Light-induced alterations of pineapple (Ananas comosus [L.] Merr.) juice volatiles during accelerated ageing and mass spectrometric studies into their precursors

Solid-Phase Microextraction Techniques and Application in Food and Horticultural Crops

Solid-phase microextraction (SPME) is a sample preparation technique which utilizes small amounts of an extraction phase for the extraction of target analytes from investigated sample matrices. Its simplicity of use, relatively short sample processing time, and fiber reusability have made SPME an attractive choice for many analytical applications. SPME has been widely applied to the sampling and analysis of environmental, food, aromatic, metallic, forensic, and pharmaceutical samples. Solid phase microextraction is used in horticultural crops, for example, to determine water and soil contaminants (pesticides, alcohols, phenols, amines, herbicides, etc.). SPME is also used in the food industry to separate biologically active substances in food products for various purposes, for example, disease prevention, determining the smell of food products, and analyzing tastes. SPME has been applied to forensic analysis to determine the alcohol concentration in blood and that of sugar in urine. This method has also been widely used in pharmaceutical analysis. It is a solvent-free sample preparation technique that integrates sampling, isolation, and concentration. This review focuses on recent work on the use of SPME techniques in the analysis of food and horticultural crops.

Nonthermal pasteurization of pineapple juice: A review on the potential of achieving microbial safety and enzymatic stability

Pineapple juice is preferred by consumers for its unique aroma and flavor that come from a set of amino acids, amines, phenolic compounds, and furanone. The juice is susceptible to spoilage, and a common practice is to pasteurize it at 70-95°C for 0.5-5 min. However, the characteristic flavors and phytochemicals are negatively influenced by the intense time-temperature treatment. To retain the thermosensitive compounds in the juice, some nonthermal technologies such as high-pressure processing, pulsed electric field, pulsed light, ultrasound, and ultraviolet treatments have been explored. These techniques ensured microbial safety (5-log reduction in E. coli, S. Typhimurium, or S. cerevisiae) while preserving a maximum ascorbic acid (84-99%) in the juice. The shelf life of these nonthermally treated juice varied between 14 days (UV treated at 7.5 mJ/cm² ) and 6 months (clarified through microfiltration). Moreover, the inactivation of spoilage enzyme in the juice required a higher intensity. The present review discusses the potential of several nonthermal techniques employed for the pasteurization of pineapple juice. The pasteurization ability of the combined hurdle between mild thermal and nonthermal processing is also presented. The review also summarizes the target for pasteurization, the plan to design a nonthermal processing intensity, and the consumer perspective toward nonthermally treated pineapple juice. The techniques are compared on the common ground like safety, stability, and quality of the juice. This will help readers to select an appropriate nonthermal technology for pineapple juice production and design the intensity required to satisfy the manufacturers, retailers, and consumers.

Pineapple by-products as a source of bioactive compounds with potential for industrial food application

Pineapple is a tropical fruit consumed fresh or processed into various food products. However, the peel and crown of this fruit are not industrially exploited, thus generating tons of by-products that represent an economic and environmental concern. In order to promote the upcycling of these by-products, this work aimed to characterize the phenolic profile of its hydroethanolic extracts obtained from pineapple peel and crown leaves and to evaluate their in vitro bioactivity. The HPLC-DAD-ESI/MS analysis allowed the identification of 25 phenolic compounds, including phenolic acids and flavonoids. The antioxidant, cytotoxic, and antimicrobial activity assays highlighted the peel extract as the most promising and, therefore, it was incorporated into a traditional Portuguese pastry cake as a functional ingredient. The nutritional parameters of the developed food were not affected by the incorporation of the extract, but it promoted the antioxidant activity during its shelf-life. Overall, pineapple peel and crown appeared as promising by-products to be exploited by the food industry, which can be achieved through a circular economy approach.

Prunus lusitanica L. Fruits as a Novel Source of Bioactive Compounds with Antioxidant Potential: Exploring the Unknown

Prunus lusitanica L., also known as Portuguese laurel or locally known as ‘azereiro’, is a rare species with ornamental and ecological value. Only two studies regarding the bioactivity and chemical composition of its leaves were reported to date. Thus, the present study aims to qualitatively and quantitatively evaluate the phenolic profile, through HPLC-PAD-ESI-MS/MS (high-performance liquid chromatography–photodiode array detection–electrospray ionization tandem mass spectrometry), as well as the radical scavenging capacity, through ABTS (2,2’-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid) and DPPH (2,2-diphenyl-1 picrylhydrazyl), and the reducing power (FRAP, ferric reducing antioxidant power) assays, of P. lusitanica fruits during a 4-year study. In total, 28 compounds were identified and quantified in the fruits, including 21 hydroxycinnamic acids (60.3%); 2 flavan-3-ols (27.9%), 2 anthocyanins (10.5%), 2 flavonols (1.0%), and 1 secoiridoid (0.3%). High antioxidant capacity was observed, with ABTS values ranging from 7.88 to 10.69 mmol TE (Trolox equivalents)/100 g fw (fresh weight), DPPH values from 5.18 to 8.17 mmol TE/100 g fw, and FRAP values from 8.76 to 11.76 mmol TE/100 g fw. According to these results, it can be concluded that these are rich sources of phenolic compounds with very promising antioxidant capacity and, therefore, with potential applications in the food and/or phytopharmaceutical sectors.

Sustainable utilization of pineapple wastes for production of bioenergy, biochemicals and value-added products: A review

Agricultural residues play a pivotal role in meeting the growing energy and bulk chemicals demand and food security of society. There is global concern about the utilization of fossil-based fuels and chemicals which create serious environmental problems. Biobased sustainable fuels can afford energy and fuels for future generations. Agro-industrial waste materials can act as the alternative way for generating bioenergy and biochemicals strengthening low carbon economy. Processing of pineapple generates about 60% of the weight of the original pineapple fruit in the form of peel, core, crown end, and pomace that can be converted into bioenergy sources like bioethanol, biobutanol, biohydrogen, and biomethane along with animal feed and vermicompost as described in this paper. This paper also explains about bioconversion process towards the production of various value-added products such as phenolic anti-oxidants, bromelain enzyme, phenolic flavour compounds, organic acids, and animal feed towards bioeconomy.

Effect of Pulsed Light Treatment on Natural Microbiota, Enzyme Activity, and Phytochemical Composition of Pineapple (Ananas comosus [L.] Merr.) juice

The effect of pulsed light (PL) on numerous important quality characteristics of pineapple juice was studied and compared with untreated and thermally pasteurised samples. The laboratory scale PL batch system used was operated with each three different voltages (1.8, 2.1, and 2.4 kV) and numbers of pulses (47, 94, and 187). Treatments with 2.4 kV and either 94 or 187 pulses (757/1479 J·cm−2) resulted in a 5-log reduction in aerobic mesophiles and the yeast and mould counts. Peroxidase was more resistant to PL than polyphenol oxidase, whereas the bromelain activity was completely retained in all PL-treated juices. Colour and antioxidant capacity were minimally affected, while vitamin C, genuine pineapple furanones, and phenolic compounds declined. In contrast, thermal pasteurisation was more detrimental to colour, antioxidant capacity, and vitamin C content, but resulted in a superior inactivation of microorganisms and enzymes and retention of phenolic compounds. Principal component analysis (PCA) permitted the differentiation of fresh, thermally pasteurised, and all PL-treated juices. PCA on the basis of the individual juice constituents additionally arranged the latter juices according to the number of pulses and voltage levels applied, particularly promoted by the oxidation of ascorbic to dehydroascorbic acid. In conclusion, PL treatment represents a promising new alternative to conventional thermal preservation techniques, whereby the inactivation of deteriorative enzymes may be further optimised.

Degradations of aroma characteristics and changes of aroma related compounds, PPO activity, and antioxidant capacity in sugarcane juice during thermal process

Alterations of aroma properties and aroma-related attributes of sugarcane juice during thermal processing under different temperatures (90, 100, and 110 ℃) and treating time (10 s, 20 s, and 30 s) were assessed in this study. Changes in the volatility of aroma compounds were extremely complicated and respected to thermal processing conditions. Fructose, serine, and glutanic acid of sugarcane juice were increased at first and decreased at the end of treatment at high temperature. Phenolic compounds and PPO activity presented the decrease trends throughout the thermal treatment. The thermal processing of sugarcane juice could be roughly divided into three stages based on the cluster analysis of all the data in this study. Sugars, amino acids, and phenolic compounds might be important potential precursors of aroma deteriorating reactions. The comprehensive analysis of aroma relevant compounds and enzyme activities was beneficial for the investigation of degradation mechanism of aroma for sugarcane juice, and providing a theoretical basis for optimization of juice processing. PRACTICAL APPLICATION: This study demonstrated the changing process of aroma quality and associated compounds in sugarcane juice during thermal processing. This could help to find out the reasons of aroma degradations in sugarcane juice and other thermal sensitive juice. Our manuscript created a paradigm for future studies on the aroma quality control and parameter optimization during the processing of fruit and vegetable juice.

Integral Valorization of Pineapple (Ananas comosus L.) By-Products through a Green Chemistry Approach towards Added Value Ingredients

Industrial by-products are produced every day through fruit processing industries. Pineapple is not an exception; when processed, around 60% (w/w) of its weight are peels, stem, trimmings, and crown, the only used fruit part for human consumption. Due to high concerns of sustainability in the food system and negative high impact of human practice in the environment, a strategy has to be developed. Therefore, a green chemistry approach was applied to pineapple by-products to make an integrated valorization by the extraction of bioactive molecules. Two pineapple by-products (peels and stems) were studied, applying a green chemistry approach, which means the non-use of organic solvents or extreme methodologies. A subdivision of each by-product was done by the application of a juice machine. The peels and stems in the fresh state were ground separately, creating two fractions for each by-product—a juice and a wet pulp (press cake). The press cake was characterized, dried, and ground to create a fine powder flour. To the juice, a precipitation methodology with polysaccharides was applied, which allowed the bromelain separation (developing of an enzymatic fraction) from the fruit juice. The enzymatic extract was freeze-dried, and the juice was spray-dried, developing two more fine powders. Thus, three new ingredients were produced from each by-product, creating a total of six new ingredients. Overall, the enzymatic fractions represented around 0.26% (w/w) of pineapple weight. Pineapple stem juice represented 4.8% (w/w), and peel juice represented 17.3% (w/w). Pineapple stem flour represented 3.1% (w/w), and peel flour represented 11.4% (w/w) of the total pineapple weight. To valorize the by-products juices, a full characterization was performed of bioactive molecules and biological activities. When comparing the two juices, the peel juice showed lower content of total phenolic compounds, lower antioxidant capacity, and lower content of vitamin C. The different phenolic compounds were identified by HPLC analysis in the two pineapple by-products juices. However, the same compounds in both juices were quantified (chlorogenic, caffeic, and ferulic acids). On the other hand, the by-products flours had a high content of insoluble dietary fiber (IDF), mainly cellulose and hemicellulose. Therefore, the approach applied in this work opens the door to the production of green products, as a result of by-products valorization. This could be applied not only in the food industry but also in the nutraceutical and cosmetic industries.