Effects of moisture content on structural and dielectric properties of cassava starch films

In this work, it was evaluated the effect of moisture content on the structural and dielectric properties of cassava starch films by means of Fourier Transform infrared spectroscopy (FTIR), impedancimetric, and gravimetric analysis. The film samples were equilibrated in hermetically sealed desiccators, containing different saturated salts in water in order to promote activity of water between 0.11 and 0.85. The position and amplitude of the peaks in the fingerprint region of the FTIR spectra were changed due to the modifications in the interactions between the polymeric chains and water molecules. These effects may be related to the formation of semi-crystalline regions in the film structure. The dielectric properties of the films were also strongly dependent on the moisture content, showing a non-linear and a linear region, which was attributed to the domain of bound and free water in the film, respectively. The gravimetric analyzes showed the typical sigmoidal behavior, attributed to the way the water interacts with the biopolymer. Finally, the flexibility of the films increased with water content increasing.FAPESPFAPESP [05/54688-7

Phase transitions of frozen Camu-camu (Myrciaria dubia (H.B.K.) McVaugh) pulp: effect of cryostabilizer addition

Camu-camu is a tropical fruit with very high vitamin C content and commercialized as frozen pulp. Enthalpies of freezing, temperatures of the onset of ice melting, and glass transition temperatures of the maximally freeze-concentrated phase (T′g) of camu-camu pulp and of samples containing maltodextrin (DE20) and sucrose were measured by differential scanning calorimetry. Maltodextrin exhibited the largest freeze stabilization potential, increasing T′g from −58.2 °C (natural pulp) to −39.6 °C when 30% (w/w) maltodextrin DE 20 was added. Sucrose showed negligible effect on T′g but enhanced considerably the freezing point depression and less amount of ice was formed33312317sem informaçãosem informaçãoThe authors gratefully acknowledge the financial support from FAEPEX–UNICAM

Assessment of the suitability of pitanga leaf extract as a natural antioxidant for enhancing canola oil stability : monitoring lipid oxidation parameters

The efficiency of pitanga leaf extracts (PLE) to protecting vegetable oils against lipid oxidation is evaluated and compared with the synthetic antioxidant butylated hydroxytoluene (BHT). In addition, the main phenolic compounds and antioxidant properties of PLE are determined by UPLC-DAD-MS/MS and spectrophotometric methods. Moreover, the fatty acid composition and lipid oxidation of canola oil containing five different concentrations of PLE (200-1000ppm), BHT or without added antioxidant are evaluated after being subjected to accelerated oxidation conditions (60 degrees C during 16 days). The results show a considerable amount of phenols (229.4mg gallic acid/g extract) with two major phenolic compounds (miricitrin and quercetin 3-alpha-fucopiranoside) in the PLE intermediate fraction. The fatty acid composition of canola oils with additives did not change significantly after 16 day of accelerated oxidation (7.3% SFA, 64.5% MUFA, and 27.8% PUFA). The incorporation of PLE, even at the minimum concentration assayed (200ppm), offers important decreases of primary and secondary oxidation products with respect to the control sample, obtaining reduction percentages of 74, 58, 62, and 61% for peroxides, conjugated dienes, p-anisidine, and TBARS values, respectively. A similar stability for canola oil is observed with BHT at equivalent concentrations, enhancing the inhibitory effects against lipid oxidation in different oxidations steps. The incorporation of pitanga leaf extracts to canola oils is a promising strategy to preserve their polyunsaturated fatty acids, avoiding their lipid oxidation during storage. This procedure is of great interest due to the natural origin of the additive under study versus synthetic antioxidants like butylated hydroxytoluene. The antioxidant potential of pitanga leaf extracts, including UPLC-DAD-MS/MS phenolic profile, antioxidant activities, and their effects on canola oil stability after accelerated storage conditions, are evaluated1215CNPQ - Conselho Nacional de Desenvolvimento Científico e TecnológicoFAPESP – Fundação de Amparo à Pesquisa Do Estado De São Paulo43.4089/2016-8; 30.3180/2013-6; 32402742902013/07914-

Influence of pitanga leaf extracts on lipid and protein oxidation of pork burger during shelf-life

The effect of pitanga leaf extracts, as source of natural antioxidants, on physicochemical properties as well as lipid and protein oxidation of pork burgers during storage at 2 ± 1 °C, packed under modified atmosphere, was assessed. Formerly, the in vitro antioxidant and antimicrobial activities as well as the phenolic profile of pitanga leaf extracts were also studied. Thereafter, five samples were prepared, including control (without antioxidants), commercial synthetic antioxidant (BHT at 200 mg/kg) and three concentrations of pitanga leaf extracts: PLL (at 250 mg/kg), PLM (at 500 mg/kg) and PLH (at 1000 mg/kg). The predominant phenolic compounds identified in pitanga leaf extracts were hydroxycinnamic acids, followed by tyrosol and other phenolics (alkylmethoxyphenols, hydroxycoumarins and hydroxyphenylpropenes). Pitanga leaf extracts showed a high antioxidant and antimicrobial in vitro activity. The addition of pitanga leaf extracts improved the redness of pork burgers during the whole display. On the other hand, the addition of natural antioxidants decreased the lipid oxidation from day 7 till the end of storage period. Burgers with antioxidant showed a similar protein oxidation level, observing an inhibition between 36% and 49% compared to control treatment. From the results, it can be concluded that pitanga leaf extract is a good alternative to commercial synthetic antioxidants to improve the quality and extend the shelf-life of pork burgers1144754CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP43.4089/2016-8; #302763/2014-7; #305804/2017-033003017027P12013/07914-

Guarana seed extracts as a useful strategy to extend the shelf life of pork patties: UHPLC-ESI/QTOF phenolic profile and impact on microbial inactivation, lipid and protein oxidation and antioxidant capacity

The antioxidant and antimicrobial effects of guarana seed extracts (GSE) added to pork patties were evaluated for 18 days storage at 2 ± 1 °C. Five treatments were prepared: i) without natural antioxidant [control (negative control)], ii) with BHT at 200 mg/kg (positive control), and iii) with three different concentrations: 250  mg/kg (guarana seed low dose-GSL), 500  mg/kg (guarana seed medium dose-GSM) and 1000  mg/kg (guarana seed high dose-GSH) of guarana extracts, respectively. The pH, instrumental colour (CIE L*, a*, b*), total viable counts (TVC), Pseudomonas spp. counts and lactic acid bacteria (LAB) counts, 2-thiobarbituric acid reactive substances (TBARS) and carbonyl content were determined after 0, 7, 11, 15 and 18 days of storage period. The in vitro antioxidant activity together with the phenolic profile of GSE was also studied. Microbial analysis showed that GSE had no antimicrobial activity on pork patties. The untargeted UHPLC-ESI-QTOF approach confirmed the wide phenolic composition of GSE able to explain the antioxidant power (28.2 g/kg of phenolic equivalents). Low doses (GSL) of GSE were able to preserve the values of colour parameters, obtaining higher L*, a* and b* values during storage, which is reflected in the lowest colour differences during storage (ΔE*0–18 = 4.56). TBARS and carbonyls values in GSE added samples were lower than control and BHT ones. GSL and GSM provided better results than the synthetic antioxidant (0.08 and 0.07 vs 0.18 mg MDA/kg; 2.47 and 3.13 vs 3.23 nmol/mg, for GSL and GSM vs BHT, respectively). These findings show that GSE are very effective against colour deterioration, lipid and protein oxidation in pork patties and possessing the potential to be used as natural antioxidants. [Display omitted] •Guarana seed extracts contain powerful phenolic antioxidants to be used in the meat industry.•Guarana seed extract enhances the colour of pork patties.•Guarana seed extract shows great effectiveness to protect meat against oxidation.•Guarana extract does not have antimicrobial activity in pork patties

Influence of pitanga leaf extracts on lipid and protein oxidation of pork burger during shelf-life

The effect of pitanga leaf extracts, as source of natural antioxidants, on physicochemical properties as well as lipid and protein oxidation of pork burgers during storage at 2 ± 1 °C, packed under modified atmosphere, was assessed. Formerly, the in vitro antioxidant and antimicrobial activities as well as the phenolic profile of pitanga leaf extracts were also studied. Thereafter, five samples were prepared, including control (without antioxidants), commercial synthetic antioxidant (BHT at 200 mg/kg) and three concentrations of pitanga leaf extracts: PLL (at 250 mg/kg), PLM (at 500 mg/kg) and PLH (at 1000 mg/kg). The predominant phenolic compounds identified in pitanga leaf extracts were hydroxycinnamic acids, followed by tyrosol and other phenolics (alkylmethoxyphenols, hydroxycoumarins and hydroxyphenylpropenes). Pitanga leaf extracts showed a high antioxidant and antimicrobial in vitro activity. The addition of pitanga leaf extracts improved the redness of pork burgers during the whole display. On the other hand, the addition of natural antioxidants decreased the lipid oxidation from day 7 till the end of storage period. Burgers with antioxidant showed a similar protein oxidation level, observing an inhibition between 36% and 49% compared to control treatment. From the results, it can be concluded that pitanga leaf extract is a good alternative to commercial synthetic antioxidants to improve the quality and extend the shelf-life of pork burgers. [Display omitted] •Pitanga leaf extract is a good alternative to commercial antioxidant to extend the shelf-life of burgers•The main phenolics measured in pitanga leaf extract were hydroxycinnamics and tyrosols•The addition of pitanga leaf extracts improved the redness of pork burgers during the whole display•Pitanga leaf extract decreased the lipid and protein oxidation of pork burger