Mario Pérez-Won

Effect of high hydrostatic pressure on functional properties and quality characteristics of Aloe vera gel (Aloe barbadensis Miller).

The aim of this study was to evaluate the effects of high hydrostatic pressure treatment at three pressure levels (300, 400 and 500Mpa) on the functional and quality characteristics of Aloe vera gel including vitamin C and E, aloin, minerals, phenolic content and antioxidant activity. The results show that HHP exerted a clear influence on minerals content, vitamin C and E content, antioxidant activity, total phenolic and aloin content. After 35days of storage all treated samples presented a decrease in mineral content, except for phosphorus. Total phenolic content and vitamin C and E content decreased at high pressures (500MPa), while all pressurised samples showed a higher antioxidant activity and aloin content than untreated sample after 35days of storage. The maximum values of antioxidant activity and aloin were 6.55±1.26μg/ml at 300MPa and 24.23±2.27mg/100g d.m. at 400MPa.

Effects of high hydrostatic pressure (HHP) on the protein structure and thermal stability of Sauvignon blanc wine

Protein haze development in bottled white wines is attributed to the slow denaturation of unstable proteins, which results in their aggregation and flocculation. These protein fractions can be removed by using bentonite; however, a disadvantage of this technique is its cost. The effects of high hydrostatic pressure (HHP) on wine stability were studied. Fourier transform infrared spectroscopy experiments were performed to analyse the secondary structure of protein, thermal stability was evaluated with differential scanning calorimetry, while a heat test was performed to determine wine protein thermal stability. The results confirmed that high pressure treatments modified the α-helical and β-sheet structures of wine proteins. Throughout the 60 days storage period the α-helix structure in HHP samples decreased. Structural changes by HHP (450 MPa for 3 and 5 min) improve thermal stability of wine proteins and thus delay haze formation in wine during storage.

Microbiological stabilization of Aloe vera (Aloe barbadensis Miller) gel by high hydrostatic pressure treatment.

The effect of high hydrostatic pressure (HHP) treatment (300, 400 and 500 MPa for 1 and 3 min at 20 °C) on the microbiological shelf-life and microbiota composition of Aloe vera gel during 90 days of storage at 4 °C was investigated. Aerobic mesophilic and psychrotrophic bacteria, as well as moulds and yeasts, were enumerated after HHP treatment and through cold storage. Randomly selected isolates from the count plates were identified by standard methods and the API identification system. Results showed that HHP treatment at or over 400 MPa for 3 min were effective to keep the microbial counts to undetectable levels during the whole storage period, and consequently the microbiological shelf-life of A. vera gel was extended for more than 90 days at 4 °C. The microbiota in the untreated A. vera gel was dominated by Gram-negative bacteria (mostly Rahnella aquatilis) and yeasts (mostly Rhodotorula mucilaginosa). In contrast, Gram-positive bacteria tentatively identified as Arthrobacter spp. and Micrococcus/Kocuria spp. were the predominant microorganisms in samples pressurized at 300 MPa for 1 and 3 min, while Bacillus megaterium predominating in samples treated at 400 MPa for 1 min. At 400 MPa for 3 min and above, the microbial growth was completely suppressed during at least 90 days; however, viable spore-formers were detected by enrichment.

Effects of Ultra High Pressure on Bay Scallop (Aequipecten irradians) Adductor Muscles

The aim of this study was to evaluate the effects of ultra high pressure (UHP) on the adductor muscles of bay scallops (Aequipecten irradians) pertaining to certain physicochemical characteristics and microstructure. UHP treatment was applied at 200MPa and 400MPa, each application with one pulse and a holding time of 10min, or 2 pulses and a holding time of 5min per pulse, in a continuous or oscillation mode. Determination of textural parameters and L*, a* and b* colour parameters were carried out and compared with untreated scallops. Microstructure was observed using a scanning electronic microscopy (SEM) technique and, for microbial analyses, a total plate count was performed. SEM showed that UHP treatments induced a size reduction of the honeycomb structure of myofibres, giving a more compact appearance to the structure. Colour and compressibility enhanced by pressure treatment, however loss of hardness was observed. UHP treatments also reduced the initial load in total plate count of microorganisms to 10cfu/g. UHP is a competitive technology in food processing and ready for use on this high-priced seafood product.

Chemical and physical properties of aloe vera (Aloe barbadensis Miller) gel stored after high hydrostatic pressure processing

O objetivo deste estudo foi avaliar o efeito da aplicacao de altas pressoes hidrostaticas (150, 250, 350, 450 e 550 MPa) aplicadas durante 5 minutos sobre a atividade antioxidante, concentracao de polifenois totais, cor, firmeza, taxa de reidratacao e capacidade de retencao de agua do gel de aloe vera armazenado durante 60 dias a 4 °C. As propriedades analisadas do gel pressurizado mostraram mudancas significativas depois de armazenadas. Para pressoes de 550 Mpa, registrou-se o maior aumento de polifenois totais. No entanto, observou-se uma diminuicao da capacidade antioxidante em todas as amostras, em comparacao com a amostra nao tratada (p < 0,05). As alteracoes de cor foram menores para pressoes entre 150 e 250 MPa. A aplicacao de altas pressoes hidrostaticas diminuiu a firmeza do gel, registrando-se o menor valor para 150 MPa (p < 0,05). Por outro lado, o tratamento sem pressao mostrou uma maior perda de firmeza, indicando que o tratamento por altas pressoes conserva esta propriedade. A aplicacao de altas pressoes evidenciou modificacoes da matriz do alimento, avaliadas como taxa de reidratacao e capacidade de retencao de agua.

Efecto de la aplicación de alta presion hidrostática sobre la inactivación microbiana y las propiedades fisicoquímicas de arilos de granada

El objetivo de este trabajo fue evaluar el efecto de la APH sobre la vida útil microbiológica y parámetros físico-químicos (pH, acidez, actividad antioxidante, contenido de polifenoles, SST y color) de arilos de granada durante su almacenamiento a temperatura de refrigeración. Se aplicaron tratamientos de 350, 450 y 550 MPa durante 30, 60 y 90 s, posteriormente las muestras se almacenaron a 4°C durante 35 días. Las muestras fueron sometidas a recuentos microbianos y análisis físico-químicos. Todos los tratamientos de APH ensayados lograron reducir la carga microbiana inicial (1,0 y 1,6 log UFC/g) a <1,0 log UFC/g. La vida útil se logró extender a más de 35 días, independientemente del tratamiento aplicado. El contenido de polifenoles totales y la actividad antioxidante de las muestras procesadas disminuyeron significativamente (p < 0,05) durante el tiempo de almacenamiento en comparación con la muestra control.

Pressure Effects on Seafoods

Pressure treatment, in combination with refrigeration storage and handling practices, can extend seafood product shelf life and can be effective in reducing microorganisms. This chapter will discuss the effects of high-pressure processing (HP) on seafood products which focused on the sensory and physical properties, microbiological activities, chemical constituents and nutritional values, and existing development patents based on these aspects.

Convective Drying of Osmo-Treated Abalone (Haliotis rufescens) Slices: Diffusion, Modeling, and Quality Features

The focus of this research was based on the application of an osmotic pretreatment (15% NaCl) for drying abalone slices, and it evaluates the influence of hot-air drying temperature (40–80°C) on the product quality. In addition, the mass transfer kinetics of salt and water was also studied. The optimal time of the osmotic treatment was established until reaching a pseudo equilibrium state of the water and salt content (290 min). The water effective diffusivity values during drying ranged from 3.76 to 4.75 × 10−9 m2/s for three selected temperatures (40, 60, and 80°C). In addition, experimental data were fitted by Weibull distribution model. The modified Weibull model provided good fitting of experimental data according to applied statistical tests. Regarding the evaluated quality parameters, the color of the surface showed a change more significant at high temperature (80°C), whereas the nonenzymatic browning and texture showed a decrease during drying process mainly due to changes in protein matrix and rehydration rates, respectively. In particular, working at 60°C resulted in dried samples with the highest quality parameters.

Effects of High Pressure Treatment on Physicochemical Quality of Pre- and Post-Rigor Palm Ruff (Seriolella Violacea) Fillets

ABSTRACT Fish and fish products are characterized for having a short shelf life. Nonthermal processing techniques such as high hydrostatic pressure (HHP) have increasingly been employed to extend shelf life of food products. The aim of this study was to evaluate changes on flesh physicochemical spoilage parameters (pH, total volatile bases (TVB-N), trimethylamine (TMA), thiobarbituric acid (TBA), and color) of palm ruff (Seriolella violacea) fillets in pre- and post-rigor conditions, subjected to two different HHP conditions: 450 MPa and 550 MPa, for 3 and 4 min each. Unpressurized and pressurized fillets were kept in chilled storage (4 ± 1°C) for 26 days to assess the effect of HHP on shelf life. pH and TBA values increased after HHP treatment and with storage time for both unpressurized and pressurized samples. This is attributable to pressure-induced lipid oxidation. Lightness (L*) values increased with pressure, where fish fillets had a cooked appearance. TMA and TVB-N values decreased after HHP treatment compared to the unpressurized samples, showing that HHP treatment is an efficient method to maintain the quality of palm ruff fillets. There was no clear difference between pre- and post-rigor in the parameters evaluated.