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•Complex coacervation between WPI-KC using a US pretreatment was achieved.•Despite WPI structure change by US treatment, coacervation with carrageenan remains.•Functional properties ...improvement was observed in US pretreated complex coacervates.
The aim of this work was to evaluate the influence of high-intensity ultrasound (HIUS) treatment on whey protein isolate (WPI) molecular structure as a previous step for complex coacervation (CC) with kappa-carrageenan (KC) and its influence on CC functional properties. Protein suspension of WPI (1% w/w) was treated with an ultrasound probe (24 kHz, 2 and 4 min, at 50 and 100% amplitude), non HIUS pretreated WPI was used as a control. Coacervation was achieved by mixing WPI and KC dispersions (10 min). Time and amplitude of the sonication treatment had a direct effect on the molecular structure of the protein, FTIR-ATR analysis detected changes on pretreated WPI secondary structure (1600–1700 cm−1) after sonication. CC electrostatic interactions were detected between WPI positive regions, KC sulfate group (1200–1260 cm−1), and the anhydrous oxygen of the 3,6 anhydro-D-galactose (940–1066 cm−1) with a partial negative charge. After ultrasound treatment, a progressive decrease in WPI particle size (nm) was detected. Rheology results showed pseudoplastic behavior for both, KC and CC, with a significant change on the viscosity level. Further, volume increment, stability, and expansion percentages of CC foams were improved using WPI sonicated. Besides, HIUS treatment had a positive effect on the emulsifying properties of the CC, increasing the time emulsion stability percentage. HIUS proved to be an efficient tool to improve functional properties in WPI-KC CC.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Ultrasonic oil bleaching reduces processing time, temperature and bleaching clay use.•Ultrasound oil bleaching showed no modifications in cis fatty acid configuration.•Spectroscopic ...tests on ultrasound-treated samples showed no evidence of oxidation.•Ultrasound-bleaching treatments generated yellow color in canola oil samples.
Canola seeds (Brassica napus L.) are among the most commonly used seeds in Mexico for vegetable oil production. This is based on the high yield and content of polyunsaturated and monounsaturated fatty acids. During oil bleaching, it is important to maintain fatty acids in their cis configuration because of the health concerns associated with trans-fatty acid consumption. In this sense, the industrial processing parameters employed for this purpose present some limitations, such as high temperatures and long times, which may change the cis configuration to trans. In addition, the amount of bleaching clay employed for this process could be a source of contamination because it is disposed of after treatment. Therefore, the aim of this study was to develop a bleaching process for canola oil using high-power ultrasound (US). US processing was applied to nine treatments with different processing times (60, 75, and 90 min), clay percentages (1, 2, and 3%), and temperatures (60 and 80 °C) to determine the concentrations of chlorophyll a and b (µg chlo/100 g oil), carotenes (µg β-carotene/100 g oil), color (L*, a*, b*, C*, and h°), iodine value (g I2/100 g oil), and finally carrying out a spectroscopic analysis (ATR-FTIR and Raman). A conventional bleaching treatment (100 °C for 180 min, 3% bleaching clay) was used as a control. The results revealed that US treatments with 2% clay at 60 °C for 60 and 90 min eliminated most of the chlorophyll compounds (98%). However, in terms of carotenes reduction, these identical treatments exhibited a similar tendency to that of the control (approximately 30% decrease). These findings also affected the sample color, in which US treatments revealed chromatic coordinates that indicated yellow tones with chroma values that were more intense than those in the control samples. In terms of the iodine value, such treatments fulfilled the international standards for vegetable oils (90–100 g I2/100 g oil). Finally, the spectroscopic study revealed no trans configurations or the presence of different chemical compounds after US treatment, because neither of them presented typical peaks for those molecular configurations. In this regard, US can be a useful methodology for bleaching vegetable oils, helping to reduce time, and bleaching clay with similar pigment reduction results.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this study, both microbial inactivation and growth of Listeria spp. inoculated in commercial free-starter fresh cheese was evaluated after high-pressure processing (HPP). HPP conditions (300, 400, ...500 and 600 MPa at 6 °C for 5 min) and inoculum level (3–4 or 6–7 log CFU/g of cheese), as well as differences among strains inoculated (Listeria innocua, L. monocytogenes CECT 4031 and L. monocytogenes Scott A) were investigated. Inactivation and generation of sublethal injury were determined after HPP using ALOA (Agar Listeria according to Ottaviani and Agosti) and TAL (Thin Agar Layer) plating methods, respectively. Listeria inactivation increased with the pressure applied, presenting some statistical differences between the employed strains, inoculum level and sublethal injury. The highest lethality values were obtained at 600 MPa for the three strains tested, although the 500 MPa treatment presented high lethality for L. innocua and L. monocytogenes CECT 4031. After treatment, L. innocua and L. monocytogenes CECT 4031 counts in fresh cheese increased gradually during cold storage. By contrast, counts in cheeses inoculated with L. monocytogenes Scott A did not change significantly (p ≥ 0.05), being this strain the most pressure resistant and with the slowest growth rate. The manuscript present information supporting that, strains with high-level resistance should be employed during inactivation studies, instead of surrogate microorganisms. Application of HPP treatments of 500 MPa and especially 600 MPa on fresh cheeses would be effective to eliminate the most resistant microorganism to a level that should not present a public health risk under normal conditions of distribution and storage.
•After test, the highest Listeria inactivation was obtained in 600 MPa at 6°C- 5 min.•Among the evaluated strains, L. monocytogenes Scott A was the most baroresistant.•For the inactivation achieved, inoculation level and strain had significant effect.•During storage at 4 °C, 600 MPa treated samples presented the slowest recovery rate.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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•WPC-milk blends were thermosonicated (TS) (24 kHz, 400 W; 2, 4, 6 min; 50, 55, 60 °C).•Selected TS-treated blends were proposed to make reduced fat cheeses (RFCs).•Optimized TS ...conditions (%fat, T, TS time) allowed preparing LFCs.•LFCs made with TS blends showed similar texture profiles than full-fat cheeses.•High moisture, high protein LFCs were made with very short TS treatments.
Aiming at producing a reduced fat cheese (RFC) as an alternative to full-fat Panela cheese, a highly consumed fresh Mexican dairy product, thermosonication (TS) processes (24 kHz, 400 W nominal power, 2, 4 and 6 min; 50, 55 and 60 °C) were evaluated to treat WPC (80% protein) blended with reduced-fat milk (1 and 2% fat), which were later LTLT pasteurized. TS blends were compared in terms of their technological properties (water holding capacity-WPC, gel firmness- GF, color, pH and titratable acidity) with those of a regular full fat (3%) LTLT pasteurized milk used as a control. Afterwards, a regression analysis was carried out with the obtained data in order to select the most appropriate conditions for cheesemaking purposes (similar GF, higher WHC with respect to the control), minimize both fat content and TS treatment duration to minimize energy expenses. According to these restrictions, the selected conditions were 1.5% fat milk-WPC blend, TS treated at 60 °C for 120 s; 1% fat milk-WPC blend, TS treated at 50 °C for 120 s and 1% fat milk-WPC blend, 50 °C for 144 s, which allowed preparing low fat cheeses (LFCs). These TS treatments were applied in a larger scale to elaborate Panela-type LFCs comparing different technological properties (cheese yield, syneresis, water content, texture profile analysis, color and titratable acidity) with those of a full fat variety, at day 1 and during 14 days of refrigerated storage. Results showed similar texture profiles of LFC cheeses and full fat milk cheeses throughout their storage period with significant changes in composition parameters (higher moisture, protein and salt contents, with low fat percentages), syneresis, selected color parameters (hue, b*), with no observed changes in cheese yield, TA and pH during cheese storage. These promising results are encouraging to develop LFCs with no physicochemical or technological defects using novel processing techniques that may help reducing calorie consumption without compromising sensory acceptability.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Aim
The present investigation was aimed at isolating and identifying bacterial strains from cured vanilla beans. Additionally, the study focused on evaluating bacterial processes pertaining to the ...aromatic compounds production (ACP).
Methods and Results
Three bacteria were isolated from Vanilla planifolia beans, previously subjected to the curing process. According to morphological, biochemical and 16S rRNA analysis, the strains were identified as Citrobacter sp., Enterobacter sp. and Pseudomonas sp. The polygalacturonase activity (PGA) was determined using the drop, cup‐plate and DNS methods. Aromatic compounds production was analysed by cup‐plate method using FA as substrate and quantified by high performance liquid chromatography (ppm), the functional groups of vanillic acid (VA) were identified by FT‐IR and the aromatic compounds (AC) resistance was determined and reported as minimum inhibitory concentration. Citrobacter sp., Enterobacter sp. and Pseudomonas showed PGA (70·31 ± 364, 76·07 ± 12·47 and 51 ± 10·92 U ml−1 respectively), were producers of VA (3·23 ± 0·49, 324 ± 41 and 265·99 ± 11·61 ppm respectively) and were resistant to AC.
Conclusions
The Gram‐negative bacteria isolated from V. planifolia beans were responsible for ACP.
Significance and Impact of the Study
This is the first evidence for the role of Gram‐negative bacterial isolates from cured Mexican V. planifolia beans in the process related to ACP.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The effect of ultra-high-pressure homogenization (UHPH) on raw whole milk (3.5% fat) was evaluated to obtain processing conditions for the sterilization of milk. Ultra-high-pressure homogenization ...treatments of 200 and 300MPa at inlet temperatures (Ti) of 55, 65, 75, and 85°C were compared with a UHT treatment (138°C for 4s) in terms of microbial inactivation, particle size and microstructure, viscosity, color, buffering capacity, ethanol stability, propensity to proteolysis, and sensory evaluation. The UHPH-treated milks presented a high level of microbial reduction, under the detection limit, for treatments at 300MPa with Ti of 55, 65, 75, and 85°C, and at 200MPa with Ti=85°C, and few survivors in milks treated at 200MPa with Ti of 55, 65, and 75°C. Furthermore, UHPH treatments performed at 300MPa with Ti=75 and 85°C produced sterile milk after sample incubation (30 and 45°C), obtaining similar or better characteristics than UHT milk in color, particle size, viscosity, buffer capacity, ethanol stability, propensity to protein hydrolysis, and lower scores in sensory evaluation for cooked flavor.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The occurrence of aflatoxin M1 (AFM1) in infant formulae commercialized in the metropolitan area of Monterrey (Nuevo León, Mexico) was determined by using immunoaffinity column clean-up followed by ...HPLC determination with fluorimetric detection. For this, 55 infant formula powders were classified in two groups, starter (49 samples) and follow-on (6 samples) formulae. Eleven of the evaluated samples (20%) presented values above the permissible limit set by the European Union for infant formulae (25 ng/L), ranging from 40 to 450 ng/L. The estimated daily intake (EDI) for AFM1 was determined employing the average body weight (bw) of the groups of age in the ranges of 0–6 and 6–12 months, and 1–2 years. The results evidenced high intake values, ranging from 1.56 to 14 ng/kg bw/day, depending on the group. Finally, with the EDI value, the carcinogenic risk index was determined, presenting a high risk for all the evaluated groups. Based on these results, it is a necessary extra effort by the regulatory agencies to reduce the AFM1 presence in infant formulae consumed in Mexico.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Multiple‐pass ultrahigh pressure homogenization (UHPH) was used for reducing microbial population of both indigenous spoilage microflora in whole raw milk and a baroresistant pathogen (Staphylococcus ...aureus) inoculated in whole sterile milk to define pasteurization‐like processing conditions. Response surface methodology was followed and multiple response optimization of UHPH operating pressure (OP) (100, 175, 250 MPa) and number of passes (N) (1–5) was conducted through overlaid contour plot analysis. Increasing OP and N had a significant effect (P < 0·05) on microbial reduction of both spoilage microflora and Staph. aureus in milk. Optimized UHPH processes (five 202‐MPa passes; four 232‐MPa passes) defined a region where a 5‐log10 reduction of total bacterial count of milk and a baroresistant pathogen are attainable, as a requisite parameter for establishing an alternative method of pasteurization. Multiple‐pass UHPH optimized conditions might help in producing safe milk without the detrimental effects associated with thermal pasteurization.
Significance and Impact of the Study: Milk is usually heat‐preserved, but certain thermal‐related modifications in nutritional, sensory and functional properties may arise. Consequently, nonthermal technologies such as ultrahigh pressure homogenization (UHPH) are currently explored. As part of the scientific criteria needed to assess UHPH equivalency to thermal pasteurization, microbial reduction of both the most baroresistant pathogen and native milk microflora must be determined and processing conditions could be defined through multiple response optimization. Results from the present study show that optimized multiple‐pass UHPH treatments are capable of a 5‐D reduction of both spoilage and pathogenic flora in whole milk.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Physicochemical and sensory properties of Adobera, a genuine, understudied Mexican raw‐milk cheese, were explored by analysing commercial samples from different manufacturers and seasons. ...Composition‐wise, Adobera could be considered a fresh cheese with a high moisture content (42.5%), although its relatively low water activity (0.953) and pH (5.14) and high free amino acid content (0.46 mmol/g, dry basis) could indicate otherwise. Instrumental texture corresponded to that of a semifirm cheese, while its colour was whitish‐to‐ivory. Both texture and composition were significantly affected by sampling season and cheese composition, while some attributes of sensory acceptability significantly varied with brand.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
The Ultra High-Pressure Homogenization (UHPH) process has proved to be an adequate technology to produce milk with similar microbial, sensory and physicochemical characteristics to the heat-treated ...milk. However, no information has been published regarding the effect of this technology on the vitamin content of milk. For this reason, the aim of this work was to evaluate the effect of the UHPH process on milk vitamins, comparing the results with those obtained by applying heat treatments. The UHPH conditions evaluated were those in which the microbial and physicochemical characteristics obtained in milk were similar to the characteristics of pasteurized (PA) and UHT milks, consisting these treatments in the application of 300MPa at different inlet temperatures (Ti) of 45, 55, 65, 75 and 85°C; the heat treatments applied were 90°C for 15s and 138°C for 4s in PA and UHT milks, respectively. The hydrosoluble vitamins analyzed were nicotinamide, thiamine, pyridoxal, pyridoxamine, folic acid, cyanocobalamin, riboflavin and vitamin C (total vitamin C), and retinol and α-tocopherol in the liposoluble vitamin group. The results showed an important reduction in the destruction of nicotinamide, thiamine, riboflavin and vitamin C in the UHPH-treated milks compared to those heat-treated. Further, the UHPH treatments tested were able to retain most of the vitamin content presented in raw milk. In this sense, the sample treated at 300MPa with Ti=45°C presented the closest vitamin content to that of raw fresh milk. In addition, the increase of the Ti in the UHPH treatments applied produced a significant increment (P<0.05) on the vitamin destruction, especially in nicotinamide, thiamine, riboflavin and vitamin C in milk, with a maximum of destruction of 19.97, 33.46, 13.46 and 22.56%, respectively at 300MPa with Ti=85°C. On the contrary, an important destruction of nicotinamide, thiamine, riboflavin and vitamin C (27.31, 33.46, 17.30 and 61.28%, respectively) was observed in the UHT milk. Additionally, the content of liposoluble vitamins in milk was almost not affected by both heat and UHPH treatments applied. These results show the possibility of employing the UHPH technology in milk to reduce the vitamin destruction, obtaining a milk with higher nutritional properties than a heat-treated milk.
•UHPH treatments applied increase milk vitamin retention compared to the heat-treated milk.•Milk treated by UHPH at 300MPa and Ti=45°C presented a vitamin content close to that of raw milk.•Hydrosoluble vitamin content in milk UHPH-treated at 300MPa with Ti=85°C was higher than heat-treated milks.•UHPH treatments applied did not affect the retinol and α-tocopherol content in milk.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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