JOURNAL OF FOOD BIOSCIENCES AND TECHNOLOGY
Year:2011 | Volume:1 | Issue:1|Papers Count:8

Nowadays, consumption of whole flours and flours with high extraction rate is recommended, because of their large amount of fiber, vitamins and minerals. Despite nutritional benefits of whole flours, concentration of some undesirable components such as phytic acid is higher than white flour. In this study, the effect of several sourdough lactic acid bacteria on toast bread was investigated. Sourdough was made from lactic acid bacteria (Lb. plantarum, Lb. reuteri) with different dough yields (Dy) and incubated at 30oC for 20 hours, then added to dough in the ratios of 10, 20 and 30% replacement. Breads supplemented with Lb. plantarum sourdough had lower phytic acid. Higher replacement of sourdough and higher DY caused higher decrease in phytic acid content. Sourdough made from Lb. plantarum, DY=300 and 30% replacement caused the highest decrease in phytic acid content (49.63 mg/100g). As indicated by the panelists, Lb. reuteri sourdough can present the greatest effect on overall quality score of the breads. DY reduction caused a decrease in bread quality score.Sensory score of toast bread was 81.71 in the samples treated with Lb. reuteri sourdough with DY=250 and 20% replacement.

Kefir is fermented milk that has a unique flavor because of acetaldehyde, diacetyl, acetoin and ethanol. The aim of this study was to evaluate flavor and aroma compounds present in kefir. Two types of starter (Christian Hansen and Sacco) and three levels of temperatures (30, 33 and 35oC) were used for the preparation of kefir samples. The samples were analyzed for acetaldehyde, diacetyl, acetoin and ethanol by GC equipped with FID detector. Levels of acetaldehyde, diacetyl, acetoin and ethanol were increased with raising the temperature and decreased during cold storage from the first day until the 14th day. pH was decreased and acidity was increased in all samples during cold storage. After organoleptic evaluation, the prepared sample by Sacco at 35oC was known as the best sample and then the prepared samples by Sacco at 33 and 30oC were recognized as the favorable samples.

Chemical composition of Lavandula angustifolia was studied by solvent free microwave extraction (SFME) and hydrodistillation (HD) methods.1, 8-cineole (42.7% and 37.9%), Camphor (26.1% and 21.3%) and Borneol (31.2% and 21.6%) were the major compounds that obtained by SFME and hydrodistillation, respectively. The antibacterial activity of extracted oils was investigated against Gram-positive bacteria Bacillus subtilis (B-sub) ATCC 6633 and Gram-negative bacteria Escherichia coli (E-coli) ATCC 8739.The minimum inhibitory concentration (MIC) of the essential oils isolated by hydrodistillation and SFME was the same.

The crystallinity of wheat starch in two types of flat breads was studied using Differential Scanning Calorimetery. Three types of flours with different proteins of 9.4, 11.6 and 13.5% were prepared and two different types of flat breads with thicknesses of 2 and 3 millimeters were baked from each flour. The crystallization enthalpy (DH), peak temperature (Tp) and onset point temperatures (To) of the DSC thermo grams were analyzed on the first and 3rd days of storage in all types of breads. Comparison of the results showed that the baking process and time influenced on the extent of starch crystallinity. In spite of the breads with 3mm thickness, the loss of crispiness in breads with 2 mm thickness proceeded over shorter times. In very thin flat breads (thickness of 2 mm), a temperature of about 100 C was rapidly riched, but due to the short time of baking process, starch was not fully gelatinized and the latter caused slower retrogradation upon the storage. The results indicated lower starch recrystallization enthalpy. Under the experimental conditions, high protein breads showed lower extent of retrogradation.

Vacuum deep-fat frying is a new technology that can be used to improve the quality attributes of fried food because of the low temperatures employed and minimal exposure to oxygen. In this paper the effect of frying process parameters, namely frying time, frying temperature and pressure on the quality factors of fried kiwi slices was studied. A laboratory scale vacuum frying apparatus was used to study the interactions and optimization of process parameters on the vacuum frying of kiwi fruit. Considering the results of pretests, the variables ranges were assumed as 80-120 oC for the temperature, 40-150 mbar for the vacuum pressure and 5-20 minutes for the processing time. The results indicated that the color and the shrinkage were significantly (p<0.05) correlated with the frying temperature and time, while the crispiness was affected only by the frying temperature. There was no significant relation between the vacuum pressure and the responses except the shrinkage. The results of sensory evaluation indicated that there were no significant differences (p<0.05) between the vacuum fried kiwi slices and the dried kiwi chips except flavor. The optimum conditions for the vacuum frying of kiwi slices were found to be: 105 oC, 62 mbar, and 8 min, for the frying temperature, the vacuum pressure and the frying time, respectively.

A combined gas chromatography-mass spectrometry (GC-MS) with headspace solid-phase micro extraction (SPME) method has been employed for the analysis of the flavor volatiles of three different rice cultivar, including two modified Iranian rice cultivars and Hashemi rice cultivar during gelatinization. The proposed combination provided a powerful system for easy and rapid screening of a wide range of flavors in fragrant rice samples. In order to optimize the different experimental parameters, the effect of fiber composition, water content of rice samples and equilibrium time were investigated. As a result, while the gelatinization was in progress, the amount of the volatile compounds was increased as well. All of the free flavor volatiles, the bound flavor components and the compounds formed by the thermal decomposition of the non-volatile constituents existing in rice could be liberated during the gelatinization process. Therefore, a broad range of the flavor volatiles of rice could be extracted, concentrated and identified. Altogether, 75, 55 and 66 components were identified for Hashemi, HD5 and HD6 rice samples, respectively, which 58 unique compounds were not detected previously. The identified volatile components in the three Iranian rice cultivars belong to the chemical classes of aldehydes, ketones, alcohols and heterocyclic compounds, as well as fatty acids and esters, phenolic compounds and hydrocarbons.

Edible coatings made from whey protein concentrate (WPC) and gellan gum (G) were investigated for their capacity to preserve the quality of Malus domestica cv Golab apples. WPC and gellan gum coatings at different concentrations plasticized with glycerol (Gly) were tested. Postharvest storage quality condition testes included weight loss, color and texture changes, titratable acidity and soluble solids content and consumer acceptance. The results indicated that WPC-gellan-coated fruits were rated highest for taste, glossiness, colour and overall acceptability and were lowest for weight loss in this study. Results also showed no significant difference in soluble solids content and titratable acidity between control and the coated apples after 4 weeks at 4oC.

The growth rate of two probiotic strains with documented health effects was studied in ultrahigh temperature treated milk separately and beside each other. The probiotic strains were Lactobacillus acidophilus (La-5) and Bifidobacterium lactis (Bb-12). Fermentation was followed for 12 h at 37oC and the samples were analyzed for pH, titratable acidity and viable counts of probiotic bacteria before incubation and at 2h intervals throughout the fermentation period. The obtained results showed that Lb. acidophilus had higher activity and growth rate than B. lactis when they were purely cultured in milk. Investigation on mixed culture inoculating the milk revealed that Lb. acidophilus had a stimulating effect on the growth rate of B. lactis, however, its growth wasn’t significantly affected by the presence of the latter bacteria.