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Volume 13, Issue 2, 2024

Online ISSN: 2182-1054

Volume 13 , Issue 2, (2024)

Published: 18.10.2024.

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01.12.2013.

Professional paper

The relationship between antibrowning, anti-radical and reducing capacity of Brassica and Allium extracts

Aqueous vegetable extracts from Allium and Brassica families were assayed for antibrowning capacity and related to their anti-radical and reducing power activities. The treatment  of mushrooms and avocado slices, with white cabbage, cauliflower, garlic and scallion extracts, reduced color changes during storage at 4 °C and -18 °C. Storage temperature and the type of extract employed influenced change of color variables. The contribution of polyphenols on measured antioxidant activity of extracts was also discussed. Allium antibrowning properties were closely related to antioxidant capacity, while the Brassica extracts were less effective. Treatment with Allium extracts extended the storage time of frozen and refrigerated mushrooms and avocado slices, in comparison with untreated samples.

Mariela C Bustos, Lina Marcela Agudelo-Laverde, Florencia Mazzobre, Pilar Buera

01.12.2013.

Professional paper

Fermentation and antimicrobial characteristics of Lactobacillus plantarum and Candida tropicalis from Nigerian fermented maize (akamu)

This study investigated the ability of Lactobacillus plantarum strains (NGL5 and NGL7) and Candida tropicalis (NGY1) previously identified from akamu-a Nigerian fermented maize food with probiotic L. plantarum LpTx and Saccharomyces boulardii SB20 to ferment ground maize slurries based on pH, acidity, microbial biomass, levels of sugars and organic acids, and their antimicrobial activity against Salmonella enterica serovar Enteritidis NCTC 5188, Escherichia coli NCTC 11560, Bacillus cereus NCIMB 11925, Staphylococcus aureus NCTC 3750 and Listeria monocytogenes NCTC 7973 using an agar spot assay. L. plantarum strains either as single or mixed starter cultures with the yeasts had growth rates ≥0.15 h-1,with pH significantly (p≤0.05) decreased to ≤3.93 after 12 h and then to ≤3.52 after 72 h and lactic acid >84 mmol L-1. The yeasts had growth rates ≥0.18 h-1 but pH was ≥4.57 with lactic acid levels ≤20.23 mmol L-1 after 72 h in the single culture fermentation. There was no inhibition in modified MRS agar: 0.2% glucose and 0.2% glucose without Tween 80. Inhibition halos in MRS agar varied from 10.6 to 23.9 mm. S. bourladii was more inhibitory towards L. monocytogenes (8.6 mm) and B. cereus (5.4 mm ) than was C. tropicalis (1.1 and 3.3 mm for L. monocytogenes NCTC 7973 and B. cereus NCIMB 11925 respectively) (0.9 mm) in malt extract agar. This study showed that C. tropicalis was less inhibitory to the pathogens while antimicrobial activities of the L. plantarum strains were mainly due to acidity and the L. plantarum strains either as single or mixed cultures with the yeasts demonstrated strong fermentation ability, with significant decrease in pH which is vital in the choice of starter for product safety.

Patience Chisa Obinna-Echem, Victor Kuri, Jane Beal

01.12.2012.

Professional paper

Physical properties of honeys produced in the Northeast of Brazil

The aim of this work was to study the rheological, thermal and some other physical-chemical properties of selected honeys produced in the Northeast of Brazil. Two samples were produced by native “Jandaira” bees (Melipona subnitida) and ten other samples by Africanized bees (Apis mellifera). The samples were analyzed for pH, water activity (aW), soluble solids and water content. Viscosity flow curves were obtained using a rheometer (25ºC, 0-100s-1). Thermal analyses were performed on a differential scanning calorimeter, with heating rate of 10ºC/min (-100 to 100ºC). The water content and the pH of the honey samples varied from 17.2 to 27.9% and from 3.2 to 4.2, respectively, and, the aW of the samples varied from 0.57 to 0.74. Two samples were out of specification with respect to water content, according to Brazilian laws. In relation to rheology, all honey samples showed Newtonian behaviour with no thixotropy or dilatancy. The viscosity varied as an exponential function of the water content. The highest viscosity was obtained for the sample with lower values of water content and aW. Thermograms showed a glass transition (Tg) occurring between -52.4 and -42.6ºC, in the samples produced by Apis mellifera and -67.6 and -57.0ºC for the other samples. A linear relationship was obtained between Tg and water content. In conclusion, the honey viscosity depended on the water content of the product. The higher the water value and therefore the greater the aw, the lower viscosity and Tg of the samples.

Patricia Argemira Costa, Izabel Cristina Freitas Moraes, Ana Mônica Q.B. Bittante, Paulo José do Amaral Sobral, Catarina A. Gomide, Celso C. Carrer

01.12.2012.

Professional paper

Optimization of the Extraction of Antioxidants and Caffeine from Maté (Ilex paraguariensis) Leaves by Response Surface Methodology

Optimal conditions for the industrial extraction of total polyphenols from maté (Ilex paraguariensis) were determined using response surface methodology, with two independent variables: ethanol percentage of the extraction solution and liquid to solid ratio. Response variables were total polyphenol content, antioxidant capacity, concentration of total polyphenols and caffeine content. The optimal conditions found were a liquid to solid ratio from 8 - 9 w w-1 and ethanol percentage of the extraction solution from 30 -50 % w w-1. Under these conditions the main predicted values corresponding to leaf extracts were 40 μg chlorogenic acid equivalents mL-1 of original extract, 13 g chlorogenic acid equivalents per 100 g dry matter for total polyphenol content, 22 g Trolox equivalents and 15.5 g ascorbic acid equivalents per 100 g dry matter for antioxidant capacity. The total polyphenol content of twig extracts was 36% lower than that in the leaf extracts.

Vanessa Graciela Hartwig, Miguel Eduardo Schmalko, Stella Maris Alzamora, Luis Alberto Brumovsky

01.12.2012.

Professional paper

Effect of Biopreservatives on Storage Life of Papaya (Carica papaya L.)

In this experiment the effect on post-harvest preservation of papaya (Carica papaya L.) fruit coated with either Aloe gel (AG; 100%) or papaya leaf extract with Aloe gel (PLEAG; 1:1) was studied. To evaluate the role of coating on ripening behavior and quality of papaya the uncoated and coated fruits were stored and ripened at room temperature (25 °C-29 °C) and 82-84% relative humidity. Physico-chemical properties were analyzed at 4 day intervals during the storage period. The incidence of disease attack was also visually observed. The overall results showed the superiority of AG and PLEAG coating in lengthening the shelf-life of papaya fruit compared to controls which showed significant decay from 6th day onward and complete decay within 12 days of storage. The AG and PLEAG coated fruits maintained their shelf life for 12 days and decayed at 16th day. The coated fruits also maintained their color, flavor and firmness up to 12 days of storage. An increase in ascorbic acid content (120.2 mg/100 g) was also found in coated fruits in contrast to the control (59 mg/100 g). Only 27% disease incidence was observed in AG and 13% in PLEAG coated fruits as compared to control (100%) during the storage period. The results of this study show that both AG and PLEAG coatings have excellent potential to be used on fresh produce to maintain quality and extend shelf-life.

Fatema H. Brishti, Jawadul Misir, Ayesha Sarker

18.04.2012.

Professional paper

Effect of antioxidant and optimal antimicrobial mixtures of carvacrol, grape seed extract and chitosan on different spoilage microorganisms and their application as coatings on different food matrices

There is growing interest in the use of natural agents with antimicrobial (AM) and antioxidant (AOX) properties. Optimization of the AM capacity for mixtures containing carvacrol, grape seed extract (GSE) and chitosan, against gram-negative (Pseudomonas aeruginosa), gram-positive bacteria (Staphylococcus aureus, Listeria innocua and Enterococcus faecalis) and yeast (Saccharomyces cerevisiae) at 106 cfu mL-1 was studied. To observe the synergistic or antagonistic effect and find optimal combinations between the three agents, a simplex centroid mixture design was run for each microorganism, combining carvacrol (0-300 ppm, X1), GSE (0-2000 ppm, X2) and chitosan (0-2% w/v, X3). Results of the response surface analysis showed several synergistic effects for all microorganisms. Combinations of 60 ppm-400 ppm-1.2% w/v (carvacrol-GSE-chitosan; optimal AM combination 1, OAMC-1); 9.6 ppm-684 ppm-1.25% w/v (OAMC-2); 90 ppm-160 ppm-1.24% w/v (OAMC-3) were found to be the optimal mixtures for all microorganisms. Radical scavenging activity (RSA) of the same agents was then compared with a standard AOX (butylated hydroxytoluene; BHT) at different concentrations (25, 50 and 100 ppm; as well as the optimal AM concentrations) by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. RSA increased in the following order: chitosan< carvacrol< BHT< GSE and for the OAMC: OAMC-2< OAMC-1< OAMC-3. The best RSA (OAMC-3) was applied as a coating in two different food matrices (strawberries and salmon). For strawberries, P. aeruginosa was more sensitive to the action of OAMC-3 than S. cerevisiae. For salmon, S. aureus was more resistant to the action of OAMC-3 than E. faecalis and L. innocua.

Javiera F. Rubilar, Rui M.S. Cruz, Igor Khmelinskii, Margarida Cortez Vieira

01.12.2012.

Professional paper

Effect of drying techniques on the retention of antioxidant activities of Saskatoon berries

The main objective of this research was to compare the retention of antioxidant activity and total anthocyanin content of Saskatoon berries dried by freeze drying, microwave-vacuum drying, thin layer hot air drying and vacuum drying. Antioxidant activity of berry samples was determined by DPPH radical scavenging and ABTS radical scavenging, and the pH differential method was used to determine total anthocyanin content of the berry samples. The results showed that the freeze dried Saskatoon berries exhibited the highest retention of anthocyanin and antioxidant activity among the dried samples, followed by microwave-vacuum dried berries, thin layer hot air dried berries and vacuum dried berries. There were significant differences between the berry samples at P<0.05.  DPPH radical scavenging and ABTS radical scavenging were correlated linearly with an R2 value of 0.99 at P<0.05 showing their effectiveness for the determination of the antioxidant activity of the Saskatoon berries. However, the DPPH radical scavenging assay was more effective than the ABTS radical scavenging assay. The results also showed that antioxidant activity of the berries was highly correlated with the total anthocyanin content of the fruit. The reduction of anthocyanin in dried berry samples was linearly correlated with the reduction of DPPH radical scavenging with an R2 value of 0.97 at P<0.05 and, also, linearly correlated with the reduction of ABTS radical scavenging with an R2 value of 0.88 at P<0.05.

Pranabendu Mitra, Venkatesh Meda, Rick Green

01.12.2012.

Professional paper

Effect of structural modifications on the drying kinetics of foods: changes in volume, surface area and product shape

Macro and micro-structural changes take place during food dehydration. Macro-structural changes encompass modifications in shape, area and volume. Studies of such changes are important because dehydration kinetics (essential for calculating industrial dryers) may be highly influenced by changes in food shape and dimensions. The overall changes in volume, surface area (“shrinkage”) and shape (Heywood factor, with provides a close description of food shape) were determined experimentally, and the results were correlated with simple expressions. Hence, although dehydration kinetics can be modeled with simplified overall shrinkage expressions, the possibility of selecting a suitable geometry and predicting the characteristics dimensions will provide higher accuracy. An additional unresolved problem is the lack of a general model that predicts macro-structural changes for various foods and diverse geometries. In this work, based on experimental data of sweet and sour cherries, and rose hip fruits, a simplified general model to predict changes in volume and surface area are proposed. To estimate how the changes in characteristic dimensions affect the kinetic studies, experimental drying curves for the three fruits by means of a diffusional model considered the following variants for the characteristic dimensions: (i) The radius of the fresh food, assumed constant; (ii) The radius of the partially dehydrated product; (iii) The radius predicted by the correlation for structural changes, especially volume, obtained in this work and generalized for the three fruits, and (iv) to demonstrate the need to study the macro-structural changes for all dehydrated foods, also be present the case of a restructured food.

Antonio De Michelis, Carlos A. Márquez, Alejandra Mabellini, Elizabeth Ohaco, Sergio A. Giner

01.12.2012.

Professional paper

Effects of modified atmosphere, associated with masterpack transport packaging, and refrigerated storage time on the quality characteristics of pork loin cuts

The objective of this research was to study the effects of modified atmosphere, associated with masterpack transport packaging, and refrigerated storage time on the quality characteristics of pork loin cuts. Cuts of pork loin were packaged in trays, covered with poly(vinyl chloride) film. The trays were placed in a masterpack (MP), containing three gas compositions:  A) 75% O2 : 25% CO2, B) 50% O2 : 50% CO2 or C) 100% CO2, and stored at 2 °C. Samples were taken after 1, 8, 15, and 22 days of storage, and evaluated for numerous shelf life traits. The development of Psychrotrophic aerobic bacteria and Pseudomonas spp. was found from the 15th day of storage. There was a significant treatment effect for some of the considered parameters, such as pH (P < 0.05) and color [L* (P < 0.07), a* (P < 0.07) and b* (P < 0.01)]. There was a significant interaction (P < 0.01) for the TBARS values. It can be concluded, from the microbiological point of view, that the use of modified atmospheres containing 25% to 100% CO2 promotes the conservation of meat for up to 15 days of storage under refrigeration. From the point of view of color, atmospheres containing 75% O2 : 25% CO2 and 50% O2 : 50% CO2 ensure the color of packaged pork meat when stored at 2 °C for up to 15 days. From the point of view of lipid oxidation, packages with 100% CO2 are recommended for storage periods of more than 15 days, whereas those with 75% O2 : 25% CO2 are recommended for storage periods of up to 8 days.

Alessandra F. Rosa, Mirele D. Poleti, Julio C.C. Balieiro, Marcelo C. César, Paulo J.A. Sobral

01.12.2012.

Professional paper

Physicochemical characterization of Gozitan Honey

Honey quality is clearly defined in the EU Directive 2001/110/EC, and by Codex Alimentarius (Codex Stan 12-1981) and the International Honey Commission (IHC, 2002). Our investigation aimed to characterize the physicochemical properties of honey produced on a small island, Gozo which is situated near Malta.  Ten randomly collected honey samples were analysed for moisture content, pH, free acidity, water insoluble content, hydroxymethylfurfural (HMF) content and total phenolic compounds.  Moisture content, pH, free acidity, water insoluble content, and HMF content were within the range specified in standards but the electrical conductivity was generally higher than 0.800 mS cm-1. This may be the result of the relatively high atmospheric and soil salinity on this small island. All the samples analysed were within the 40 mg kg-1 HMF limit, which is an indicator of honey quality. The total phenolic compounds, which represent some of the constituents derived from the nectar and pollen obtained during foraging, ranged between 236.555 and 294.209 GAE kg-1 honey. Principal Component Analysis showed the properties of polyfloral honey samples obtained from the southern part of the island to be different from those obtained from the northern part.

Everaldo Attard, Joseph Mizzi

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