Studies of the Interaction between Aspartame and Flavor Vanillin by High Performance Liquid Chromatography

The reaction between aspartame (APM) and vanillin was dependent on the molar ratio of reactants, temperature, water activity (a_w) and the presence of citric acid. The extent of the aldehyde-amine condensation reaction in the APM/vanillin (molar ratio 1:1) model system at 3.3°C, 25°C and 37.8°C and a_w of 0, 0.07, 0.18.032, 0.64, and 1.0 was monitored by high performance liquid chromatography (HPLC). The HPLC method could detect APM and vanillin simultaneously at ppm. Benzyl alcohol was used as the internal standard. This sensitive method measured the change at the picomole level. Schiff base formation followed second order kinetics for each temperature. The activation energy was 11.67 Kcal/mole for the APM/vanillin (1:1) system.     

Influence of Dairy Proteins on Aspartame Stability in the pH 6–7 Range

The effect of three commercial milk protein products on aspartame degradation was studied as a function of temperature (4, 30, 70, 80°C), pH (6 and 7), phosphate buffer concentration (0.01 M/L, 0.1 M/L) and protein (0–3%). Caseinates significantly decreased the pseudo-first order loss rate at low buffer concentration and higher temperature (70–80°C), whereas the rate was faster in the presence of a casein/ whey mixture. At high buffer concentration, the loss rate was not affected by protein. The protective effect may have been due to either a buffering capacity decrease caused by a protein/aspartame interaction that lowered pH or some unknown protein interaction. At 4 and 30°C, the loss rate was not affected by calcium caseinate.     

Chemical stability of encapsulated aspartame in cakes without added sugar

Encapsulated aspartame (APM), developed to protect the APM molecule during baking, has not been evaluated for stability during baking and subsequent product storage. Thus, the objectives of this project were to determine the APM recovery in various cake formulations after baking and to evaluate APM degradation kinetics during product storage. The recovery of encapsulated APM after baking was 33–34% while that of non-encapsulated APM was 22%. The addition of the acidulant glucono-delta lactone (GDL) to the formulation increased the recovery of encapsulated APM to 58%. The rate constants of APM degradation in the cakes with and without GDL at 22 °C were 0.0085 and 0.035 day⁻¹, respectively. By using 2.5% encapsulated APM in cupcake mixes for home preparation, enough APM should remain to provide adequate sweetness during typical product shelf life.     

Aspartame Degradation Kinetics as Affected by pH in Intermediate and Low Moisture Food Systems

Kinetics of aspartame degradation in low to intermediate moisture systems were evaluated by incorporating aspartame into agar/micro-crystalline cellulose model systems. They were prepared at pH 3, 5, and 7, equilibrated after freeze-drying to three water activities (0.34, 0.56, and 0.66), and stored at 25 to 45°C. Aspartame in such systems was most stable at pH 5 and became less stable as pH decreased or increased. As the molar buffer salt concentration increased, the rate of aspartame degradation increased. The activation energy ranged from 23 to 36 kcal/mole.     

EFFECTS OF LONG-TERM STORAGE ON QUALITY OF PROCESSED FOODS

Experiments were conducted on the effects of long-term storage at 4.4, 21.1, and 37.8°C temperatures on nutritional quality, physicochemical characteristics and organoleptic quality of 8 food packets (ready to eat individual ration items processed in flexible retortable pouches) of ham and chicken loaf, beef steak, beef stew, frankfurters, fruit cake, pineapple slices, cheese spread, and chocolate brownies. At 37.8°C storage life of cheese spread, pineapple slices, beef stew, chocolate brownies and fruit cake was 12, 12, 30, 30 and 30 months respectively. Ham and chicken loaf, beef steak, and frankfurters were acceptable after 37.8°C storage for 54 months, but frankfurters were near the borderline of rejection. The browning is usually associated with the high temperature storage of high sugar foods. Meat products except beef stew are apparently more stable than others at high temperature storage. The high temperature storage resulted in drastic loss of thiamin and ascorbic acid, significant loss of riboflavin and niacin, and discoloration and rancidity. Despite the losses of quality observed in all food packets stored at 21.1°C for 54 months, they were acceptable. Storage at 4.4°C for 54 months had very little effect on quality of the food packets and were highly acceptable.     

Drip loss,peroxidase and sensory changes in kiwi fruit slices during frozen storage

The biochemical, sensory and drip loss changes that occur during processing and prolonged frozen storage of kiwi fruit slices (cvs Abbott and Hayward) were studied. Fruit slices were frozen at ?40°C, packed in polyethylene bags and stored at ?18°C for 11 months. Maturity characteristics (pH, acidity, dry matter, soluble solids) were determined on raw fruit. Objective (proteins, peroxidase (EC 1.11.1.7) activity, drip loss) and subjective (sensory tests) analyses were carried out during processing and storage, and indicated a good quality of the frozen kiwi fruit slices after 11 months of storage. There were significant differences (P < 0.05) between the studied varieties with respect to drip loss during frozen storage and colour after 11 months. Best results were obtained with cv Hayward. This variety showed less drip loss after thawing and after 11 months storage presented the same green colour as after freezing, while cv Abbott became yellowish-green.     

Destructive Effect of Aspartame on Ascorbic Acid in Cu-catalyzed Solutions

The effect of aspartame on the early stage of ascorbic acid oxidation in solutions was studied by measuring ascorbic acid retention in an open system at 30°C and the oxygen uptake in a closed system at 33°C. Comparisons were also made between aspartame (0.06% and 0.12%) and sucrose (10% and 20%) in Cu-catalyzed and noncatalyzed solutions at 30°C. Copper activity in aspartame solution was measured by using a cupric ion selective electrode. Aspartame increased the rate of ascorbic acid oxidation in all tested solutions. In the presence of copper the oxidation rate of ascorbic acid was significantly higher in aspartame solutions than in sucrose solutions despite the fact that aspartame showed Cu-complex capacity in solution.     

Accelerated Kinetic Study of Aspartame Degradation in the Neutral pH Range

The degradation of aspartame in solution as a function of temperature (70–100°C), buffer concentration (0.01–0.1M phosphate), and pH (6–7) was studied in order to estimate losses during thermal processing and storage of aseptic milk-based drinks. Prior data have been mostly on acid carbonated beverages. First order rate constants were obtained in all the conditions with activation energies in the range 14–20 kcal/ mole. An increase in both pH and buffer concentration caused an increase in rate of loss. These data were used to predict losses that would occur during pasteurization and sterilization conditions. Experiments at 4 and 30°C showed significant losses would occur during 4 and 30°C temperature storage and extrapolation from high temperatures predicted faster degradation rates than those found.     

Kinetics of Decomposition of Aspartame Hydrochloride (Usal) in Aqueous Solutions

A scheme of aspartame hydrochloride (Usal) decomposition in relation to the pH and temperature which takes into account the possibility of phenylalanyl-aspartic acid dipeptide formation is suggested and experimentally confirmed. Aspartyl-phenylalanine and diketopiperazine were found to be the main decomposition products. The concentration of diketopiperazine increases and that of aspartyl-phenylalanine de-creases with increasing pH. At pH 2.9 less aspartyl-phenylalanine and more diketopiperazine is formed with increase in temperature; twice the concentration of phenylalanine methyl ester was found at 80° and 90°C when 50% of the Usal present in the medium was decomposed, as compared to that determined at 25° and 40°C. The distribution of the remaining products remained constant over the entire range measured.     

Growth of Clostridium perfringens spores inoculated in sous-vide processed Korean traditional Galbijjim under different storage conditions

To evaluate the microbiological safety of Korean traditional seasoned beef processed by sous-vide method, Clostridium perfringens spores were inoculated into the samples, and then germination and growth of spores were observed under different temperatures for days. Also, changes in pH, water activity, and salt contents were analyzed. As the results, there was no difference in water activity and pH of the samples during the storage at any temperature. However, salt contents of the samples significantly increased as storage time increased, and the storage temperature affected the change of salt contents. C. perfringens did not grow at 4 and 10°C for 24 days however, the bacterial growth was observed at 20°C after 2 days of storage. Based on these simulation tests, the microbiological safety of sous-vide processed galbijjim can be guaranteed at 4 and 10°C for 24 days even though the raw materials were contaminated by C. perfringens spores.     

Textural and sensory properties of Lal peda manufactured with artificial sweeteners and bulking agents

Lal peda is an Indian heat desiccated dairy food. High sugar content in Lal peda poses severe restriction in its consumption. Sugar was replaced with artificial sweeteners (aspartame, acesulfame‐k and sucralose) with the addition of bulking agents (Litesse and inulin) to provide a characteristic texture. Lal peda prepared using 25% Litesse and 0.17% aspartame gave an optimum product. HPLC analysis of artificially sweetened Lal peda samples revealed that aspartame in Lal peda was stable up to 6 days when stored at 20 and 37 °C. The acidic pH of Lal peda stabilised the aspartame and slowed down its degradation until 6 days. Neither inulin nor Litesse significantly altered the colour or sensory characteristics of Lal peda.     

Kinetics of the Maillard Reaction Between Aspartame and Glucose in Solution at High Temperatures

Comparison was made of the extent of browning during accelerated storage tests of glucose/aspartame and glucose/glycine model systems under steady state conditions of 70, 80, 90, and 100°C and an a_w of 0.80. Browning of aspartame followed zero order kinetics with a time to 0.1 absorbance units at 420 nm of 11.40, 5.3, 2.15 and 1.0 hr for each respective temperature. The activation energy (E_A) was 22.0 Kcal/mole for the glucose/aspartame system and 15.5 Kcal/mole for the glucose/glycine system. The temperature sensitivities (Q₁₀) for the model systems were 2.4 and 1.9, respectively. The predicted shelf life to reach 0.1 absorbance units in an aqueous system at 45°C is 62 days compared to the actual value of 60 days.     

Hot water and curing treatments reduce chilling injury and maintain post-harvest quality of 'Valencia' oranges

‘Valencia’ oranges [Citrus sinensis (L.) Osbeck] were harvested at optimal maturity and either dipped in hot water at 53 °C for 3 or 6 min or at 48 °C for 12 min or cured at 53 °C for 1 or 6 h or at 48 °C for 12 h. The fruits were not degreened, waxed or treated with any post‐harvest fungicides. All fruit samples were stored at 4 °C for 6 months following the treatments. Both hot water dip and curing treatments reduced chilling injury and decay when compared with the untreated control. The most effective treatments were curing of fruit at 53 °C for 6 h and at 48 °C for 12 h. Weight loss and juice yield were higher in cured fruits than those from other treatments, but the heat treatments had no consistent effects on titratable acid, soluble solids, ascorbic acid and peel colour. It was concluded that a pre‐storage hot water dip and curing at high temperatures might be beneficial in preventing chilling injury and decay of ‘Valencia’ oranges for 6 months of storage at 4 °C.     

Process development for stabilization of sugarcane juice using response surface methodology

Sugarcane juice is a very popular drink in India and other Asian countries, where sugarcane is an important crop. Since sugarcane juice spoils very quickly and there is a lack of research in this area, no commercialized sugarcane juices are available in India. Here, stabilized sugarcane juice was developed using response surface methodology. Total soluble solids, reducing sugar, total sugar, polyphenol oxidase activity, ascorbic acid, pH, optical density, transmittance, titrable acidity, microbiological properties, and sensory scores of the stabilized juice were evaluated using a Box–Behnken design. The composition was optimized and the sugarcane drink was further processed using blending and hot filling techniques. The processed juice was hot-filled into glass bottles under aseptic conditions. The predicted shelf life of the processed sugarcane juice was 3 months at 18 °C and 6 months at 10 °C.     

Simultaneous determination of neotame, alitame and aspartame in foods by HPLC

Simultaneous determination of three artificial sweeteners, neotame (NE), alitame (AL) and aspartame (APM) in various foods by high-performance liquid chromatography (HPLC) was developed. Chopped or homogenized samples were packed into cellulose tubing with 0.01 mol/L hydrochloric acid containing 10% sodium chloride, and dialyzed against 0.01 mol/L hydrochloric acid for 24-48 hours. The dialyzate was passed through an Oasis MCX cartridge, and the cartridge was washed with water and methanol. Then the three sweeteners were eluted from the cartridge with a mixture of 0.5 mol/L ammonium chloride-acetonitrile (3 : 2). The sweeteners were separated on a Cosmosil 5C18-AR column using a gradient mode with a mobile phase of 0.01 mol/L phosphate buffer (pH 4.0)-acetonitrile and were detected at 210 nm.The recoveries of NE, AL and APM from 8 kinds of foods spiked with 10 and 100 microg/g were 86-100% and 89-104%, respectively. The detection limits of NE, AL and APM were 1 microg/g in samples. Furthermore, the three sweeteners were successfully identified by using liquid chromatography with tandem mass spectrometry.     

Microbiological and physicochemical properties of dry‐cured neck inoculated with probiotic of Bifidobacterium animalis ssp. lactis BB‐12

The effect of inoculum level of Bifidobacterium animalis ssp. lactis BB‐12 probiotic strain and ripening period on the quality of dry‐cured neck was studied. The microbiological parameters (Enterobacteriaceae, LAB and TVC) and physicochemical attributes (pH value, a_w, TBARS index, colour) were determined directly after fermentation at 15 °C for 3 weeks, after 6 and 12 months of ripening at 4 °C. The highest LAB count and a lower pH value were found in the meat inoculated with probiotic strain at 6.6 log cfu g^?1 (B2) followed by inoculation with probiotic strain at 6.3 log cfu g^?1 (B1). Level of inoculation had not had an influence on water activity, TBARS index and total colour parameters. Changes of fat oxidation during half‐year of ripening were limited in probiotic meat samples compared to naturally fermented control meat (C). Based on the results, it can be concluded that the most favourable physicochemical and microbiological parameters of the dry‐cured neck were obtained after 6 months of ripening. At that time, the Bifidobacterium BB‐12 at both levels is a good potential starter for meat fermentation.     

Nutritional changes in maize (Zea mays) during storage at three temperatures

Nutritional changes in maize grains stored at 10, 25 and 45 °C for 6 months were studied. Significant decrease in pH and increase in titratable acidity was observed during storage of maize grains at 25 and 45 °C. Moisture contents of maize grains decreased by 25% at 25 °C and 38% at 45 °C after six months of storage. Total soluble sugars increased by 10.7% at 10 °C and 17.3% at 25 °C, whereas a 39.5% decrease was observed after 6 months storage at 45 °C. Total available lysine and thiamine contents in maize grains decreased by 13 and 9.26% at 25 °C, 16 and 20.4% at 45 °C, respectively, after 6 months of storage. Protein digestibility decreased by 5.19 and 9.0% at 25 and 45 °C, respectively, whereas decrease in starch digestibility was 9.86% at 25 °C and 15.1% at 45 °C on storage of maize grains for 6 months. However, no significant nutritional changes occurred during storage of maize grains at 10 °C.     

Poststorage Behavior of Apple Fruit After Low Oxygen Storage as Influenced by Temperatures During Storage and in Transit

‘Delicious’, ‘Newtown’ and ‘Granny Smith’ apples (Malus domestica Borkh.) maintained acceptable flesh firmness and high levels of titratable acids and soluble solids after 9 months of storage in 1% 0₂ at either 0°C or 3.3°C. Low-0₂-stored ‘Delicious’ were kept at 0°C for 6 wk without developing physiological disorders before or after 8 days of ripening at 20°C. Storage at 3.3°C caused ‘Delicious’ to soften faster during 6 wk of post-storage holding plus 8 days of ripening. ‘Newtown’ apples developed flesh browning and alcohol flavor after 9 months of low 0₂ storage at 0°C. ‘Newtown’ fruit stored at 3.3°C developed only minimal incidence of flesh browning and alcohol flavor. ‘Granny Smith’ fruit were free from scald, core flush, flesh browning and alcohol flavor after low 0₂ storage, regardless of storage temperature. However, core flush and flesh browning appeared when ‘Granny Smith’ were kept for 6 wk at 0°C plus 8 days at 20°C.     

Quality changes and storage life of common carp (Cyprinus carpio) at various storage temperatures

The shelf life and freshness changes in pond-grown common carp (Cyprinus carpio L) during storage at 0–2°C, 5–6°C and room temperature (26–29°C) were investigated by sensory, microbiological, physical and chemical analyses. The effect of gutting on the shelf life during storage at 0–2°C was examined. Iodine/starch and potassium sorbate were examined for their effects on shelf life of whole fish stored at 0–2°C and 5–6°C. Sensory results indicated that the whole fish had a maximum shelf life of 24 to 25 days at 0– 2°C. The life of the fish to the point beyond which it would be unsuitable for sale (commercial shelf life) was 17 days at 0–2°C. Storage at 5–6°C shortened shelf life 2- to 2.5-fold. At room temperature (26–29°C), spoilage was evident after 13 h. Gutting the carp shortened its storage potential at 0–2°C. Iodine treatment of this species stored at 0–2°C and at 5–6°C did not extend shelf life. The maximum shelf life of sorbate-treated fish at 0–2°C and 5–6°C was extended by 1–2 days, commercial shelf life by 3–4 days. Total volatile basic nitrogen, pH and penetrometer analyses were not reliable indicators of changes in freshness during shelf life. Thiobarbituric acid values were not useful as rancid odours or flavours were not detected during storage.     

Application of a biochemical time–temperature integrator to estimate pasteurisation values in continuous food processes

The microbiological safety of commercial fruit processes was evaluated using α-amylase time–temperature integrators (TTI) from either a Bacillus amyloliquefaciens or Bacillus licheniformis source. The TTIs were incorporated into silicone particles that were added to batches of fruit preparations to estimate the pasteurisation achieved during two different methods of continuous processing: a tubular heat exchanger and an ohmic column. Pasteurisation values (P-values) estimated with the TTIs represented the integrated thermal process at the core of 12-mm pear cubes for the tubular process of 12-mm strawberries, 12-mm pineapple and 10-mm blackcurrants for the ohmic process. The decimal reduction time at 85.0 °C (D₈₅) for the Bacillus amyloliquefaciens amylase was 6.8 min, with a kinetic factor (z-value) of 9.4±0.3 °C, and for the Bacillus licheniformis amylase the D₉₃ was 8.8 min with a z value of 9.1±0.3 °C. For the high-acid fruit products, the target P-value was equivalent to 5 min at 85 °C (T_ref=85 °C, z=10 °C). Amylase activity before and after processing was converted to P-values, with all of the processes showing a substantial safety margin, despite operating conditions that were deliberately set to represent the ‘worst case’ conditions. This method allowed P-value data to be collected under conditions that prevented the use of thermocouples.