Hayette Louaileche

Effect of storage time and temperature on the physicochemical and sensory characteristics of commercial apricot jam

Storage conditions are important factors for jam quality. The objective of this study was to monitor the physicochemical stability and sensorial profile of apricot jam during storage for 60 days at 5 °C, 25 °C and 37 °C. For that purpose, special attention was paid to total soluble solids (TSS), titratable acidity (TA), colour, free amino acids (FAA), total sugars (TS) and hydroxymethylfurfural (HMF). The decreasing parameter for jam at the end of storage under 5 °C, 25 °C and 37 °C, respectively, were 16.81%, 34.30% and 56.01% for FAA, and 5.52%, 9.02% and 7.46% for TS; likewise, the increasing were 19.81%, 22.94% and 25.07% for TA, 3.15%, 4.08% and 4.47% for TSS, 15.96%, 112.76% and 150% for HMF. Jam stability was better at 5 °C than 25 °C and 37 °C. The interaction time-temperature factor had significant effects on pH, TS, FAA and HMF, unlike TA, TSS and sensorial profile.

Betalain profile, phenolic content, and color characterization of different parts and varieties of Opuntia ficus-indica.

Three different varieties of Opuntia ficus-indica (R, red; Y, yellow; RY, red-yellow) have been considered in this study. Attention was focused on differential tristimulus colorimetry and on the analysis of individual betalains (HPLC-DAD-ESI-ToF-MS) and phenolic content, scarcely previously reported in these kinds of samples. The importance of this research stems from the elucidation of the parts and varieties of cactus pear more optimal for use as natural colorants and sources of phenolics and betalains. Thus, the RY pulp was appropriate to obtain colorants with high color intensity (C*(ab) = 66.5), whereas the whole Y fruit and R pulp reached powerful and stable yellow and red colors, respectively (C*(ab)/h(ab), 57.1/84.7 and 61.1°/81.8°). This choice was also based on the visually appreciable differences (ΔE*(ab) > 5) among samples, mainly quantitative (%Δ(2)L, %Δ(2)C). In addition, seeds of all Opuntia varieties showed significantly (p < 0.05) similar phenolic content (around 23.3 mg/g) and color characteristics.

Deployment of response surface methodology to optimize recovery of dark fresh fig (Ficus carica L., var. Azenjar) total phenolic compounds and antioxidant activity.

Optimum conditions for extracting total phenolic compounds (TPC) and antioxidant activity from fresh dark fig (Ficus carica L.) have been investigated using response surface methodology (RSM). The Box-Behnken design was used to investigate the effects of three independent variables, acetone concentration (40-80%), temperature (25-65 °C), and time (60-120 min), on the response. Regression analysis showed that about 96% of the variation was explained by the models. P-value for the lack of fit was insignificant which confirmed the validity of models. Response surface analysis showed that the optimal extraction parameters that maximized antioxidants extraction were 63.48% acetone, 115.14 min, and 48.66 °C. Under optimum conditions the corresponding experimental values for TPC and antioxidant activity were 536.43 and 71.86 mg GAE/100 g DM. The experimental values are in accordance with those predicted, indicating the suitability of the model and the success of RSM in optimizing the extraction conditions.

Ortho-diphenol profile and antioxidant activity of Algerian black olive cultivars: effect of dry salting process.

Six Algerian olive cultivars (Azeradj, Sigoise, Bouchouk, Abelout, Aberkane and Atefah) processed by dry salting were investigated for the total polyphenols, ortho-diphenol profile and antioxidant activity. The dry salting affects total polyphenol and o-diphenol contents with a loss rate of 6-46% and 7-50%, respectively, depending on the cultivar. Consequently, a decrease in the antioxidant activity was observed, 10-35% for the reducing power, 29-58% for the DPPH radical scavenging activity and 10-48% for the ferrous-chelating power. Among the o-diphenols identified in the salted olives, hydroxytyrosol was the most abundant followed by verbascoside and caffeic acid. The comparative study showed that Sigoise from Relizane which contains the highest levels of polyphenols and o-diphenols exhibits the best antioxidant activity. Our results suggest that in addition to the processing, the cultivar and the geographical origin would have a pronounced influence on both o-diphenol composition and antioxidant activity of olives.

Optimization of phenolic compound recovery and antioxidant activity of light and dark dried fig ( Ficus carica L.) varieties

The optimum conditions for extraction of total phenolic contents (TPC) and for enhancing the antioxidant activity from light and dark dried figs were determined. The effects of the solvent nature (acetone, ethanol, methanol, or water), solvent concentration (20–80%), acetic acid concentration (0–2%), extraction temperature (25–70°C), extraction time (0.5–4 h), sample to solvent ratio (1/25–1/100), and number of extractions (1, 2, and 3) were determined. The TPC was used to identify antioxidant compounds. 2,2-diphenyl-1-picrylhydrazyl (DPPH) was used to evaluate antioxidant activity. All extraction parameters had significant effects (p<0.05) on the TPC and the antioxidant activities. The best conditions were obtained with double extraction using 60% acetone without acidification, at 40°C for 120 min, and with a 1/75 solid to solvent ratio. These conditions resulted in TPC concentrations of 469.46 (light variety) and 399.79 mg of gallic acid (GAE)/100 g (dark variety), and antioxidant activities of 96.47 and 102.28 mg of GAE/100 g, respectively.

Extraction of phenolic compounds and in vitro antioxidant capacity of prickly pear seeds

Abstract The extraction of phenolic compounds from prickly pear seeds was studied. Extraction experiments were carried out by investigating the effect of solvent nature (acetone, ethanol, methanol and water), solvent concentration (25–100%), sample to solvent ratio (0.2/10 to 0.8/10 g/ml), extraction time (30–150 min), and temperature (25–90°C) on the recovery of phenolic compounds and antioxidant activity of the extracts. Total phenolic content was assessed to determine the antioxidant compounds while ferric-reducing power and free radical scavenging activity were used to evaluate the antioxidant activity of prickly pear seed extracts. Experimental results showed that all extraction parameters had significant effects (p < 0.05) on total phenolic content and antioxidant activities of the extracts. The best conditions were: 75% acetone, 0.2 g/10 ml, 90 min, and 90°C with values of 416 mg gallic acid equivalents/100 g for total phenolic content, 237 mg ascorbic acid equivalents/100 g for ferric-reducing power, and 95% for free radical scavenging activity. Ferric-reducing and free radical scavenging potentials were found to be positively significantly correlated with phenolic content under the influence of all extraction parameters.

Carbon dioxide fixation by cells and cell-free extracts of Streptococcus thermophilus

The present study describes fixation into cellular amino acids of 14 C from NaH 14 CO 3 by growing cells and cell-free extracts of Str. thermophilus, and the enzyme system responsible for fixation. In addition, a comparison was made of the bicarbonate uptake and carboxylase activity of two morphological variants.

Effects of extraction conditions on the recovery of phenolic compounds and in vitro antioxidant activity of carob (Ceratonia siliqua L.) pulp

Abstract The extraction of phenolic compounds from carob pulp was studied. The effects of solvent nature (acetone, ethanol, methanol and water), solvent concentration (40–100%), solid-to-solvent ratio (15/10 to 75/10 mg/ml), extraction time (60–120 min) and extraction temperature (25–90°C) were investigated. Total phenolic content and total flavonoid content were used for determination of phenolic compounds of carob pulp extract, whereas the antioxidant activity was assessed by measuring the free radical-scavenging activity and the ferric-reducing power. Experimental results showed that all examined parameters had statistically significant (p < 0.05) effects on phenolic compound extraction and antioxidant activities of extracts. The best extraction conditions were 70% acetone, 25 mg/10 ml, 90 min and 90°C with values of 3554 mgGAE/100 gDW, 1700 mgQE/100 gDW, 4032 mgAAE/100 gDW and 3929 mgAAE/100 gDW for the total phenolic content, the total flavonoid content, the free radical-scavenging activity and the ferric-reducing power, respectively. As a function of investigated extraction parameters, phenolic compound contents were positively correlated with antioxidant activities.