Study of the effect of high pressure processing on the potato frying process

• Autor(a) principal: Cruz, Cátia Sofia Dourado
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/27885
• topic: Potato; High pressure processing; Asparaginase; Frying; Acrylamide; Potato tuber; Fried potatoes

The frying process is the most used technique in potato processing before consumption. Some of the textural, nutritional, and sensory changes induced by frying are desirable, but others are harmful to human health. Thus, the main challenge in potato frying is to reduce the formation of the undesirable characteristics, without compromising the sensorial attributes. High Pressure Processing (HPP) technology has been used to accelerate infusion processes, as well as to modify the potato starch, enzymes, texture and physiological processes, and thereby this work aimed to evaluate the potentiality of HPP on modification of physico-chemical properties of raw potato tubers, and of sensory, nutritional and physico-chemical properties of the respective fried potatoes, as well as on asparaginase infusion into raw potato sticks, and consequently on reduction of acrylamide levels in fried potatoes. Whole potato tubers (peeled and unpeeled, packaged in water or under vacuum) subjected to 100-500 MPa for 2.5 min exhibited a decrease of up to 42% in their firmness, and an increase of up to ~12-fold in water exudation of peeled potatoes, due to the changes on texture and cell permeability caused by HPP. Raw potato sticks treated by HPP (200-600 MPa, 2.5 and 10 min) or infused with asparaginase by HPP (100-400 MPa, 5 min) exhibited reductions in firmness (up to 35%), stiffness (up to 38%), and energy for cutting (up to 47%); the roughness of potato surface was also reduced and moisture content slightly reduced; and the concentration of soluble solids/sugars in the exterior water increased. Also, HPP induced starch gelatinization, followed by starch retrogradation at 600 MPa. Due to changes induced by HPP on raw potatoes, HPP pre-treated fried potatoes exhibited higher weight loss after frying, slight lower moisture content, higher hardness (crispness), and a lighter colour. Lipid content, lipid profile and acrylamide levels were quality parameters that were not affected by HPP. When asparaginase was added, acrylamide levels of fried potatoes pre-treated at 100-400 MPa reduced of 26-47%, while with asparaginase alone (without HPP) there was no reduction. Thus, this combined asparaginase and HPP treatment could be a novel strategy for acrylamide mitigation in fried potatoes. In sum, HPP showed to affect the quality of potato tubers at the textural, physical and chemical level, and was efficient on the asparaginase infusion into raw potato sticks. Therefore, it may be used as a pre-treatment for the production of fried potatoes with different/better sensorial, textural and nutritional properties, as well as to improve energetically some industrial processes (for instance, the cutting process and frying time).