the essential oil from Eugenia caryophyllata leaves; to evaluate the inhibitory effect of the oil against coalho cheese contaminating microorganisms; and to assess its efficacy in inhibiting the autochthonous microflora of the cheese during refrigerated storage. Eugenol (74%) was found to be the most prevalent compound in the essential oil. Minimum Inhibitory Concentration (MIC) and Minimum Cidal Concentration (MCC) in laboratorial broth were in the range of 2.5-5 and 5-20 µg.mL-1, respectively. Vaccum packed coalho cheese added with 5, 10, and 20 µg.g-1 of oil showed a lower growth rate (like-static effect) against mesophilic bacteria during the time intervals evaluated. On the other hand, 2.5-10 µg.g-1 of oil provided a prominent decrease toward fungi count in cheese samples during storage. These results reveal the interesting antimicrobial property of the essential oil from E. caryophyllata leaves against a range of coalho cheese-related microorganisms in laboratorial media and in food matrix.

Analysis of virulence genes in Escherichia coli isolated from grated cheese

This research aimed to verify the presence of virulence genes in strains of Escherichia coli isolated from grated cheese sold in farmers' markets of Cuiabá-MT, Brazil. Forty samples of this food were submitted for microbiological analysis and 22 (55%) tested positive for E. coli. Next, 64 strains of E. coli were isolated from the positive samples and screened by the polymerase chain reaction (PCR) for the presence of the genes encoding the following virulence factors: stx1 and stx2 (verotoxin types 1 and 2), eae (intimin), lt1 (heat-labile toxin type 1), st1 (heat-stable toxin type 1), cnf1 and cnf2 (cytotoxic necrozing factor types 1 and 2), and cdtB (cytolethal distending toxin). All the isolates were negative for the genes stx1, stx2, eae, lt1, st1, cnf1, and cdtB, and five strains (7.81%) were positive for cnf2. A low prevalence of E. coli positive for virulence factors associated with the pathogenesis of diarrhoea was observed in this study. However, the presence of CNF-2 producing strains and the possibility of occurrence and scattering of other virulence factors that were not surveyed in the work indicate the risk related to the consumption of grated cheese from farmers' markets.

Partial purification and characterization of a bacteriocin produced by Enterococcus faecium 130 isolated from mozzarella cheese

Lactic acid bacteria are important in foods as potential probiotics and also due to the ability to produce antimicrobial compounds that can contribute for biopreservation. In this work, the bacteriocin produced by the food isolate Enterococcus faecium 130 was partially purified and characterized. The compound was active against Gram-positive bacteria, including Listeria monocytogenes. It was produced after 4 days of storage at a broad temperature range (4 to 37 °C); it was stable at pH ranging from 2 to 10 with no loss of activity after heating at 100 °C for 15 minutes. Bacteriocin was partially purified by the adsorption-desorption technique, and the analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed a molecular mass of 3.5 to 6.5 kDa. These data encourage studies on application of this bacteriocin in food systems as an additional hurdle to microbial growth.

Sugar fractionation and pectin content during the ripening of guava cv. Pedro Sato

Guava is one of the most complete and balanced fruits in in terms of s nutritional value. Highly perishable, due to its intense metabolism during ripening, its shelf life can reach 3 to 5 days under room temperature. The firmness of the green and mature fruits is due mainly to the pectin polymers. The loss of firmness during the guava ripening is due to hydrolytic enzyme activity, which promotes intense solubilization of the cell wall pectins. Given the above, with the purpose of trying to explain the rapid firmness decrease, the centesimal composition and sugar fraction of the guava fruit were determined during ripening at room temperature. The guavas were picked at the half-mature stage and stored for 8 days at 22 ± 1 ºC and 78 ± 1% relative humidity. The analyses conducted were: centesimal composition, sugar fractionation, and infrared absorption spectrometry. The results showed that the guava sugars did not vary during ripening. The estimated pectin levels (5.7%) were higher than those mentioned in the literature (2.4%), which can better explain the role of the pectin in the fruit firmness.

Histochemistry and morphoanatomy study on guava fruit during ripening

Guava (Psidium guajava L.) is a highly perishable fruit due to its intense metabolism during ripening. Information on the enzyme activities that degrade pectic substances, as well as the amount of pectin, is very contradictory and not clearly defined. Thus, this study aimed to monitor the changes occurred in the fruit during ripening through histochemical, physical, and scanning microscopy processes. Guavas were picked at the half-mature stage and stored for 9 days at 22 ± 1 °C and 78 ± 1% RH. The analyses conducted on the day of harvest (0) and each day of storage (1, 2, 3, 4, 5, 6, 7, and 8 days) were: firmness and histochemical analyses (ferric chloride, lugol, comassie blue, vanillin hydrochloric, and ruthenium red) observed under an optic microscope and a scanning electron microscope. Ruthenium red showed a high amount of pectin in the cell wall on day zero as well as its decrease in the wall during ripening and its accumulation in the central area of the cell. Scanning microscopy showed loss of the cell structure during ripening. Those observations suggest that the pectin is the main polymer responsible for firmness maintenance in the guava fruit.

Physicochemical changes in cubiu fruits (Solanum sessiliflorum Dunal) at different ripening stages

Cubiu shrubs (Solanum sessiliflorum Dunal) have drawn the attention of researchers for their biological versatility (preferential heliophilous or facultative ombrophilous shrubs), their capacity to grow in upland or lowland areas, and the good technological quality of their fruits for the food industry. The aim of this study was to verify physicochemical changes in cubiu fruits during maturation. The fruits were harvested from the experimental station of olericulture of the Instituto Nacional de Pesquisas da Amazônia (INPA), Brazil. The analyses were performed in whole cubiu fruits (peel, pulp, and placenta) at four traditional ripening stages (green, turning, ripe, and fully ripe) for the determination of weight, moisture, total solids, total carotenoids, proteins, lipids, and ash. Cubiu fruits showed large weight variation, with amodal distribution. The ripe stage was critical to maintain moisture, and from that stage on, water loss became evident. The lipids increased steadily over the four ripening stages, maintaining, however, insignificant calorie content. Total carotenoids, proteins, and ash reached the maximum level at the fully ripe stage. With the exception of weight and moisture, all physicochemical changes exhibited the same general behavior, i.e. they increased as the fruits ripened at the four investigated stages.

Ripening pattern of guava cv. Pedro Sato

Guava is a fruit with high respiration rates and a very short shelf life. Since information on its respiration pattern is contradictory, the objective was to study the changes occurring in the fruit during ripening and to relate them to the respiration behavior of this fruit. Guavas were picked at the half-ripe stage and stored for 8 days at 22 ± 1 ºC and 78 ± 1% relative humidity. The analyses conducted were: peel and pulp coloration, firmness, total soluble solids (TSS), total titratable acidity (TTA), and ethylene production. According to the results, it was verified that the parameters analyzed apparently do not coincide and are ethylene-independent. There was an accentuated ethylene production during ripening, starting from the 4th day. The ethylene synthesis continued increasing up to the 8th day, when the fruits were already decomposing. It was observed that the firmness decreased sharply in the first three days of ripening, and the skin and pulp color changed during ripening. The TSS, total soluble solids, and the TTA, total titratable acidity, practically did not change during the ripening, even with the increased ethylene production. It can be concluded that guava is a fruit that presents characteristics of climacteric and non-climacteric fruits.

Effect of incorporation of amaranth on the physical properties and nutritional value of cheese bread

At the present celiac disease has no known cure, and its only treatment is a strict lifelong adherence to a gluten-free diet. Cheese bread is a traditional Brazilian product and a safe option for celiacs. However, like other gluten-free breads, it has inherent low levels of fibers and minerals. The objective of this study was to evaluate the effect of incorporation of whole amaranth flour on the physical properties and nutritional value of cheese bread. Amaranth flour was incorporated at 10, 15, and 20% proportions in different formulations. The increasing amaranth levels darkened the product, reduced specific volume, and increased compression force. Ten percent amaranth-content cheese breads exhibited slight differences in physical properties compared with the controls. These results demonstrated the possibility of incorporating 10% of whole amaranth flour in the formulation of cheese bread resulting in a product with higher dietary fiber and iron contents and the same level of acceptance as that of the conventional formulation. The aim of this approach is to increase the availability of gluten-free bakery products with added nutritional value contributing to increase the variety of the diet of celiac patients.