A clean method for flow injection spectrophotometric determination of cyclamate in table sweeteners

Establishment of a new cell-based assay to quantitatively evaluate the sweetness of sugar and sugar alcohol

Sweetness is a crucial indicator for identifying sweeteners used for flavor regulation and nutritional matching of foods. This study established a new quantitative sweetness evaluation method based on a combination of transiently transfected sweet taste receptor cells (STRs) and human sensory evaluation. Here, nine different sweeteners were evaluated and 10 sensory difference intensities and their corresponding concentrations were obtained through sensory evaluation. Using the same concentration solution as in the sensory evaluation, the dosage-response curve and EC50 of the nine sweeteners were obtained by analyzing the intracellular calcium signal fluctuation of STRs. Data analysis revealed that the calcium signal intensity and sweetness intensity under the same concentration of sweetener presented a strong linear correlation (R2 > 0.9). Additionally, we found a favorable correlation (R2 = 0.8746) between the relative sweetness and EC50. These findings indicate that the quantitative evaluation of sweetness based on STRs could be a potential alternative to human sensory evaluation.

Rapid and sensitive quantification of cyclamate in beverages by miniature microplasma optical emission spectrometry

Most of the available methods for the quantification of cyclamate depend on laboratory instruments and their application in the field was limited. Herein, a simple and sensitive method was developed for the determination of cyclamate in beverage samples based on chemical vapor generation and miniature point discharge optical emission spectrometry (μPD-OES). The combination of headspace sampling and μPD-OES not only simplifies the separation process of cyclamate, improves sensitivity, and alleviates matrix interference but also eliminates the use of a bulky and expensive instrument. Under the optimal conditions, this method provided a limit of detection of 0.1 mg L^-1 comparable to or better than most reported methods. The method eventually was applied to 14 different beverages and cyclamate was found below the threshold set by Chinese Standards for Food Additives. The proposed method provides great potential for the field analysis of cyclamate in the supervision of food safety.

Analytical Methods for Determination of Non-Nutritive Sweeteners in Foodstuffs

Sweeteners have been used in food for centuries to increase both taste and appearance. However, the consumption of sweeteners, mainly sugars, has an adverse effect on human health when consumed in excessive doses for a certain period, including alteration in gut microbiota, obesity, and diabetes. Therefore, the application of non-nutritive sweeteners in foodstuffs has risen dramatically in the last decade to substitute sugars. These sweeteners are commonly recognized as high-intensity sweeteners because, in a lower amount, they could achieve the same sweetness of sugar. Regulatory authorities and supervisory agencies around the globe have established the maximum amount of these high-intensity sweeteners used in food products. While the regulation is getting tighter on the market to ensure food safety, reliable analytical methods are required to assist the surveillance in monitoring the use of high-intensity sweeteners. Hence, it is also necessary to comprehend the most appropriate method for rapid and effective analyses applied for quality control in food industries, surveillance and monitoring on the market, etc. Apart from various analytical methods discussed here, extraction techniques, as an essential step of sample preparation, are also highlighted. The proper procedure, efficiency, and the use of solvents are discussed in this review to assist in selecting a suitable extraction method for a food matrix. Single- and multianalyte analyses of sweeteners are also described, employing various regular techniques, such as HPLC, and advanced techniques. Furthermore, to support on-site surveillance of sweeteners’ usage in food products on the market, non-destructive analytical methods that provide practical, fast, and relatively low-cost analysis are widely implemented.

Determination of sweeteners in wine by liquid chromatography coupled with mass spectrometry (LC/MS)

Sweeteners are food additive substances that give a sweet taste to foods but their use in oenological practices is forbidden. Making use of the capabilities of liquid chromatography coupled with mass spectrometry, a method for wine analysis was developed and validated for the detection and quantitation of some of the most widely used sweeteners: aspartame, potassium acesulfame, sodium cyclamate, saccharin, sucralose and stevioside. A matrix-matched calibration was used for all compounds obtaining a linear concentration range from 50 μg/L to 1000 μg/L. The limit of detection ranged from 0.002 mg/L to 0.014 mg/L, and the limit of quantification varied between 0.005 mg/L and 0.048 mg/L. Precision and recovery were assessed for 50 μg/L, 250 μg/L and 1000 μg/L with repeatability and intermediate precision values from 0.6% to 21.6% and 2.7% to 26.4% respectively, and recoveries ranging from 60% to 126%. These results were achieved using minimal sample preparation with a fast and high throughput method that is applicable to a wide range of wine matrices.

Bienzymatic biosensor for rapid detection of aspartame by flow injection analysis

A rapid, simple and stable biosensor for aspartame detection was developed. Alcohol oxidase (AOX), carboxyl esterase (CaE) and bovine serum albumin (BSA) were immobilised with glutaraldehyde (GA) onto screen-printed electrodes modified with cobalt-phthalocyanine (CoPC). The biosensor response was fast. The sample throughput using a flow injection analysis (FIA) system was 40 h⁻¹ with an RSD of 2.7%. The detection limits for both batch and FIA measurements were 0.1 µM for methanol and 0.2 µM for aspartame, respectively. The enzymatic biosensor was successfully applied for aspartame determination in different sample matrices/commercial products (liquid and solid samples) without any pre-treatment step prior to measurement.

Green chemistry and the evolution of flow analysis. A review

Flow analysis has achieved its majority as a well-established tool to solve analytical problems. Evolution of flow-based approaches has been analyzed by diverse points of view, including historical aspects, the commutation concept and the impact on analytical methodologies. In this overview, the evolution of flow analysis towards green analytical chemistry is demonstrated by comparing classical procedures implemented with different flow approaches. The potential to minimize reagent consumption and waste generation and the ability to implement processes unreliable in batch to replace toxic chemicals are also emphasized. Successful applications of greener approaches in flow analysis are also discussed, focusing on the last 10 years.

A multicommuted stop-flow system employing LEDs-based photometer for the sequential determination of anionic and cationic surfactants in water

It has been developed an automatic stop-flow procedure for sequential photometric determination of anionic and cationic surfactants in a same sample of water. The flow system was based on multicommutation process that was designed employing two solenoid micro-pumps and six solenoid pinch valves, which under microcomputer control carry out fluid propelling and reagent solutions handling. A homemade photometer using a photodiode as detector and two light emitting diodes (LEDs) with emission at 470 nm (blue) and 650 nm (red) as radiation sources, which was tailored to allow the determination of anionic and cationic surfactants in waters. The procedure for anionic surfactant determination was based on the substitution reaction of methyl orange (MO) by the anionic surfactant sodium dodecylbenzene sulfonate (DBS) to form an ion-pair with the cetyl pyridine chloride (CPC). Features such as a linear response ranging from 0.35 to 10.5 mg L(-1) DBS (R=0.999), a detection limit of 0.06 mg L(-1) DBS and a relative standard deviation of 0.6% (n=11) were achieved. For cationic surfactant determination, the procedure was based on the ternary complex formation between cationic surfactant, Fe(III) and chromazurol S (CAS) using CPC as reference standard solution. A linear response range between 0.34 and 10.2 mg L(-1) CPC (R=0.999), a detection limit of 0.05 mg L(-1) CPC and a relative standard deviation of 0.5% (n=11) were obtained. In both cases, the sampling throughput was 60 determinations per hour. Reagents consumption of 7.8 microg MO, 8.2 microg CPC, 37.2 microg CAS and 21.6 microg Fe(III) per determination were achieved. Analyzing river water samples and applying t-test between the results found and those obtained using reference procedures for both surfactant types provide no significant differences at 95% confidence level.