title: Vitamin C, total phenolics and antioxidative activity in tip-cut green beans (Phaseolus vulgaris) and swede rods (Brassica napus var. napobrassica) processed by methods used in catering.
abstract: BACKGROUND
  Retention of nutrients in vegetables during blanching/freezing, cooking and warm-holding is crucial in the preparation of both standard and therapeutic diets. In the present study, conventional cooking in water, and cooking by pouch technology (boil-in-bag, sous vide) were compared in their ability to retain vitamin C, total phenolics and antioxidative activity (DPPH and FRAP) in industrially blanched/frozen tip-cut green beans and swede rods.
  
  
  RESULTS
  After conventional cooking, 50.4% total ascorbic acid, 76.7% total phenolics, 55.7% DPPH and 59.0% FRAP were recovered in the drained beans. After boil-in-bag cooking, significantly (P < 0.05) higher recoveries were obtained, i.e. 80.5% total ascorbic acid, 89.2% total phenolics, 94.8% DPPH and 92.9% FRAP. Recoveries after sous vide cooking were comparable to those of boil-in-bag cooking. By conventional cooking, 13.5-42.8% of the nutrients leaked into the cooking water; by sous vide about 10% leaked to the exuded liquid, while no leakage occurred by boil-in-bag cooking. Warm-holding beans after cooking reduced recoveries in all components. Recoveries in swede rods were comparable but overall slightly lower.
  
  
  CONCLUSIONS
  Industrially blanched/frozen vegetables should preferably be cooked by pouch technology, rather than conventional cooking in water. Including cooking water or exuded liquid into the final dish will increase the level of nutrients in a meal. Warm-holding of vegetables after cooking should be avoided.
authors.affiliation: Nofima Mat AS, Osloveien 1, NO-1430 Aas, Norway. pernille.baardseth@nofima.no
authors.forename: Pernille
authors.initials: P
authors.lastname: Baardseth
authors.forename: Frøydis
authors.initials: F
authors.lastname: Bjerke
authors.forename: Berit K
authors.initials: BK
authors.lastname: Martinsen
authors.forename: Grete
authors.initials: G
authors.lastname: Skrede
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D001205:Ascorbic Acid / Q000032:analysis*; D029688:Brassica napus / Q000737:chemistry*; D003296:Cooking / Q000379:methods*; D005419:Flavonoids / Q000032:analysis*; D005638:Fruit / Q000737:chemistry; D006358:Hot Temperature; D009753:Nutritive Value; D027805:Phaseolus / Q000737:chemistry*; D010636:Phenols / Q000032:analysis*; D018517:Plant Roots / Q000737:chemistry; D059808:Polyphenols; D014675:Vegetables / Q000737:chemistry*; D014867:Water
chemical_list: D000975:Antioxidants; D005419:Flavonoids; D010636:Phenols; D059808:Polyphenols; D014867:Water; D001205:Ascorbic Acid