Optimization of Thermoultrasound Conditions for the Processing of A Prickly Pear Juice Blend (Opuntia Ficus Indica) Using Response Surface Methodology

Impact of Fermentation and Pasteurization on the Physico-Chemical and Phytochemical Composition of Opuntia ficus-indica Juices

Opuntia ficus-indica fruits are a source of valuable compounds, presenting a high nutritional value and several health benefits. However, due to its low shelf life and increased production, there are considerable post-harvest losses of this cactus fruit. So, ways need to be found to drain the increased production of this fruit that is being wasted. The chemical composition of prickly pear makes it an appealing substrate for fermentation. This study investigates the production of fermented beverages produced from Opuntia ficus-indica cv 'Rossa' and evaluates the effects of different fermentation times (18 and 42 h) and post-fermentation pasteurization by high-pressure (500 MPa for 10 min) and temperature (71.1 °C for 30 s) on the physico-chemical and biological characteristics of the produced beverages. According to the results, the beverage produced from 48 h of fermentation has an alcohol content value of 4.90 ± 0.08% (v/v) and a pH of 3.91 ± 0.03. These values contribute to an extended shelf life and improved organoleptic characteristics compared to the sample fermented for 18 h. Additionally, the longer fermentation resulted in 50% fewer total soluble solids, 90% less turbidity, and lower pH when compared to the sample fermented for 18 h. Moreover, overall, high-pressure processing demonstrates better retention of "fresh-like" characteristics, along with higher levels of phytochemical compounds and antioxidant capacity, similar to those observed in the juice for SO^•- and NO^•-scavenging abilities.

Opuntia ficus-indica Fruit: A Systematic Review of Its Phytochemicals and Pharmacological Activities

The use of Opuntia ficus-indica fruits in the agro-food sector is increasing for a multiplicity of players. This renewed interest is, in part, due to its organoleptic characteristics, nutritional value and health benefits. Furthermore, industries from different sectors intend to make use of its vast array of metabolites to be used in different fields. This trend represents an economic growth opportunity for several partners who could find new opportunities exploring non-conventional fruits, and such is the case for Opuntia ficus-indica. O. ficus-indica originates from Mexico, belongs to the Cactaceae family and is commonly known as opuntia, prickly pear or cactus pear. The species produces flowers, cladodes and fruits that are consumed either in raw or in processed products. Recent publications described that consumption of the fruit improves human health, exhibiting antioxidant activity and other relevant pharmacological activities through enzymatic and non-enzymatic mechanisms. Thus, we provide a systematic, scientific and rational review for researchers, consumers and other relevant stakeholders regarding the chemical composition and biological activities of O. ficus-indica fruits.

Effect of High-Pressure and Thermal Pasteurization on Microbial and Physico-Chemical Properties of Opuntia ficus-indica Juices

Opuntia fruits are recognized for their richness in nutrients and in bioactive compounds, being also highly appreciated by consumers as a juice. Nevertheless, without further processing, prickly pear juices have a short shelf-life, hampering their commercial use. In this work, thermal (TP) and high-pressure (HPP) pasteurization were applied to juices from Opuntia ficus-indica cultivars ‘Rossa’, ‘Gialla’, and ‘Bianca’ to understand the impact of those methods on the microbial safety, physico-chemical properties, and the nutritional content of the samples, over storage at 4 °C. In general, thermal pasteurization at 71.1 °C for 30 s increased the shelf-life by 22 days, and high-pressure pasteurization at 500 MPa for 10 min increased the shelf-life by 52 days with regard to microbial growth as well as maintenance of physical-chemical characteristics. The application of these two pasteurization methods delayed changes in the physico-chemical characteristics of the juices, with a more pronounced effect on the titratable acidity, °Brix and browning. For the same periods of time, the application of pasteurization methods decreased the variation in these quality parameters by around 75%. Similarly, these methods were shown to have the same effect on the polyphenolic concentration as well as the antioxidant activity of the juices. In particular, HPP was more efficient in preventing a decrease in °Brix and increase in titratable acidity, which normally negatively affect the flavor of the juices.

Quality Preservation of Ready-to-Eat Prickly Pears by Peels Recycling

In the current study, prickly pear peel was advantageously recycled to preserve fruit quality. Specifically, the investigated by-products were transformed into powder and then loaded into an alginate-based solution to be applied as coating to peeled prickly pears, to give an example of sustainable minimally processed fruit. For comparison, uncoated fruit, and coated prickly pears without any powder were also prepared. During storage at refrigerated temperature, coated and uncoated samples were tested for weight loss, microbial and fungal proliferation, as well as for sensory quality acceptance. The results were interesting because great differences were found between coated and uncoated fruit, in that coating the fruit delayed weight loss and spoilage, compared to uncoated fruit. Between the simple coating and the coating with peel powder, slight differences were recorded in favor of the peel-enriched coating. In fact, it allowed the promotion of better fruit preservation, and sensory quality. Therefore, prickly pear peels, that represent abundant by-products during prickly pear processing, could be advantageously recycled to preserve fruit quality.

Optimization of incorporating κ-Carrageenan-based gels on improving cloud stability, physical stability, and viscosity of ready-to-drink mango juice

κ-Carrageenan gels were explored for improving the stability of ready-to-drink (RTD) mango juice.RTD mango juice with an acidity of 0.3% and a Brix of 18° was prepared. Two gels, bi-gel and hydrogel, were incorporated in RTD mango juice to study the effect of gel dosage, resting time, and homogenizing time on selected attributes (cloud and physical stability, and viscosity), determined using second-order Box-Behnken design, in combination with response surface methodology. The coefficient of determination values for all models was found to be higher than 90%. The fluid behavior of RTD mango juice after the addition of gels tends to fit Herschel-Bulkley's model. The behavior of RTD mango juice's fluid was found to change from shear thickening to shear thinning after the addition of gels. For hydrogel-based RTD mango juice, maximum cloud stability (3.012 abs), physical stability (66.49%) with minimum viscosity (4120 cP) resulted from optimized conditions of gel dosage (9 mL), resting time (1 h), and homogenizing time (33 s). For RTD mango juice, hydrogel can be preferred over bi-gel due to its melt-in-your-mouth sensation with high physical and cloud stability. PRACTICAL APPLICATION: Ready-to-drink mango juice is consumed by a large number of people worldwide. However, an increase in the storage period causes coagulation of the pulp particles, resulting in undesired distinct layers of pulp and water content. In this study, κ-Carrageenan gels were added to RTD mango juices to avoid such separation and improve cloud and physical stability. The findings from this study might serve as a roadmap for developing high-quality, stable RTD products.

Characterization of prickly pear juice by means of shelf life, sensory notes, physicochemical parameters and bio-functional properties

ABSTRACT

The objective of the present work was to characterize prickly pear juice prepared from prickly pear fruits of the wild cultivar in terms of shelf life (air and vacuum packaging), sensory stability (odour, taste, and appearance) physicochemical parameters (acidity, vitamin C, pH, electrical conductivity, total dissolved solids, specific weight, total sugar content, and colour coordinates L*, a*, b*) and bio-functional properties [in vitro antioxidant activity (AA%) and total phenolic content (TPC)]. For this purpose fruits were collected during August 2017 from 3 different geographical zones in Peloponnese. The shelf life of prickly juice was extended by 5 days in vacuum compared to air packaging, whereas it was found to be a rich source of phytochemicals and a natural antioxidant agent (AA of 67.33 ± 5.89-75.63 ± 4.41% and TPC of 3234.5 ± 978.2-7592.1 ± 2441.0 mg GAE L^-1), in relation to fruit geographical origin (P < 0.05). The exploitation of prickly pear juice is really a challenge.

GRAPHICAL ABSTRACT