Changes In Turbidity Research Articles

Changes in turbidity along Ganga River using Sentinel-2 satellite data during lockdown associated with COVID-19

India had announced the longest ever lockdown from 25 March 2020 to 14 April 2020 amid COVID-19 pandemic. It was reported that the water quality of the Ganga River has improved as compared to regular during this country-wide lockdown. In the present study, an attempt has been made to study the change in water quality of the river in terms of turbidity purely through remote sensing data, in the absence of ground observations, especially during this time period. The change in spectral reflectance of water along the river in the visible region has been analyzed using the Sentinel-2 multispectral remote sensing data at Haridwar, Kanpur, Prayagraj, and Varanasi stretches of the river. In the present study, it was found that the red and NIR bands are most sensitive, and can be used to estimate the turbidity. Further, the temporal variation in turbidity was also analyzed through normalized difference turbidity index at each location. It was observed that the turbidity in the river has reduced drastically at each stretch of the river. The study elicited that the remote sensing approach can be used to make qualitative estimates on turbidity, even in the absence of field observations.

Complementary responses of stream fish and benthic macroinvertebrate assemblages to environmental drivers in a shale-gas development area

Shale-gas production could impact freshwater quality through contamination of the physical and chemical habitat (e.g., fracturing fluids, untreated or treated effluent) or development-related impacts. Despite environmental concerns, information is lacking to support biomonitoring as a diagnostic tool to assess impacts of shale-gas production. We characterized water quality and biota in areas of high shale gas potential (Early Carboniferous bedrock in New Brunswick, Canada) and surrounding geologic areas, and we assessed patterns in benthic macroinvertebrate (BMI) and fish assemblages. Early Carboniferous stations differed primarily based on water chemistry, and BMI were associated with a gradient in conductivity and temperature across geologic classes. Concordance analysis indicated similar classification of stations by both organism groups, though fish were more related to turbidity and nutrients. Concordance among fish and BMI was strongest at high conductivity, Early Carboniferous stations. These results suggest that geology plays a strong role in driving abiotic habitats and biotic communities of streams, even at small spatial scales. Furthermore, they suggest BMI and fish can provide complementary information for biomonitoring in shale-gas development areas, with BMI responding to increased ion concentrations from surface water contamination, and fish responding to changes in nutrients and turbidity resulting from development.

Using measures of water quality to narrow down the postmortem submersion interval (PMSI) in water

The purpose of this study was to explore the use of water quality parameters as proxy variables for establishing a timeline for the postmortem submersion interval (PMSI). This research was conducted using mice in water samples collected from the Schuylkill river in Philadelphia, US, as well as deionized water for control. Parameters were monitored from initial placement of the specimens in water to the completion of the experiment three months later. These parameters included pH, dissolved oxygen (DO), turbidity, conductivity, total organic carbon (TOC), nitrite, nitrate, and heterotrophic bacteria. In addition, qualitative observations of the specimens were made using Total Aquatic Decomposition Score (TADS). Peak changes in conductivity, turbidity, and TOC parameters coincided with a TADS of 7–9, indicating a partially decomposed carcass. These results preliminarily suggest that standard, easy to measure water quality parameters could serve as potential indictors in estimating PMSI in surface water bodies, however more experimental and field studies are needed to replicate results and validate findings.

Application of high-frequency ultrasound standing waves for the recovery of lipids from high-fat dairy effluent.

Effect of high-frequency ultrasonication was examined on wastewater of a cheese manufacturing plant. Tests were carried out at two frequencies (500kHz and 1MHz) and two temperatures (22 and 40°C). Samples were subjected to different energy densities; 7.5, 30.2, 60.5 and 121.0J/mL at 500kHz and 7.9, 31.7, 63.4 and 126.8J/mL at 1MHz to observe the creaming and recovery of lipid. These energy densities correspond to 30, 120, 240 and 480s of sonication. Sonication was performed using a single plate transducer and reflector system at 40W to create standing wave to coalesce and flocculate lipid globules. Recovery was higher at 40°C after 480s of sonication at both frequencies (77% at 500kHz and 75% at 1MHz). The lowest recovery of 47% was observed at 500kHz and 22°C at all applied energy densities. Changes in particle size and turbidity in the bottom aliquot indicated that high-frequency ultrasound caused coagulation and aggregation and settling of colloidal particles. Increase in particle size was observed to be highest at 1MHz, 40°C and 480s of sonication. These results confirm that high-frequency ultrasound standing wave technology can be used to recover lipid from high-lipid dairy wastewater including that from cheese manufacturing.

Impact of Adding Sodium Chloride to Change of Turbidity and Iron Concentration on Treatment Waste Water Using Electrocoagulation Process

The treatment waste water of electrical industry was investigated through electrocoagulation process. The study was conducted by flowing of 4,5 liters of waste water into the three cells of electrocoagulation process tank. Each cell is filled 1.5 liters of waste water without adding of sodium chloride (NaCl). The electrocoagulation process is carried out at a voltage of 12 V and interval time for observation of electric current, turbidity and iron cocentration in the water is done every 10 minutes. Subsequently, the same procedure was performed and added the sodium chloride with variation of weight of 0.5, 1.0 and 1.5 gram. To determine change value of electrical current, turbidity, metals pollutant was done using Ampere meter, turbidity meter and AAS respectively. The best conditions are recommended for use 0.5 gram of sodium chloride and 110 minutes for processing time. Under these conditions the voltage of 12 V and the current is 1.13 A. In this condition the turbidity can be removal from 44.10 to 2.35 NTU or 94.33 % and iron concentration from 1.21 to 0.29 mg/L or equal to 76.03 %. In conclusion adding of sodium chloride in simultaneous process of electrocoagulation and strerilization can cause increase of the electric current and accelerate the removal of pollutants in the wastewater.

Statistical optimisation of laccase production by isolated strain Aspergillus flavus PUF5 utilising ribbed gourd peels as the substrate and enzyme application on apple juice clarification

ABSTRACT In the current study laccase was produced by the isolated strain Aspergillus flavus PUF5 through solid-state fermentation (SSF) using waste ribbed gourd peels as substrate. During the statistical optimisation process, influencing fermentation factors among eleven selected variables were identified using Plackett–Burman design. Among them, fermentation time (144–192 h), medium pH (3.0–7.0), concentration of starch (0.5–1%) and concentration of peptone (0.2–0.8%) were vital influencing parameters. Furthermore, the shared effects of those variables were studied following Box–Behnken design. Optimised states of selected variables were fermentation time (168 h), medium pH (4.9), concentration of starch (0.61%) and peptone (0.51%) with predicted and observed activity of laccase 174.3 and 168.9 U/g, respectively. This laccase production under optimised condition was about 3.5-fold more that the unoptimised medium. The laccase obtained through SSF was tested for its suitability in the clarification of apple juice. During enzymatic oxidation, the changes in colour, turbidity, phenolics and flavonoids in apple juice were estimated and compared with untreated sample. Results showed a significant reduction in phenolic and flavonoid content in the fruit juice during the oxidation process. The turbidity in the juice was also decreased, which indicated the suitability of the laccase form A. flavus PUF5 in fruit juice clarification.

Lipid shape determination of detergent solubilization in mixed-lipid liposomes

The effects of lipid charge and head group size on liposome partitioning by detergents is an important consideration for applications such as liposomal drug delivery or proteoliposome formation. Yet, the solubilization of mixed-lipid liposomes, those containing multiple types of lipids, by detergents has received insufficient attention. This study examines the incorporation into and subsequent dissolution of mixed-lipid liposomes comprised of both egg phosphatidylcholine (ePC) and egg phosphatidic acid (ePA) by the detergent Triton-X100 (TX). Liposomes were prepared with mixtures of the two lipids, ePC and ePA, at molar ratios from 0 to 1, then step-wise solubilized with TX. Changes in turbidity, size distribution, and molar heat power at constant temperature throughout the solubilization process were assessed. The data suggest that the difference in lipid shapes (shape factors = 0.74 and 1.4 [1,2]) affects packing in membranes, and hence influences how much TX can be incorporated before disruption. As such, liposomes containing the observed ratios of ePA incorporated higher concentrations of TX before initiating dissolution into detergent and lipid mixed-micelles. The cause was concluded to be increased mismatching in the bilayer from the conical shape of ePA compared to the cylindrical shape of ePC. Additionally, the degree to which ePA is approximated as conical versus cylindrical was modulated with pH. It was confirmed that less conical ePA behaved more similarly to ePC than more conical ePA. The understanding gained here on lipid shape in liposome incorporation of TX enables research to use in vitro liposomes that more closely mimic native membranes.

A Feature‐Based Procedure for Detecting Technical Outliers in Water‐Quality Data From In Situ Sensors

AbstractOutliers due to technical errors in water‐quality data from in situ sensors can reduce data quality and have a direct impact on inference drawn from subsequent data analysis. However, outlier detection through manual monitoring is infeasible given the volume and velocity of data the sensors produce. Here we introduce an automated procedure, named oddwater, that provides early detection of outliers in water‐quality data from in situ sensors caused by technical issues. Our oddwater procedure is used to first identify the data features that differentiate outlying instances from typical behaviors. Then, statistical transformations are applied to make the outlying instances stand out in a transformed data space. Unsupervised outlier scoring techniques are applied to the transformed data space, and an approach based on extreme value theory is used to calculate a threshold for each potential outlier. Using two data sets obtained from in situ sensors in rivers flowing into the Great Barrier Reef lagoon, Australia, we show that oddwater successfully identifies outliers involving abrupt changes in turbidity, conductivity, and river level, including sudden spikes, sudden isolated drops, and level shifts, while maintaining very low false detection rates. We have implemented this oddwater procedure in the open source R package oddwater.

The effect of initial weight of seedlings grafted from tissue-cultured and local strain seedlings on growth and carrageenan content of the Red Seaweed (Kappaphycus alvarezii) using a grafting method

A grafting experiment using tissue-cultured and local strain Kappaphycus alvarezii seedlings was conducted from January to April 2019 and consisted of two steps. Firstly, grafting and propagating the seedlings using three different initial weights (IW) of 10, 15 and 20 g. Secondly, a culture experiment using the new seedlings produced from the first step. Seedlings were completely attached to each other after 18 days following the first step with a mean 75.0% grafting rate. The new seedlings were then cultured for 45 days using a long line method. The highest daily growth rate (DGR) was 4.36 %.day-1 obtained from 20-g IW while the lowest DGR was 4.01%.day-1 from 15-g IW. It was found that rapid changes in water salinity and turbidity may affect the success in terms of grafting rate and DGR. The ratio of fresh weight (FW) to dry weight (FW:DW) showed no significant differences among treatments although the 20-g IW showed the highest FW:DW ratio (8.21: 1) followed by 15-g IW (7.87:10) and 10-g IW (6.63:1). In contrast, 10-g IW and 15-g IW showed a significant difference in term of carrageenan content from 20-g IW. The 10-g IW carrageenan content was highest (40.38%) followed by 15-g IW (40.25%) and 20-g IW (38.34%). Salinity was 24-32 ppt, temperature was 29-31 °C. Nitrate and phosphate were 0.324-0.420 mg.l-1 and 0.180-0.538 ppm, respectively, while turbidity range was 3,128-9,336 NTU. In conclusion, for this method of grafting, it is recommended to use 20-g initial weight.

Effects of Temperature on the Transport of Suspended Particles Through Sand Layer During Groundwater Recharge

This paper presents an experimental study of suspended particle transport through sand layer using a new self-developed sand layer transportation-deposition testing system, and the study aims to identify the effects of temperature on the transport of suspended particles through porous medium. Four typical temperatures (5 °C, 15 °C, 25 °C, and 35 °C) were considered in our study, and the experiments were conducted under four size compositions and three flow velocities (1.5 cm/s, 0.2 cm/s, and 0.04 cm/s). The tests were conducted using quartz sand as the porous medium and quartz powder as particles to monitor the change in turbidity under the different conditions. The breakthrough curves were analyzed, and the results demonstrated that changes in temperature can affect the breakthrough curves, especially at the peak. The influence is particularly significant under lower flow velocities and for smaller particles. In regard to the influence factors on the transport process, water viscosity and adsorption effect can be regarded as promoting factors, while kinetic energy of particles can be classified as constraining factors.

Inactivation of Escherichia coli and Salmonella in liquid egg white by pulsed UV light and its effects on quality

AbstractThis study evaluated the pulsed UV light treatment for the inactivation of Escherichia coli K12 and Salmonella Enteritidis in liquid egg white. Three parameters (treatment time, volume of liquid egg white, and distance from the sample to the pulse UV strobe) have been optimized for log reductions of microorganisms using response surface methodology. The maximum log reductions obtained after 40 s of treatment time at a 5 cm of distance (the energy dose equals 45.6 J/cm2) were 1.28 log CFU/ml of E. coli K12 and 1.98 log CFU/ml of S. Enteritidis in 5 ml of fresh liquid egg white. A significant temperature increase of the egg white sample (from 24 to 70°C) was observed at the extreme treatment condition (5 cm, 40 s). Quality evaluations indicate that pulsed UV light does not change foaming ability or foam stability of liquid egg white. However, the changes in pH, lipid oxidation, turbidity, and color of the egg white were correlated with the intensity of the treatment.Practical applicationsHeat pasteurization is currently being used to decontaminate liquid egg white. However, alternative methods are desired to improve decontamination as well as maintain the quality of liquid egg white. This study demonstrated the potential of pulsed UV light for the inactivation of pathogens in liquid egg white.

Changes in Permeability and Benthic Environment of Coastal Sediment based on Calcium Salt Supplier

Kim, K.M., Suh, Y.C., Lee, I.C., Choi, C.G. and Kim, K.H., 2019. Changes in permeability and benthic environment of coastal sediment based on calcium salt supplier. In: Lee, J.L.; Yoon, J.-S.; Cho, W.C.; Muin, M., and Lee, J. (eds.), The 3rd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 91, pp. 311-315. Coconut Creek (Florida), ISSN 0749-0208.This study aims at the remediation of anaerobic coastal sediment using a calcium supplying material. For the calcium supplying material, granulated coal ash (GCA) was developed using coal fly ash. We hypothesized that calcium ions supplied from GCA can improve the water flow conditions such as the shear frictional force or pore plugging. A change in turbidity of the clay suspension in varying ionic solutions confirmed that sodium ions from coastal sediment disperse the clay particles, whereas calcium ions released from GCA aggregate the clay particles following the electrical double layer theory. These electrical phenomena affect the change in permeability of a cohesive sediment, and GCA increases the permeability coefficient of the cohesive sediment by 3.5 times compared to the control case. According to the results of the sediment incubation experiment, the calcium concentration in the pore water statistically increased (p<0.05), whereas the sodium concentration statistically decreased (p<0.05), resulting in favorable conditions for pore water flows. The ORP increased from -25.9 to 46.9 mV by the activated pore water flows, resulting in aerobic conditions. From these results, we concluded that GCA, a calcium supplier, generates pore water flows, remediating anaerobic cohesive sediment.

Regulation of Spatial Changes in Phytoplankton Community by Water Column Stability and Nutrients in the Southern Yellow Sea

AbstractThe southern Yellow Sea (SYS) shows extensive spatial variations in water masses, particularly YS Warm Current Water (YSWCW) and YS Coastal Current Water in cold and YS Bottom Cold Water (YSBCW) and Changjiang Diluted Water in warm seasons. These hydrographic processes result in significant spatial changes in nutrients, stratification, and turbidity, which may highly regulate phytoplankton distribution in the SYS. Here, we provide high spatial resolution data sets of phytoplankton in the SYS in all seasons during 2011–2012. Diatoms thrived in eutrophic Changjiang Diluted Water and YS Coastal Current Water regions. Notably, benthic/meroplanktonic diatoms, including Paralia sulcata and Rhaphoneis spp., were dominant near the Changjiang Estuary and Subei Shoal. However, cryptophytes and haptophytes were dominant in oligotrophic offshore regions controlled by YSWCW and YSBCW. Phytoplankton abundance and chlorophyll a were considerably lower in the YSWCW and YSBCW than in other regions, and the community composition varied significantly among regions. Algal blooms were observed off the SYS coast in spring and near the Changjiang Estuary in summer, which were characterized by abundant nutrients, low turbidity, and a relatively stable water column. Canonical correspondence analysis demonstrated that stratification in cold and nutrients in warm seasons were most important variables correlated with phytoplankton community. Variation partitioning analysis confirmed that spatial changes in phytoplankton community composition were largely structured by nutrients rather than by physical factors in all seasons except winter. Our findings highlight the significance of water column stability and nutrients associated with water mass variation in shaping spatial changes of phytoplankton community in the SYS.

Analysis and modelling of the regeneration process of chemical solutions after brewing equipment cleaning in a Cleaning in Place system based on changes in turbidity

Abstract The study presents the results of an analysis concerning the impact of temperature on the regeneration of the cleaning solution after cleaning the installations of a brewery in a Cleaning in Place system and based on the obtained results optimize the process of chemical solutions regeneration. The solutions were collected from a production plant after the process of cleaning and subjected to 12-h sedimentation. During the sedimentation process in different temperatures, the changes in turbidity were determined, as this represents a purity criterion for chemical solutions. The results were subjected to statistical analysis. The standard deviations of the dispersion in relation to the obtained averages were determined and Tukey's multiple comparisons test was used to identify the significance of the influence of temperature on the purity of the final solution. Based on the obtained results, a non-linear regression model was developed which constituted a mathematical description of the process of sedimentation of chemical solutions after the process of cleaning brewing installations M = f(t,T). The exponential function was assumed to describe the regeneration process. Numerical calculations were carried out based on the nonlinear least squares method using the Gauss-Newton algorithm. Finally, the surface area of the response of the relationship between the time and temperature of sedimentation and the turbidity of solutions was designated. The research results indicated that an appropriate temperature of chemical solutions during their regeneration can significantly influence their final purity degree and the duration of the regeneration process. In the case of sodium hydroxide after cleaning of mash filter, its regeneration is preferably carried out at a temperature below 40 °C, whereas in the case of sodium hydroxide after cleaning of the vessels a temperature of above 50 °C is desirable. Statistical analysis also showed that an acidic solution is best regenerated at 50 °C.

UV-C light inactivation of single and composite microbial populations in tangerine-orange juice blend. Evaluation of some physicochemical parameters

This study was aimed at investigating the response of single Saccharomyces cerevisiae KE162 or composited with three cocktails in a turbid orange-tangerine juice blend processed by UV-C 1720mJ/cm2, 20°C). Additionally, changes in polyphenol content (PC), total antioxidant activity (TAA), and some physicochemical parameters were analyzed after treatment. S. cerevisiae was combined with cocktails of yeasts (YC), Escherichia coli or native flora isolated from orange-tangerine peel. The adequacy of three conceptually different predictive models was also assessed. Overall, microbial inactivation curves displayed, in general, sigmoidal shape, with a significant shoulder. Moderate inactivation of single or composited inocula was achieved after UV-C treatment (3.9–4.3 log reductions). Coroller model allowed the best fit and the most accurate parameters’ estimation. S. cerevisiae in presence of background cocktails was less sensitive to UV-C, probably due to the interfering populations that hindered light path. UV-C treated juice displayed similar PC (0.61±0.06mg GAE/mL) and TAAABTS (0.82±0.14mg TroloxEq/mL) values than untreated juice (PC=0.63±0.10mg GAE/mL; TAAABTS=0.58±0.40, TAADPPH=3.69±0.14mg TroloxEq/mL), and a slight decrease in TAADPPH (2.77±0.06mg TroloxEq/mL), according to MANOVA. In addition, no changes in colour, acidity, turbidity, °Brix and pH (p>0.05) were recorded after UV-C exposure.

A Low-Cost Continuous Turbidity Monitor.

Turbidity describes the cloudiness, or clarity, of a liquid. It is a principal indicator of water quality, sensitive to any suspended solids present. Prior work has identified the lack of low-cost turbidity monitoring as a significant hurdle to overcome to improve water quality in many domains, especially in the developing world. Low-cost hand-held benchtop meters have been proposed. This work adapts and verifies the technology for continuous monitoring. Lab tests show the low-cost continuous monitor can achieve 1 nephelometric turbidity unit (NTU) accuracy in the range 0–100 NTU and costs approximately 64 USD in components to construct. This level of accuracy yields useful and actionable data about water quality and may be sufficient in certain applications where cost is a primary constraint. A 38-day continuous monitoring trial, including a step change in turbidity, showed promising results with a median error of and NTU for two different monitors. However, some noise was present in the readings resulting in a standard deviation of and NTU, respectively. The cause was primarily attributed to ambient light and bubbles in the piping. By controlling these noise sources, we believe the low-cost continuous turbidity monitor could be a useful tool in multiple domains.

Application of Remote Sensing to Identify and Monitor Seasonal and Interannual Changes of Water Turbidity in Yellow River Estuary, China

AbstractWater turbidity is an important indicator for water security and environmental security in the Yellow River estuary. However, due to the complex terrain and harsh climatic environment, it is difficult to monitor the water turbidity over the complex surface of the estuary. In this study we applied a self‐organizing map clustering method, an artificial neural network clustering method, to extract turbidity patterns from the long‐term remote sensing data sets in the Yellow River estuary. Based on the Moderate Resolution Imaging Spectroradiometer data from 2000 to 2015, six turbidity patterns were identified by using the self‐organizing map clustering method: high turbidity pattern, moderate turbidity pattern, low turbidity pattern, very low turbidity pattern, extreme high turbidity pattern and sea ice pattern, and the first four patterns appear every year. All patterns have significant seasonal characteristics, and monthly turbidity is dominated by one of these turbidity patterns. The water turbidity in the estuary has decreased in the past 16 years, and the interannual variation of the turbidity pattern is the result of the combination of the sediment transported into the sea by the Yellow River and the wind and waves on the sea surface.

Temperature and surface runoff affect the community of periphytic diatoms and have distinct effects on functional groups: evidence of a mesocosms experiment

In response to climate change it is expected an increase in temperature and precipitation in subtropical regions of South America. Precipitation increases surface runoff, which leads to an increased input of nutrients and suspended solids in freshwater ecosystems, resulting in changes in turbidity and water color. We analyzed the effects of increased temperature and surface runoff (simulated by soil addition) on freshwater periphytic diatom communities through a bi-factorial (temperature: ambient and increased in 2.5°C; runoff: present and absent) experiment, simulating lentic waters in mesocosms of polyethylene. Diatom species richness was reduced by increased temperature. Further, runoff reduced species richness of high-profile and motile diatoms, while the interaction between temperature and runoff explained differences in relative abundances of the high-profile and planktonic (occurring occasionally entangled in the periphyton matrix) functional groups. The low-profile group was positively affected by soil addition. Temperature and runoff also affected the composition of all functional groups (low-profile, high-profile, motile, and planktonic diatoms). These results indicated different responses of diatom functional groups to temperature increase and surface runoff, showing the importance of considering ecological differences among functional groups to evaluate the possible consequences of climate change.

Complex coacervates formation between gelatin and gum Arabic with different arabinogalactan protein fraction content and their characterization

This work aimed to investigate the possible impact of the chemical composition of gum arabic (GA) on the interactions and complexation mechanism with gelatin (G). For this purpose, two gum arabic samples were selected differing in the content of their arabinogalactan protein fraction (AGP), i.e. low (7%, GA7) and high (14%, GA14). The complex coacervates formation process was studied as a function of pH (from 7 to 2.4) and G:GA mixing ratio (1:2, 1:1, 2:1, 4:1, 6:1 w/w) by following changes in turbidity, ζ-potential and absorption of methylene blue – biopolymers mixtures. The complexation between the biopolymers (G-GA7 and G-GA14) was found to be stronger at a ratio of 1:1 and pH 3.7, where the highest yield (∼71%) was observed. The formed coacervates were examined using laser diffraction technique and optical microscopy along with Scanning Electron Microscopy, Fourier Transform Infrared analysis and Differential Scanning Calorimetry. Although both G:GA systems exhibited a similar behavior, some differences were observed. More specifically, results revealed that GA14 affected the surface charge characteristics of the G-GA complexes to a greater extent than GA7, while the corresponding liquid coacervates were more spherical, with a smoother surface and not aggregated. Additionally, G-GA14 complex coacervates were characterized by a more uniform morphology and size distribution along with a higher thermal stability implying thus a greater effectiveness of this system for the encapsulation of heat-sensitive materials.

Effects of natural copigment sources in combination with sweeteners on the stability of anthocyanins in sour cherry nectars

Effects of various co-pigment sources [gallic acid (GA), rose leaf extract (RLE), cherry stem extract (CSE), pomegranate rind extract (PRE) and green tea extract (GTE)] on anthocyanin content, colour, and turbidity in sour cherry nectar (SCN), sweetened with sucrose (SCNS), maltose syrup (SCNM) or honey (SCNH), were investigated during storage at 20 °C. Co-pigment sources were associated with increases in λmax (up to 4.1 nm), colour density (up to 22%), and polymeric colour (up to 1.7 times). Among the co-pigment sources, GA and PRE were associated with the greater anthocyanin stabilities in SCNS and SCNH. Moreover, the lowest turbidity, at the beginning of storage, and turbidity formation rate, throughout storage, were observed in SCNS, SCNM and SCNH containing PRE. When the changes in Amax, λmax, polymeric colour, colour density, and turbidity were considered together, PRE was the best co-pigment source, regardless of the sweetener used.