Citrus varieties

Citrus contains a range of highly beneficial bioactive compounds, such as polyphenols, carotenoids, and vitamins that show antimicrobial and antioxidant properties and help in building the body’s immune system. On consumption or processing, approximately 50% of the fruit remains as inedible waste, which includes peels, seeds, pulp, and segment residues. This waste still consists of substantial quantities of bioactive compounds that cause environmental pollution and are harmful to the ecosystem because of their high biological oxygen demand. In recent years, citrus cultivation and the production of processed foods have become a major agricultural industry. In addition to being a substantial source of economy, it is an ideal and sustainable and renewable resource for obtaining bioactive compounds and co-products for food and pharmaceutical industries. In the present article, the various methods of extraction, conventional and modern, as well as separation and isolation of individual bioactive compounds from the extraction mixture and their determination have been reviewed. This article presents both aspects of extraction methods, i.e., on a small laboratory scale and on an industrial mass scale. These methods and techniques have been extensively and critically reviewed with anticipated future
perspectives towards the maximum utilization of the citrus waste.
Keywords: citrus waste; citrus byproducts; essential oils; waste management; limonene; phenolics; flavonoids; citric acid; environment friendly extraction; phytochemical extraction and purification

Resumo A produção de citrinos encontra-se amplamente disseminada por todos os continentes, representando uma atividade económica geradora de milhões de euros. As crescentes exigências dos consumidores conduzem ao aparecimento de novas variedades, em detrimento das cultivares tradicionais. A produção de tangerineira 'Setubalense' (Citrus deliciosa) tem vindo a sofrer um acentuado declínio, mas os consumidores mais exigentes em aromas cítricos e fragrâncias intensas continuam a apreciar esta cultivar. Por isso, esta cultivar tem algum espaço comercial para mercados diferenciados em que se valorizam as cultivares tradicionais. Estas características e a sua época de maturação, que implica ser pouco afetada pela Ceratitis capitata, fazem da 'Setubalense' uma cultivar recomendável para o modo de produção biológico. Com o objetivo de caracterizar o padrão produtivo alternante e tendo por objeto de estudo um pomar de cinco anos de tangerineira 'Setubalense' enxertado sobre citranjeira 'Troyer' [Citrus sinensis (L.) Osbeck × Poncirus trifoliata L.], foi avaliada a composição da rebentação e da floração nos anos de safra e de contrassafra. A intensidade e as características da rebentação dependem do quadrante da árvore e do ano (safra ou contrassafra). Nos anos de safra a percentagem de nós rebentados oscila entre 67,6 a 79,5%, que contrasta com os 25,4 a 28,2% dos anos de contrassafra, função do quadrante analisado. Nos anos produtivos os rebentos formados são essencialmente florais e nos improdutivos quase exclusivamente vegetativos. A formação de elevado número de flores nos anos de safra conduz a uma intensa abcisão de órgãos generativos. O número de folhas formadas por cada 100 nós é similar nos anos de safra e de contrassafra. Os resultados obtidos refletem o padrão alternante desta cultivar, evidenciando o cuidado particular que esta cultura tem de ter na sua condução. Abstract Characterization of the sprouting of 'Setubalense' mandarin in " on-crop " and " off-crop " years The citrus production is widespread throughout all continents, representing an economic activity, generative of billions of euros. The increasing demands of consumers lead to the emergence of new cultivars at the expense of traditional cultivars. The production of 'Setubalense' mandarin (Citrus deliciosa) has suffered a sharp decline, but consumers who require more intense citrus aromas and fragrances continue to enjoy this cultivar. Therefore, this cultivar has a commercial space for different markets that value the traditional cultivars. These characteristics and its time of maturity, which implies being little affected by Ceratitis capitata, make 'Setubalense' a cultivar recommended for organic farming. Aiming to characterize the alternating reproductive pattern, and having as object of study a 5-year-old orchard of 'Setubalense' mandarin grafted on 'Troyer' citrange [Citrus sinensis (L.) Osbeck × Poncirus trifoliata L.] we evaluated the composition of the tree sprouting and flowering in the years " on " and " off " of the alternate bearing cycle. The intensity and characteristics of spring sprouting depends on the tree quadrant and the year (" on " and " off " of the alternate bearing cycle). In the years "on" the percentage of sprouted nodes ranges from 67.6 to 79.5%, which contrasts with the 25.4 to 28.2% of the year "off", depending on the analyzed quadrant. In the productive years formed sprouts are mostly floral, and in the unproductive years the sprouts are almost exclusively vegetative. The formation of a large number of flowers in the year "on" leads to an intense abscission of the generative organs. The number of leaves per 100 nodes is similar in years "on" and "off". The results reflect the alternating bearing pattern of this cultivar, showing that it is necessary to pay particular attention in its management.