Effects of Thermal and High-pressure Treatments on the Microbiological,Nutritional and Sensory Quality of a Multi-fruit Smoothie

Fruit juices have become an important product for the healthy food world. In the last 5 years, the sales of industrial juices treated by non-thermal preservation technologies such as high-pressure processing (HPP) have strongly increased. In the present study, the effect of the application of two stabilization treatments, mild heating (MH; 80 °C for 7 min) and high-pressure processing (HPP; 350 MPa for 5 min), on multi-fruit smoothies was compared on a wide range of quality parameters immediately after treatment and during a refrigerated storage of 21 days. From the physico-chemical and instrumental colour point of view, immediately after treatment, HPP smoothies were more similar to the fresh product than those treated by MH. During storage, the colour of MH smoothies was more stable although HPP ones showed lower browning index and viscosity more similar to the untreated product. Additionally, HPP provided smoothies with better sensory properties and higher nutritional quality than MH. In general, HPP smoothies were more similar to the untreated product. However, HPP smoothies kept a residual enzyme activity which is likely to limit the shelf life of this multi-fruit smoothie.     

Effects of processing and packaging on vitamin C and β-carotene content of ready-to-use (RTU) vegetables

High pressure liquid chromatographic methods were used for measurement of the concentration of vitamin C and β-carotene in broccoli and green pepper. The effects of processing, packaging and storage on the levels of these nutrients in both unprocessed and processed ready-to-use (RTU) vegetables were determined. Systems investigated included: (a) unpacked and pillow packaged broccoli, and (b) unpacked, pillow, partial vacuum, and total vacuum packaged green pepper. There was a statistically significant decrease in vitamin C over a 10 day storage period of unpacked and packaged vegetables including all four packaging systems (P<0.001, overall average decrease of 11%). The overall loss of β-carotene during the 10 day storage period was not statistically significant (P=0.14). Although there was a significant loss in vitamin C during storage, in most cases there was no difference in loss of vitamin C or β-carotene between the processed and unprocessed vegetables, and the packaging systems.     

Physiological and biochemical changes of different fresh-cut mango cultivars stored at 5 °C

Treatments to inhibit browning, decay and to extend shelf life of ‘Keitt’, ‘Kent’ and ‘Ataulfo’ mango cultivars as a fresh‐cut produce were investigated. Combinations of calcium chloride (CaCl₂), antioxidants [ascorbic acid (AA), citric acid (CA)] and two commercial film coatings resulted in a reduction of browning and deterioration of fresh‐cut mangoes stored at 5 °C, especially for the Ataulfo cultivar. The use of CaCl₂ + AA + CA significantly reduced colour deterioration, loss of firmness and did not affect sensory characteristics of fresh‐cut mango, with a larger effect in the Ataulfo cultivar. In general, these treatments prevented loss of sugar and vitamin C of cubes during storage at 5 °C. Shelf life of this cultivar was 21 days, while that of Keitt and Kent was only 9 and 12 days, respectively. There is a correlation between carotene and vitamin C content of Ataulfo mango and its longer shelf life compared with the other cultivars.     

Effect of high‐pressure processing on immunoreactivity,microbial and physicochemical properties of hazelnut milk

This study investigated the effects of high‐pressure processing (HPP) and thermal processing (TP) on the overall quality attributes of hazelnut milk. HPP achieved the same microbial safety as TP, and the pH, °Brix and sugar contents were maintained at the levels of fresh hazelnut milk. Although HPP caused colour changes, the ?E was smaller than that of the TP sample. Increasing pressure significantly decreased the immunoreactivity of the hazelnut milk by 70%, while simultaneously reducing the levels of essential and non‐essential amino acids and chemical score (CS) and the essential amino acid index (EAAI) values. However, neither HPP nor TP significantly affected the fatty acid composition of hazelnut milk. HPP retained higher total phenolic and flavonoid levels of the hazelnut milk, with a better antioxidant capacity than TP samples. Thus, the HPP maintained microbial safety during cold storage, and physicochemical properties of the treated hazelnut milk were not significantly different from those of the fresh hazelnut milk.     

Postharvest Ripening Characterization of Greenhouse Tomatoes

The determination of °Brix, pH, titratable acidity and antioxidant composition such as β-carotene, lycopene, and vitamin C was done in greenhouse “Savoura” tomatoes during maturation. The chromatic values L*, a*, b* were determined at the top surface of the tomato, and its strength-deformation curve was tested with a texturometer. Results pointed out that °Brix and titratable acidity did not change during postharvest, while β-carotene, lycopene, and vitamin C contents increased continuously toward the red stage of tomato. The colour values L*, a*, b*, and ratio a*/b* had a good correlation with the maturity stages. Also, a high correlation between lycopene content and (a*/b*) ratio was found, which was well represented with a second order polynomial function (r² = 0.95). This equation permits to appropriately estimate lycopene content of tomato as a function of its color, without any chemical analysis. During ripening, tomato texture changed from firm turgid to soft and the puncture deformation degree increased. Tomato firmness and chromatic values had a good correlation, and the lycopene content was a logarithm function of firmness (r² = 0.81). The strength in puncture test increased linearly with deformation until the bioyield point. The measured force was analyzed as the sum of the compression and the shear forces. The two force coefficients can be considered as tomato properties, independent of the puncture probe. These coefficients were found to decrease during tomato maturation.     

Mechanism of colour change of carambola puree by high pressure processing and its effect on flavour and physicochemical properties

The study aimed to investigate the mechanism of the colour change of carambola puree by high pressure processing (HPP), and the effects on its flavour, antioxidant properties and other physicochemical properties. The results showed that the colour change of carambola puree after HPP (200, 400, 600 and 800 MPa, for 15 min at 25 °C) was caused by both the enzymatic browning inhibition and the β-carotene release promotion. The physical and chemical properties also varied after HPP treatment, in which the potential of hydrogen (pH) value and the total soluble solids decreased with the pressure. With the increase of pressure, the content of total phenols and flavonoids increased to a certain extent, and the antioxidant activity also increased. HPP could destroy the cell structure and form microscopic pores in the tissue, which might cause changes in physical and chemical properties. Compared with untreated samples, HPP could improve the characteristic flavour and quality of the sample itself, and it has a great application prospect in the production of carambola puree.     

Thermal degradation kinetics of carotenoids,vitamin C and provitamin A in tree tomato juice

In this research, the influence of temperature on the degradation of carotenoids, vitamin C and provitamin A in tree tomato juice was studied at 70, 80 and 90 °C. The thermal processing significantly reduced (P < 0.001) the concentration of the bioactive compounds, and the thermal degradation in the evaluated phytochemicals fit a kinetic first order, with the following activation energies (Ea, kJ mol⁻¹): α-carotene (69.75), β-carotene (59.50), provitamin A (51.67), zeaxanthin (43.66), vitamin C (41.27), lycopene (18.84) and β-cryptoxanthin (18.23). The kinetic study and thermodynamic analysis of the tree tomato juice showed that the degree of thermoresistance in the phytonutrients responded in the following order: β-cryptoxanthin > lycopene > vitamin C > zeaxanthin > provitamin A > β-carotene > α-carotene. This study benefits engineering processes interested in the design and optimisation of thermal processes aimed at preserving the nutritional quality of tree tomato juice.     

In vitro bioaccessibility of isoflavones from a soymilk-based beverage as affected by thermal and non-thermal processing

High Pressure Processing (HPP) and High Intensity Pulsed Electric Fields (HIPEF) are non-thermal processing technologies used for obtaining safe and high-quality foods and beverages. In the present work, the changes on both the concentration and the bioaccessibility of isoflavones from treated (thermally and non-thermally) and untreated soymilk-based beverages were evaluated. Thermal treatment (TT) was applied at 90 °C for 1 min, HPP: 400 MPa at 40 °C for 5 min and HIPEF: 35 kV cm⁻¹ with 4 μs bipolar pulses at 200 Hz for 1800 μs. Later, beverages were subjected to an in vitro gastrointestinal digestion for obtaining the bioaccessibility. Thermal and non-thermal processing increased the isoflavone concentration up to 25–26% in TT and HIPEF treated beverages, and up to 38.52% in HPP treated. After in vitro digestion, the concentration of isoflavones in non-thermally processed beverages was higher (70.55% for HIPEF and 98.77% for HPP) than that TT processed (18.52%). HIPEF processing and HPP increased the isoflavone bioaccessibility up to 35.40 and 47.32%, respectively, regarding the untreated product. These results demonstrate that both non-thermal processing technologies HIPEF and HPP are suitable for obtaining high quality and nutritious beverages by improving their isoflavone bioaccessibility.     

Effect of high pressure processing on heat-induced gelling capacity of blue crab (Callinectes sapidus) meat

There has been increasing use of High pressure processing (HPP) in the fishery industry since this technology facilitates shellfish shucking. Nevertheless, there is limited information about the effect of HPP on protein functional properties of some shellfish. The aim of this study was to evaluate the effect of 100, 300 and 600 MPa/5 min on the gelling capacity of heat-induced (40 °C/30 min + 90 °C/20 min) blue crab (Callinectes sapidus) meat. HPP treatment resulted in crab meat gels with a lighter and reddish colour as compared to the control. HPP at 600 MPa induced the formation of high molecular aggregates from the denaturation-aggregation of myosin heavy chain. Pressurization at 100 MPa promoted the shift of α-helix structures to β-sheet and β-turn as compared with the other pressure levels. TPA values were higher in gels made at 100 MPa than at 300 or 600 MPa. Low pressure levels, then, increased the heat-induced gelling capacity of crab meat, improving the texture through modification of its protein structure.Industrial relevanceHigh pressure processing (HPP) technology has been successfully applied to several seafood products, both for processing and storage. However, in the case of blue crab meat it is important to study the effect of HPP on protein functional properties such as gelling capacity in order to optimize processing parameters for the preparation of high-quality restructured products. This paper reports the development of a HPP process (100, 300 and 600 MPa/5 min 40 °C/30 min + 90 °C/20 min) prior to thermal gelling for the preparation of crab meat gels. The application of 600 MPa produced considerable protein aggregation of gels, whereas with pressures below 300 MPa protein functionality can be modified to produce crab meat gels with adequate brightness, TPA values and a fresh, high-quality appearance. These results could provide a basis for further pressurization applications in the crab industry to create new seafood product analogues based on this kind of crab meat.     

Assessing the Impact of High-Pressure Processing on Selected Physical and Biochemical Attributes of White Cabbage (Brassica oleracea L. var. capitata alba)

The aim of this study was to investigate the effect of combined pressure/temperature treatments (200, 400 and 600 MPa, at 20 and 40 °C) on key physical and chemical characteristics of white cabbage (Brassica oleracea L. var. capitata alba). Thermal treatment (blanching) was also investigated and compared with high-pressure processing (HPP). HPP at 400 MPa and 20–40 °C caused significantly larger colour changes compared to any other pressure or thermal treatment. All pressure treatments induced a softening effect, whereas blanching did not significantly alter texture. Both blanching and pressure treatments resulted in a reduction in the levels of ascorbic acid, effect that was less pronounced for blanching and HPP at 600 MPa and 20–40 °C. HPP at 600 MPa resulted in significantly higher total phenol content, total antioxidant capacity and total isothiocyanate content compared to blanching. In summary, the colour and texture of white cabbage were better preserved by blanching. However, HPP at 600 MPa resulted in significantly higher levels of phytochemical compounds. The results of this study suggest that HPP may represent an attractive technology to process vegetable-based food products that better maintains important aspects related to the content of health-promoting compounds. This may be of particular relevance to the food industry sector involved in the development of convenient novel food products with excellent functional properties.     

Extending shelf life of desalted cod by high pressure processing

Salted fish need to be rehydrated before eaten, but rehydrated fish have a relatively short shelf life. To increase the shelf life the products can e.g. be frozen, packed in modified atmosphere or processed by high pressure (HPP). Here, rehydrated cod was packed with different packaging regimes; in vacuum, with CO₂ emitter or in modified atmosphere [MAP], either alone or in combination with HPP. A shelf life study was performed, and headspace gas composition, drip loss, pH, colour, texture and microbial counts were assessed in the packaged and processed portions. The results showed that a shelf life of minimum 49 days can be obtained by treating the rehydrated cod by HPP or by combining HPP with modified atmosphere or in combination with a CO₂ emitter. The results of this study have shown that different packaging and processing methods can increase the shelf life of desalted cod.Industrial relevanceThe growing trend and availability of “ready to cook” products are forcing the food industry to increase production of convenience products. Today desalted saltfish or clipfish need to be consumed immediately, stored chilled for a few days, stored frozen or being packed and/or processed to extend its shelf life. The use of high pressure processing represents a promising strategy to enhance the shelf-life of fish products. This study shows that HPP alone or combined with CO₂ can extend the shelf life of rehydrated cod. Hence, these results can open up for new products.     

Use of dietary vitamin E and selenium (Se) to increase the shelf life of modified atmosphere packaged light lamb meat

The aim of this work was to determine the increase in the shelf life of modified atmosphere packaged fresh lamb meat due to the effect of dietary vitamin E and selenium supplementation on colour and lipid oxidation. 128 lambs were fed on a concentrate with standard levels of vitamin E (C), a concentrate enriched with vitamin E (V), a concentrate with sodium selenite (S) and a concentrate enriched with both vitamin E and sodium selenite (VS). The lambs were slaughtered at 27.3±1.45 kg LW, and chops stored on MAP for 7, 9, 11 and 13 days. CIELab colour and TBARs were studied on these days. Use of dietary vitamin E extended the shelf life a further 4 days from the commercial sell-by date in terms of lightness, hue angle, metmyoglobin formation and lipid oxidation. Selenium could be used to increase the lightness of meat without vitamin E supplementation in lambs' diets.     

Impact of Thermal and Pressure-Based Technologies on Carotenoid Retention and Quality Attributes in Tomato Juice

The aim of this study was to investigate the impact of thermal processing (TP) (90 °C, 90 s), high-pressure processing (HPP) (600 MPa, 46 °C, 5 min), and high-pressure homogenization (HPH) (246 MPa, 99 °C, <1 s) on product quality parameters, specifically carotenoid content, and physicochemical attributes of particle size, color, viscosity, total soluble solids, and pH in tomato juice. Unprocessed tomato juice was used as control. The four major species of carotenoids (lycopene, β-carotene, phytoene, and phytofluene) in tomato juice were analyzed by HPLC. The content of total lycopene, all-trans-lycopene, cis-lycopene isomers,  phytoene, and phytofluene, in TP-, HPP-, and HPH-treated tomato juice did not significantly differ from that in unprocessed (control) juice. Significant reduction in β-carotene content was observed after TP treatment but not after HPP and HPH treatments. HPH significantly reduced tomato juice particle volume mean diameter from ～330 μm in control, HPP-, and TP-treated tomato juices to ～17 μm. A concomitant increase in apparent viscosity was observed in HPH-treated juice versus control. HPH-treated juice had increased redness (a*) and yellowness (b*) than that in control and HPP-treated tomato juices. These results indicate that high-pressure-based technologies (HPP and HPH) can preserve carotenoids as well as improve physicochemical properties.     

Effect of high-pressure processing on bacterial inactivation in açaí juices with varying pH and soluble solids content

This study evaluated microbial inactivation effects of high-pressure processing (HPP) applied to açaí juices formulated with varying pH and soluble solids content (SSC). Açaí juice with pH 4.3 and 2.9°Brix was initially inoculated with cocktails of 5 strains of E. coli O157:H7, Listeria monocytogenes or Salmonella spp. and processed at varying pressures (300, 400 and 600 MPa) and dwelling times (1 and 3 min) at 5 °C. The lethality at 400 MPa for 3 min was >6-log CFU/mL. Further inactivation was observed during storage under refrigeration in the populations of Salmonella spp. and L. monocytogenes. In order to study the influence of pH and SSC on inactivation of Salmonella spp. by HPP, pH of açaí juice samples was adjusted to a range between 4.0 and 5.5 and SSC was adjusted between 2.9 and 14.9°Brix. The ability of HPP to provide a 5-log reduction in the population of Salmonella spp. was reduced with increasing pH and SSC. Immediately after HPP the juices with pH 4.0 and 2.9°Brix presented >6-log reduction while the one with 8.9°Brix resulted in 5-log reduction. In one week of refrigerated storage (7 °C), the juices (pH 4.0–14.9°Brix and pH 4.5–2.9°Brix) also presented >6-log reduction in Salmonella spp. concentration. These results indicated that a less intense process (below commonly recommended commercial conditions - 600 MPa/3 min) could be applied for açaí juice thus assuring required safety, in addition to an extra microbial inactivation verified during refrigerated storage.Industrial relevanceOur results showed that viability of cells of pathogenic strains continues to fall after processing and that this effect can be reversed in higher pH and higher concentration of soluble solids. This observation can help the design of more efficient protocols for validation of HPP processing, leading to milder processing conditions that will allow reduction of maintenance and energy costs associated with HPP. In addition, our results help to clarify the criteria to be adopted in the microbiological validation of juices processed by high hydrostatic pressure.     

Characterisation of the carotenoids and assessment of the vitamin a value of Brasilian guavas (Psidium guajava L.)

The carotenoids of guava cultivar IAC-4 from the State of Sõ Paulo (southeastern Brasil) were identified as β-carotene, ζ-carotene, γ-carotene, zeinoxanthin, lycopene, 5,6,5′,6′-diepoxy-β-carotene and 5,8-epoxy-3,3′,4-trihydroxy β-carotene. The principal pigment was lycopene, corresponding to 86% of the total carotenoid content (62 μg/g). β-carotene was present at 3·7 μg/g; consequently, the vitamin A was relatively low (617 IU/100g). The same carotenoids were encountered in guavas from the States of Ceará and Pernambuco (northeastern Brasil). Cis-γ-carotene and 5,8-epoxy-zeinoxanthin were also found in the samples from Pernambuco. While the lycopene contents of the northeastern fruits were equal to, or lower than, that found in guava IAC-4, the β-carotene level (5·5–11·9 μg/g) was higher, corresponding to higher vitamin A values (917–1983 IU/100 g). With respect to vitamin C, the amount detected in guava cultivar IAC-4 was much higher (97·7 mg/100 g) than those encountered in the northeastern guavas (9·2–52·2 mg/100 g).     

低糖胡萝卜果脯加工工艺及对β-胡萝卜素和维生素C含量的影响

目的研究以新鲜胡萝卜为原料,制作低糖胡萝卜果脯的加工工艺。方法以正交试验法研究工艺条件对β-胡萝卜素和维生素C含量的影响,并评价其感官指标。结果胡萝卜果脯最佳生产工艺组合：切片厚度0．8cm,糖液浓度50％,糖煮时间30min;渗糖液添加组分：25％蔗糖,25％果葡糖浆,0．5％柠檬酸,0．1％甜菊糖苷和0．4％明胶。结论最佳工艺条件下产品β-胡萝卜素含量达3．55mg／100g,维生素C保存率为51％。     

Effects of high pressure processing on antioxidant activity, and total carotenoid content and availability, in vegetables

High pressure processing (HPP) is a relatively new food preservation processing technology that enhances food safety and shelf-life without compromising organoleptic qualities. There has been little research on the impact of HPP on the nutritional and health-promoting properties of foods to date and most of it has focused on juices and purees of fruit such as oranges and tomatoes. The objective of this study was to determine the effects of HPP treatment at two pressure levels (400 MPa; 600 MPa) on antioxidant activity, total carotenoid content and carotenoid availability in vitro, of three commonly consumed vegetables. Antioxidant capacity and total carotenoid content differed between vegetables but were unaffected by HPP treatment. In vitro availability of specific carotenoids also varied greatly between vegetables (3–35%). HPP altered availability of carotenoids according to the type of vegetable treated and processing pressure applied, however the magnitude of the responses was minor.

Industrial relevance

This study provides further scientific evidence of the benefits of high pressure processing in retaining the nutritional attributes of fresh foods. Antioxidant activity and levels of carotenoids before and after exposure to high pressures (up to 600 MPa for 2 min) were essentially no different. Also, the data suggest that micronutrients and phytochemicals in certain vegetables may be made more bioavailable by high pressure treatment. From a nutritional perspective, high pressure processing is an attractive food preservation technology and clearly offers opportunities for horticultural and food processing industries to meet the growing demand from consumers for healthier food products.     

Influence of selected packaging materials on some quality aspects of pressure-assisted thermally processed carrots during storage

Role of packaging barrier properties and storage conditions on pressure-assisted thermally processed (PATP) carrot quality were investigated. Samples were packaged in pouches fabricated using three packaging materials (Nylon/EVOH/EVA, Nylon/EVA and MetPET/PE) and processed at 600 MPa and 110 °C for 10 minutes. Processed pouches were stored at 25 and 37 °C, and withdrawn over 12 weeks. Samples were analyzed for color, β-carotene and total plate count. Oxygen and water vapor transmission rates (OTR, WVTR), melting point and enthalpy of fusion of the packages were evaluated. PATP treatment resulted in product shelf-stability during storage. Packaging type and storage conditions significantly influenced the product color and β-carotene content. Nylon/EVOH/EVA package best preserved carrot quality. PATP increased OTR of the MetPET/PE and degraded carrot color and β-carotene during storage. Raw carrots had 11.13 mg/100g β-carotene content. PATP treatment followed by 12 weeks storage at 37 °C reduced the β-carotene content of carrots packaged in Nylon/EVOH/EVA, Nylon/EVA and MetPET/PE to 7.19, 0.04 and 0.06 mg/100g, respectively. Similarly, the red color of carrot samples (25.51 for raw carrots) decreased to 19.85, 3.44 and 7.20 for Nylon/EVOH/EVA, Nylon/EVA and MetPET/PE, respectively. The study demonstrated the importance of high barrier packaging materials in preserving PATP-treated carrot quality.     

Commercial application of high-pressure processing for increasing starter-free fresh cheese shelf-life

Different non-thermal technologies have been proposed to extend the shelf-life of solid food products, high-pressure processing (HPP) being one of the emerging technologies which has been most extensively studied. In this study, one of the first commercial industrial-scale applications of HPP on a starter-free fresh cheese, with the aim of increasing its shelf-life, is presented. The effect of 500 MPa (5 min, 16 °C) on physico-chemical, microbial, colour, microstructure, texture and sensorial characteristics of starter-free fresh cheeses during cold storage of 21 days was studied. The results showed that pressurised cheeses presented a shelf-life of about 19–21 days when stored at 4 °C, whereas control cheese became unsuitable for consumption on day 7–8. On the other hand, cheese treated at 500 MPa was firmer and more yellow than the untreated one. However, these changes, which were detected by instrumental and sensory analysis, did not affect the preference for pressurised cheese. These results may lead to practical applications of HPP in the food industry to produce microbiologically safe cheese with extended shelf-life and sensory quality.     

Novel,non-thermal hydrodynamic cavitation of orange juice: Effects on physical properties and stability of bioactive compounds

Effect of hydrodynamic cavitation (HC) at pressure 3–15 bar and treatment time5–25 min on physical and chemical qualities of orange juice was investigated. Processing parameters were optimized on the basis of retention of vitamin C and antioxidant activity; inactivation of pectin methyl esterases (PME) and peroxidase (POD) enzyme and stability of pH, °Brix, viscosity, titratable acidity and total color difference. HC of orange juice at 5 bar 15 min and 13 bar 10 min resulted into maximal overall desirability at 0.52 and 0.40 respectively. No significant change in °Brix, pH, titratable acidity for fresh and cavitated orange juice was observed. Only 21% and 13% of reduction in PME and POD respectively was recorded. A 94% and 91% of antioxidant activity and vitamin C retention was noted in both optimized samples. This study demonstrated that HC can produce orange juice more economically with better physical properties and nutritional value.Industrial relevanceThe demand for more natural, preservative free with highest nutritional bioactive containing juices has created a need of non-thermal processing. Hydrodynamic cavitation (HC) processing is novel, emerging and under explored technology for fruit juices. HC due to the formation of cavities and shock waves causes enzyme and microbial inactivation at low temperature while retaining natural bioactives with fresh-like organoleptic characteristics. It is believed worldwide that non thermal technologies like HC will be among the most cost effective, scalable and impactful liquid food processing technologies in the coming decades especially for commercial products.