Structural and Physicochemical Properties of Starch from Rejected Chestnut: Hydrothermal and High-Pressure Processing Dependence.

The quality standards for the export of chestnuts generate large quantities of rejected fruits, which require novel processing technologies for their safe industrial utilization. This study aimed to investigate the impact of high-pressure processing (HPP) and hydrothermal treatments (HT) on the physicochemical properties of rejected chestnut starch. Chestnuts were treated by HPP at 400, 500, and 600 MPa for 5 min and HT at 50 °C for 45 min. In general, all HPP treatments did not induce starch gelatinization, and their granules preserved the integrity and Maltese-cross. Moreover, starch granules' size and resistant starch content increased with the intensity of pressure. Native and HT chestnut starches were the most susceptible to digestion. HPP treatments did not affect the C-type crystalline pattern of native starch, but the crystalline region was gradually modified to become amorphous. HPP-600 MPa treated starch showed modified pasting properties and exhibited the highest values of peak viscosity. This study demonstrates for the first time that after HPP-600 MPa treatment, a novel chestnut starch gel structure is obtained. Moreover, HPP treatments could increase the slow-digesting starch, which benefits the development of healthier products. HPP can be considered an interesting technology to obtain added-value starch from rejected chestnut fruits.

Valorisation of rejected unripe plantain fruits of Musa AAB Simmonds: from nutritional characterisation to the conceptual process design for prebiotic production.

The increasing consumption of plantain fruits with specific quality standards generates high agricultural waste. This work aimed at valorising the rejected unripe pulp of Dominico-Hartón plantain fruits (Musa AAB Simmonds). The pulp was characterised physico-chemically, thermally and functionally. The data gathered experimentally and collected from different databases were used to design a production process of isomalto-oligosaccharides (IMO) syrup. The plantain flour contains high levels of starch (87 ± 2%) and amylose (31.2 ± 0.8%). The flour showed stability at high temperatures (pasting temperature of 79.26 ± 0.02 °C), allowing its use in high temperature processes. In vitro gastrointestinal digestion of the plantain flour showed that when cooked, the glycemic index of the flour increased from 47.7 ± 2.2 to 84.2 ± 1.8, while its resistant starch content only slightly decreased from 71.7 ± 1% to 52.6 ± 2%, suggesting that this type of flour preserves high content of dietary fibre after digestion. The conceptual process design showed that 24.48 g of IMO are theoretically obtained from 53.24 g of plantain flour maltose. These results suggest that the rejected plantain pulp holds high potential as an ingredient for the production of prebiotic compounds such as IMO.

Optimization of fish gelatin drying processes and characterization of its properties.

Fish skin is a raw material used for gelatin production. It can satisfy consumers with specific socio-cultural and religious needs. Different technologies have been studied for drying gelatin. Therefore, it is relevant to understand the influence of drying conditions on the final product. This study aims to optimize drying methods such as convection hot air alone and combined with infrared radiation to obtain gelatin from acoupa weakfish skin by using composite central rotational designs 22 and 23 and response surface methodology. The gelatin obtained from the optimized conditions were characterized based on their physical, chemical, technological, and functional properties. The desirability function results show the convection hot air as the most effective method when conducted at 59.14 °C for 12.35 h. Infrared radiation at 70 °C for 2.0 h and convective drying at 70 °C for 3.5 h were the best condition of the combined process. The gelatins obtained had gel strength of 298.00 and 507.33 g and emulsion activity index of 82.46 and 62.77 m2/g in the combined and convective methods, respectively, and protein content above 90%. These results indicate that the processes studied can be used to produce gelatin with suitable technological and functional properties for several applications.

Influence of grilling pretreatment and optimization of sous vide processing parameters on the physicochemical and microbiological quality of pirarucu fillet.

The demand for high-quality food products has promoted the study of techniques for its processing and conservation. The present research aimed to evaluate the influence of grilling pretreatment on the physical characteristics of pirarucu fillets and the heat transfer process by a computational modelling, and to optimize the sous vide process parameters. Before and after the sous vide process, the samples were analysed for microbiological, chemical and physical characteristics. There was no significant difference between the total experimental time of grilling and that obtained by computational modelling. Immersion in brine for 300 s in combination with grilling at 200 ℃/120 s was selected because of its water-holding capacity (%) 79.40 ± 0.31, texture (N) 1.91 ± 0.40 and value of L* 74.44 ± 0.38 in the fillets. Cooking at 60 ℃ for 568.8 s were the best sous vide parameters obtained, with highest water-holding capacity (%) 93.60, texture (N) 6.24, ΔE* 7.43, and with microbiological loads below 6 log CFU/g and 7 log MPN/g in the final product. Useful information obtained from this study highlighted the brine and grill pretreatment in combination with sous vide proved it is a potential solution for developing pirarucu products even at an industrial scale.