Postharvest of Actinidia deliciosa cv. ‘Hayward’ and Actinidia chinensis cv. ‘Jintao’ - Effect of storage and shelf-life -

• Autor(a) principal: Rodrigues, Ricardo José Menezes
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10348/8686
• topic: Actinidia deliciosa; Actinidia chinensis; refrigeração; textura; qualidade; metabolitos secundários

Kiwifruit production kept growing each year on the last decades in Portugal, and the main production regions are Entre-Douro e Minho region followed by Beira Litoral. Interest on kiwifruit keeps increasing due to its high nutritional value when compared to other fruits. These fruits are often stored on normal (NA) or controlled (CA) atmosphere chambers which can extend its marketability and make them available during at least 6 months. Several physicochemical changes occur during maturation and ripening of this fruit with a higher or lower intensity according to the metabolic activity demonstrated, where modified storage atmospheres intend to keep low, as well as maintaining the fruit overall quality and marketability through time. On this master thesis, physicochemical assays were done to evaluate the postharvest progression of two species of kiwifruits, Actinidia deliciosa cv. ‘Hayward’ and Actinidia chinensis cv. ‘Jintao’, where ‘Hayward’ was stored on CA and NA chambers while ‘Jintao’ was only stored in a NA chamber. The objectives are focused on the differences occurred between CA and NA for ‘Hayward’ kiwifruits through time and its shelflife performance, as well as the differences between ‘Hayward’ and ‘Jintao’ through time and on their shelf-life performance. The kiwifruit’s weight, size, °Brix, pH, NaOH volume spent in titration, texture, skin and flesh colour, free-sugars concentrations, organic acids, antioxidant activity, vitamin C and carotenoids were all assessed during the experimental period of this work from November 2015 to March 2016. Following the objectives, a comparison was made between CA and NA for ‘Hayward’, the differences encountered between ‘Hayward’ and ‘Jintao’, as well as the shelf-life behaviour on a 7-day period. The predominant soluble sugars identified were fructose and glucose, and on lower concentrations sucrose and galactose, which tended to increase through time. Quinic and citric acids are predominant over malic and ascorbic acid with slight differences through time. Overall, CA provided better results than NA on preventing weight loss, keeping higher texture values, providing kiwifruits with more lightness and chroma, while no significant differences were found on °Brix, free-sugars, antioxidant activity and carotenoids; however, quinic acid was higher on NA. The main differences between cultivars were: an overall higher weight and firmness for ‘Hayward’; a general decrease of lightness; °Brix was clearly higher for ‘Jintao’; free-sugars were also present on higher concentrations on ‘Jintao’ as well as an overall higher antioxidant activity. On the 7-day shelf-life period, no significant differences were found on weight loss, a general decrease in chroma, and firmness decreased significantly, °Brix had an increasing trend, no significant differences were obtained in free-sugars, carotenoids and antioxidant activity while ascorbic acid had significantly decreased between the start and the end of shelf-life