Advances in Food Science and Engineering

5

Authors: Ayuba L., Agboire S., Gana A.K., Ishaq M., Aliyu U., Affiniki G., Manjang J. I.

The potential of using castor oil as an antibacterial agent was investigated on three species of bacteria chiefly responsible for throat, skin and enteric infections. Staphylococcus aureus was used as the test organism for skin bacteria, the throat bacteria used was Streptococcus viridans, while for enteric bacteria, Shigella dysenteriae was used. Castor oil was extracted by cold pressing of seed kernels. The extract obtained was assayed for antimicrobial activity on the in-vitro growth of test organism using direct inoculation, paper disc method. These were soaked in the castor oil for 1 hour. The soaked discs were then placed on prepared plates each containing the test bacteria, the antimicrobial effect of the castor oil was observed by measuring the zone of inhibition of the agent against the test bacteria. The result showed that castor oil is highly effective against all the bacteria species tested; the zone of inhibition measured, showed that Staphylococcus aureus is more susceptible to the oil than the other bacteria with a range of 11-13mm while Streptococcus viridans had a range of 8-10mm and the least was Shigella dysenteriae which had a range of 3-6mm. The result obtained implies that castor oil can be used in the control of wounds, skin infections, throat infections and in the treatment of stomach unrest caused by these bacteria species.

6

Authors: Samira Nair, Nebia Bouzidi Maghraoui

Honey is a nutritious product that is produced by honey bees. Its composition depends highly on the type of flowers utilised by the bee as well as the climatic conditions. This study was intended to evaluate the quality parameters of ten honey samples, from various regions in NorthWest of Algeria. The physicochemical property of the honeys [moisture, electrical conductivity, hydroxymethylfurfural, pH, acidity (free, total and lactone), reducing sugars, apparent sucrose, insoluble material, ash, and diastase activity] was determined. The moisture shows values of 14.21±0.18 % and 16.59±0.12%. The water insoluble material content ranged between 0.01 ± 0.03 to 0.67 ± 0.07%. The reducing sugars were between 66.3 ± 0.37 and 88 ± 0.23 %, mean percentages of apparent sucrose were 6.54 ± 0.23%. Honey samples showed an appropriate diastase number with an average of 12.35 ± 0.24, and their HMF (hydroxymethylfurfural) content ranging from 5.65 ±0.37 to 37.42 ± 0.55 mg/kg, Conductivity values ranged from 10 ± 0.54 to 606 ± 2.45 µS/cm. The ash content ranged from 0.019 ± 0.01% to 0.37 ± 0.05%. All honeys were acidic, having a pH in the range 3.7 ± 0.03– 4.78 ± 0.05. The average values for free acidity in samples were between 10 ± 0.22 and 25 ± 0.5 meq/kg. Lactonic acidity ranges were from 2 ± 0.15 to 5 ± 0.15 meq/kg. Total acidity ranged from 12 ± 0.37 to 30 ± 0.65 meq/kg. All the samples were found to meet all major national and international honey specifications.

11

Authors: Fernanda Rosa Assis, Rui Manuel Santos Costa de Morais, Alcina Maria Miranda Bernardo de Morais

The aim of the present work was to study the effects of the osmotic dehydration (OD) on the mass transfer kinetics of the microwave drying (MWD) and some quality parameters of apple cubes. The fit of several mathematical models was tested to describe the drying. A comparison between MWD and hot air drying (HAD) was performed. Apple cubes were osmotically treated with 60ºBrix sucrose or sorbitol solutions at 60ºC and dried at a microwave power between 160 and 850 W. Overall, the increase of the microwave power from 160 to 500 W resulted in an increase of the water loss rate, shown by the A parameter of modified Page’s model, of 123 and 155% for samples osmotically dehydrated with sucrose and sorbitol solutions, respectively. The OD tends to increase the drying rate, but the osmotic agent used did not have any effect. The modified Page's model described well the drying kinetics and MWD was faster than HAD. The water activity of the osmotically dehydrated product was reduced to below 0.4 after MWD at 500 W. The MWD of control samples resulted in a loss of 39% and 28% of the total phenolic content and the antioxidant activity, respectively. For osmotically dehydrated samples, a loss of around 75% was observed for both these quality parameters after the osmotic treatment.

6

Authors: V.M. Bhatt, M.N. Dabhi, P.J. Rathod

Experiments were conducted to assess a storage of bajra flour of five cultivars viz GHB- 538, GHB-558, GHB-732, GHB-744, Desi(V) with different packaging materials of Tin container(C1), HDPE container(C2), Cotton bag(C3), LDPE bag(C4) at room temperature(T1:37°C) and at low temperature (T2:refrigerator) for 16 days. The best storage condition to enhance the keeping quality of flour of Bajra varieties with effect of storage containers and temperature on biochemical quality parameters of Bajra flour was analyzed. The increase in moisture content (1.85 %) was higher in Desi Variety flour at room temperature in cotton bag. The increase in FFA (3.35%) was higher in GHB- 558 variety flour at room temperature in cotton bag. The increase in Malondialdehyde was higher in GHB-538 as well as GHB-558 flour stored in cotton bag at room temperature. The increased values of all parameters were found in flour stored in tin container and plastic container at low temperature.

9

Authors: Pablo Otero-Pazos, David Antonio Pereira de Abreu, Raquel Sendon, Ana Rodríguez Bernaldo de Quirós, Inmaculada Angulo, Jose Manuel Cruz, Perfecto Paseiro

Polymeric materials have been extensively used in food packaging. The main problem associated to plastics is the migration of low molecular substances from the material to the food, which may be potentially dangerous for the consumers’ health. The key parameters of the migration are the partition and diffusion coefficients. The development of polymer nanocomposites is expected to provide new materials with enhanced properties and safer food packaging. This work describes a procedure to determine the partition coefficients of selected model substances between low-density polyethylene (LDPE) and polyamide (PA) and, between LDPE and nanocomposite polyamide (naPA). The assays were conducted at different time-temperature conditions. The model migrants were extracted from the polymeric materials with ethanol and analyzed by RP-HPLC-DAD-FLD. The values of the partition coefficients obtained ranged from 0.01 to >1000. The results obtained suggest that the incorporation of nanocomposites could affect the solubility of certain compounds into the polymeric matrix.

8

Authors: Slim Blidi, Panagiota Gotsiou, Sofia Loupassaki, Spyros Grigorakis, Antony C. Calokerinos

The aim of the current study was to investigate the effect of the main thermal treatments used in practice by beekeepers and packagers on hydroxymethylfurfural content and diastase activity of Cretan honey. Results showed a significant alteration of both quality parameters under heating at 65 °C for 6 h (P<0.05) while heating at 45 °C for 24 h was found to be the least severe treatment with regards to the variation of the two quality parameters (P<0.05). After heating, a significant differentiation was also observed in the variation of both HMF content and diastase activity according to the botanical origin of the honey sample (P<0.05). Pine honey was the most resistant sample in hydroxymethylfurfural formation in all heating procedures and multifloral honey was the least altered in its enzymatic activity through the whole thermal process.

10

Authors: Ramón Moreira, Francisco Chenlo, María D. Torres, Diego M. Prieto

Experimental water desorption isotherms of glucose, fructose and sucrose were determined at different temperatures (20, 35, 50, and 65ºC) using a static gravimetric method. Saturated salt solutions were selected to obtain different water activities from 0.09 to 0.91. All tested isotherms were type III following Brunauer’s classification. The experimental data were satisfactory fitted by Henderson and Iglesias and Chirife models. A complete statistical analysis was performed, determining that Henderson model was more suitable to fit the desorption isotherms of tested sugars, since it satisfied all the rejection criteria and showed, in all studied cases, the highest values of lumped measure for the goodness of fit. Predicted water desorption isotherms of sucrose from the experimental sorption isotherms of its individual monomers (glucose and fructose), in moles of water per mol oxygen, nicely matched with those obtained experimentally.

19

Authors: Khadiga A. A. Abou-Taleb, Wedad E. Eweda, H. I. Mira

The heavy metal resistant isolate FR1 was identified using phenotypic and genotypic characteristics; it was classified as Aspergillus terreus strain. Lactose and yeast extract were favorable for Cr+5 and Cu+2 ions biosorption by tested strain after 6 days incubation period. The positive significant variables (yeast extract, temperature & inoculum size or lactose, yeast extract, temperature & incubation period) affecting heavy metals biosorption using Placket-Burman statistical experimental design in presence Cr+5 and Cu+2 were further optimized by using response surface methodology. It was found that the highest growth of strain in presence of Cr+5 and Cu+2 (4.31 and 3.69 gL-1) were attained at 0.15% yeast extract, 2% inoculum size & incubated at 28°C and 0.65 % lactose, 0.15% yeast extract, an incubation temperature of 30 °C and 8 days incubation period, respectively. There is no significant difference between absorption and adsorption mechanism for reduction of heavy metals from Egyptian phosphatic fertilizer sample.