Conservação de morangos congelados enriquecidos com Saccharomyces boulardii utilizando revestimento à base de gelatina comercial.

Abstract

Freezing is considered one of the easiest ways to preserve the quality of food, however the preservation of strawberries by this technique is very difficult to perform, due to the loss of anthocyanins; oxidation of phenolic compounds by the action of polyphenoloxidase, oxidation of vitamin C; in addition to the loss of exudate and texture due to the damage caused by the ice crystals. An alternative to minimize such effects is the use of edible coatings, which in addition to reducing the loss of exudate and oxidation reactions, can be used as carriers of functional compounds. Thus, the objective of the study is to evaluate the conservation of frozen strawberries using commercial gelatin as a coating and carrier of the probiotic yeast, Saccharomyces boulardii. The strawberries were selected, washed and sanitized in sodium hypochlorite solution (200 mg L-1), after which they were submitted to the different treatments: 1 - Control 1 (strawberry stored at –18 ºC); 2 - control 2 (strawberry stored at –80 ºC); 3 - strawberries added with citric acid (1.0% w / v), calcium chloride (1.0% w /v) and Saccharomyces boulardii CNCM I-745 stored at –18 ºC; 4 - strawberries with gelatin (5.0% w/v), citric acid (1.0% w/v), calcium chloride (1.0% w/v), glycerol (1.0% w/v) ) and Saccharomyces boulardii CNCM I-745 stored at –18 ºC. The strawberries were packed in high density polyethylene bags and stored for 90 days under freezing. Loss of exudate, soluble solids, pH, titratable acidity, color, firmness, ascorbic acid, total phenolic compounds, monomeric anthocyanins, antioxidant activity, polyphenoloxidase activity and viability of Saccharomyces boulardii were evaluated. The use of gelatin coating on strawberries minimized the effects of freezing and promoted the protection of Saccharomyces boulardii, obtaining up to 60 days of storage the minimum viable concentration of the microorganism to exercise the functional property and reduce the loss of exudate. In addition, the gelatin coating added with citric acid and calcium chloride together with freezing at –18 ºC reduced metabolic reactions and exerted a protective effect on bioactive compounds, making it possible to use them instead of deep freezing. On the other hand, in the absence of gelatin, Saccharomyces boulardii had a negative influence on the physical-chemical parameters, in addition to showing less viability.