New opportunities and perspectives of high pressure treatment to improve health and safety attributes of foods. A review

The Effect of High Pressure Techniques on the Stability of Anthocyanins in Fruit and Vegetables

Anthocyanins are a group of phenolic compounds responsible for red, blue and violet colouration of many fruits, vegetables and flowers. The high content of these pigments is important as it influences directly their health promoting properties as well as the sensory quality of the product; however they are prone to degradation by, inter alia, elevated temperature and tissue enzymes. The traditional thermal methods of food preservation cause significant losses of these pigments. Thus, novel non-thermal techniques such as high pressure processing, high pressure carbon dioxide and high pressure homogenization are under consideration. In this review, the authors attempted to summarize the current knowledge of the impact of high pressure techniques on the stability of anthocyanins during processing and storage of fruit and vegetable products. Furthermore, the effect of the activity of enzymes involved in the degradation of these compounds has been described. The conclusions including comparisons of pressure-based methods with high temperature preservation techniques were presented.

Effects of germination and high hydrostatic pressure processing on mineral elements, amino acids and antioxidants in vitro bioaccessibility, as well as starch digestibility in brown rice (Oryza sativa L.)

The effects of germination and high hydrostatic pressure (HHP) processing on the in vitro bioaccessibility of mineral elements, amino acids (AAs), antioxidants and starch in brown rice (BR) were investigated. Germinated BR (GBR) was obtained by incubating at 37°C for 36h and then subjected to HHP treatments at 0.1, 100, 300 and 500MPa for 10min. The in vitro bioaccessibility of calcium and copper was increased by 12.59-52.17% and 2.87-23.06% after HHP, respectively, but bioaccessible iron was decreased. In addition, HHP significantly improved individual AAs, particularly indispensable AAs and gama-aminobutyric acid, as well as bioaccessible total antioxidant activities and starch resistance to enzymatic hydrolysis. However, germination greatly increased starch digestibility. Atomic force microscopy characterization suggested an obvious structural change in bran fraction at pressures above 300MPa. These results can help to understand the effects of germination and HHP technologies on nutrients bioaccessibility and develop appropriate processing conditions.

Stability of polyphenols in chokeberry juice treated with gas phase plasma

Chokeberry juice was subjected to cold atmospheric gas phase plasma and changes in hydroxycinnamic acids, flavonols and anthocyanins were monitored. Plasma treatments were carried out under different treatment times and juice volumes under constant gas flow (0.75dm(3)min(-1)). The results were compared against control (untreated) and pasteurized chokeberry juice (80°C/2min). During pasteurization, the most unstable were hydroxycinnamic acids with losses of up to 59%, while flavonols and anthocyanins increased by 5% and 9%, respectively. On the contrary, plasma treated chokeberry juice showed higher concentrations of hydroxycinnamic acids and 23% loss of anthocyanins in comparison to untreated juice. In order to obtain the optimal cold plasma treatment parameters principal component and sensitivity analysis were used. Such parameters can be potentially used for pasteurization in terms of phenolic stability of chokeberry juice. Optimal treatment was at 4.1min and sample volume of 3cm(3).

Physical and structural changes induced by high pressure on corn starch, rice flour and waxy rice flour

The impact of high pressure (HP) processing on corn starch, rice flour and waxy rice flour was investigated as a function of pressure level (400MPa; 600MPa), pressure holding time (5min; 10min), and temperature (20°C; 40°C). Samples were pre-conditioned (final moisture level: 40g/100g) before HP treatments. Both the HP treated and the untreated raw materials were evaluated for pasting properties and solvent retention capacity, and investigated by differential scanning calorimetry, X-ray diffractometry and environmental scanning electron microscopy. Different pasting behaviors and solvent retention capacities were evidenced according to the applied pressure. Corn starch presented a slower gelatinization trend when treated at 600MPa. Corn starch and rice flour treated at 600MPa showed a higher retention capacity of carbonate and lactic acid solvents, respectively. Differential scanning calorimetry and environmental scanning electron microscopy investigations highlighted that HP affected the starch structure of rice flour and corn starch. Few variations were evidenced in waxy rice flour. These results can assist in advancing the HP processing knowledge, as the possibility to successfully process raw samples in a very high sample-to-water concentration level was evidenced.

INDUSTRIAL RELEVANCE

This work investigates the effect of high pressure as a potential technique to modify the processing characteristics of starchy materials without using high temperature. In this case the starches were processed in the powder form - and not as a slurry as in previously reported studies - showing the flexibility of the HP treatment. The relevance for industrial application is the possibility to change the structure of flour starches, and thus modifying the processability of the mentioned products.

High-Pressure-Assisted Enzymatic Release of Peptides and Phenolics Increases Angiotensin Converting Enzyme I Inhibitory and Antioxidant Activities of Pinto Bean Hydrolysates

Pinto bean protein concentrate was hydrolyzed by subtilisins at 0.1, 100, and 200 MPa and 50 °C for 15 min. Alcalase hydrolysis at 100 MPa led to higher ACE inhibition, reducing power, and free radical scavenging activity of hydrolysates. However, hydrolysate obtained by Savinase at 200 MPa showed the best ACE-inhibitory and radical scavenging activities. Proteolysis by Savinase at 200 MPa was considered the most effective treatment to increase small peptides (<3 kDa), flavonoids, total phenolic compounds, and oxygen radical absorbance capacity in hydrolysates. In this hydrolysate, small phaseolin fragments with reported ACE-inhibitory and antioxidant sequences were identified. Catechin, pelargonidin 3-glucoside, and ferulic acid were the main phenolic compounds. Hihg-pressure-assisted hydrolysis of common bean protein concentrates would provide benefits in the production of functional hydrolysates providing higher functionality and added value to the resulting hydrolysate due to synergistic effects of bioactive peptides and soluble phenolics.