Microwave Dehydration of Borax: Characterization,Dehydration Kinetics,and Modelling

Glass Physics and Chemistry - In the present study, borax (Na2B4O7·10H2O) was dehydrated using microwave radiation and the dehydration rate curves were calculated. The kinetic parameters and...     

Ohmic Tempering of Frozen Potato Puree

Frozen potato puree samples were tempered using an ohmic heating technique. Three salt concentrations (0.50, 0.75, and 1.00 %) and three frequency levels (10, 20, and 30 kHz) were used as experimental variables, and the effects of salt concentration and frequency on ohmic tempering were investigated. Temperature, electrical current, and voltage were measured during the ohmic tempering. Electrical conductivities were evaluated based on the sample geometry and the ohmic heating principle. Increasing the salt concentration and/or frequency increased the electrical conductivity and heating rate, and hence contributed to decreasing the tempering time for the frozen potato puree samples. The tempering time was lowest with the highest salt concentration employed, and longest for the lowest salt concentration and frequency. Temperature differences within the sample during ohmic heating were found to be lowest when employing 0.50 % salt concentration and 10 kHz frequency.     

An evaluation of the retention of quality characteristics in fresh and freeze-dried alpine strawberries

Alpine strawberries (Fragaria vesca) are used in fruit juice, marmalade, or jam production and as a result have economical importance in food sector. The fresh alpine strawberries have a tendency to lose their quality in a few days as a result of high water loss and spoilage. In this paper, the results of a study on the effects of freeze drying process on the characteristics of the alpine strawberries, such as firmness, sugar content, pH, colour, weight loss, dissolved solids, anthocyanin and vitamin C content with reference to the fresh, are reported. Freeze‐drying indicated no difference in the characteristics of the alpine strawberries when compared with the fresh. It is found that a slight acid or base addition onto the rehydrated alpine strawberry juice preserved the stability of pigments and the colour. In addition, the rehydrated alpine strawberry juice exhibited an antimicrobial activity towards an important foodborne pathogen, Enterobacter faecium ATCC 6057.     

Studies on an inhibitor produced by lactic acid bacteria of wines on the control of malolactic fermentation

Malolactic fermentation is the microbiological process in wines, where lactic acid bacteria (LAB) govern the process of converting L-malic acid into L-lactic acid. During this process a high microbial load of LAB may lead to an unwanted spoilage phenomena by formation of excessive amounts of undesirable flavor compounds. This study is mainly focused on the isolation of LAB from the native flora of the wine, which has an inhibitory potential against malolactic activity of LAB inherent in wines. An isolate of Leuconostoc mesenteroides subsp. cremoris was found to produce an inhibitory compound against the LAB of wines. This compound was found to be a bacteriocin-like inhibitory substance (BLIS), which has a molecular weight of 32,000 Da, and it was shown that this BLIS was effective in the control of malolactic fermentation.     

Development of antioxidant food packaging materials with controlled release properties

In this study, cellulose acetate (CA) films with different morphological features were prepared in order to control the release rates of low molecular weight natural antioxidants, L-ascorbic acid and L-tyrosine. Increasing CA content in the casting solution decreased the average pore size and porosity of the films, thus, reduced the diffusion rates of both antioxidants through the films. Although both antioxidants have similar molecular weights, L-tyrosine released into water much more slowly than L-ascorbic acid. The highest antioxidant activity in release test solutions was observed with highly porous L-tyrosine containing films. However, when the porosity of the films reduced, the antioxidant activity of L-ascorbic acid released into solution was found to be higher due to trapping of significant amount of L-tyrosine in dense films. The use of different antioxidants caused different changes in morphological and mechanical properties of the CA films. Varying the structural features of the films with the preparation conditions or using different surfaces of the films allowed the controlled release of each antioxidant.     

DETERMINATION OF THE EFFECT OF LEMON ADDITION UPON ELEMENT CONCENTRATIONS IN TEA

Consumption of tea is a popular tradition in Turkey. In this article, non essential and toxic element concentrations were determined in infusions and lemon added infusions in widely consumed Turkish teas (black, earl grey, and green tea). Element concentrations were found to be in the order of aluminum > nickel > barium in black and earl grey teas. In green tea, the order was changed to aluminum > nickel > lead > barium. The concentrations of arsenic and antimony were below the detection limit of the inductively coupled plasma optical emission spectrometry method employed. The addition of lemon increased aluminum, cadmium, and lead concentrations in all teas whereas nickel concentration increased in black and green tea but decreased in earl grey. The barium concentration was same at all tea samples. In comparison with the recommended daily allowance ratios, the amount of aluminum consumed is between 13.167–24.396% in males and 17.556–32.528% in females for people who consume 200 mL of teas daily. Other elements (cadmium, lead, nickel, barium) which are a concern for tea consumption were determined and the hazard index of daily tea drinking was found to be in the safe range except for green tea with lemon addition.     

Preservation of quinces by the combination of an edible coating material, Semperfresh, ascorbic acid and cold storage

Quinces (Cydonia oblonga, Miller) have a crucial economic value owing to their demand as jams or compote, and their high vitamin and fiber content. A preservation method for extending the shelf life of quinces by the combination of an edible coating material, Semperfresh, ascorbic acid and cold storage was designed in this study. The ascorbic acid content, firmness, total sugar, pH, titratable acidity, respiration rate, soluble solids, weight, total humidity, mold, yeast, and total mesophilic aerobic bacteria count were monitored. It was found that the triple combination of Semperfresh, ascorbic acid and cold storage provides high microbial, chemical and sensorial qualities for the quinces, leading to an extension in shelf life when compared with untreated quinces.     

Encapsulation of Food Ingredients Using Nanoliposome Technology

Nanoliposomes are microscopic vesicles composed of phospholipid bilayers entrapping one or more aqueous compartments. Their unique properties have triggered numerous applications in several scientific and technological fields. Nanoliposomes can provide controlled release of various bioactive agents, including food ingredients and nutraceuticals, at the right place and the right time. Therefore, they increase the effectiveness and cellular uptake of the encapsulated material. Reactive, sensitive, or volatile additives (vitamins, enzymes, antioxidants, slimming agents, etc.) can be turned into stable ingredients using nanoliposomes. This article reviews various aspects of nanoliposomes including currently available preparation methods, and their application in food technology.     

Effects of different emulsifier types,fat contents,and gum types on retardation of staling of microwave‐baked cakes

The effects of different types of emulsifiers, gums, and fat contents on the retardation of staling of microwave‐baked cakes were investigated. First, different types of emulsifiers (DATEM, Lecigran, and Purawave) at three different fat contents (50%, 25%, and 0%) were added to cake formulations to retard staling of microwave‐baked cakes. Then, three types of gums (guar gum, xanthan gum, and methylcellulose) were added to the optimum formulations chosen. As a control, cakes formulated without any emulsifier or gum addition and baked in an conventional oven at 175°C for 25 min was used. Weight loss, firmness, soluble starch and amylose content of the cakes were used as the indicators of staling criteria. Cakes were baked in a microwave oven for 1.5 min at 100% power. Variation of staling parameters during storage of cakes followed zero‐order kinetics. Use of emulsifiers and gums helped to retard staling of microwave‐baked cakes. Fat content was found to be a significant factor in affecting variation of firmness and weight loss of the cakes during storage. DATEM and Purawave were the most effective emulsifier types. Using gums in combination with emulsifiers gave better moisture retention and softer cakes than using gums alone.     

Effects of a bacteriocin-like substance produced by Leuconostoc mesenteroides subsp. cremoris on spoilage strain Lactobacillus fructivorans and various pathogens

Certain lactic acid bacteria present in the natural flora of the wine fermentation medium perform the malolactic fermentation process and other biochemical activities which lead to the formation of the outstanding aroma and bouquet of wine. However, because of the spoilage phenomena caused also by certain lactic cultures, off‐odours formed via metabolic side reactions cause severe economic losses in the wine industry. Several control mechanisms were introduced in order to eliminate these spoilage cultures, but none of these has been implemented as an efficient and healthy process. A partially purified bacteriocin‐like inhibitory substance (BLIS) with a molecular weight of 32 000 Da, obtained from a Leuconostoc mesenteroides subsp. cremoris isolate belonging to the native flora of wines of the Cappadocia region, was studied for its inhibitory activity on the spoilage strain, Lactobacillus fructivorans, isolated from the same wine flora and several other pathogens, and was found to be efficient in eliminating both the spoilage strain and the pathogens.