Selection of Antarctic yeasts as gray mold biocontrol agents in strawberry.

The postharvest disease popularly known as gray mold is considered one of the most limiting factors strawberry fruit production. The most effective way to control this disease is still the use of chemical fungicides. However, other alternative sources of control are being explored. Among these, psychrophilic yeasts adapted to extreme conditions, such as those found in the Antarctic region, may have great potential for use as biocontrol agents. Thus, the present study aimed to select psychrotolerant yeasts obtained from Antarctic region and to evaluate their potential for biocontrol under gray mold, caused by Botrytis cinerea in strawberries stored at low temperature. For this, 20 potential antagonist yeasts were evaluated in vitro (thermotolerance and enzymatic) assays. Debaryomyces hansenii, Rhodotorula mucilaginosa and Dioszegia hungarica were selected for growing in strawberry juice. However, only D. hansenii was selected for in vivo studies and showed a reduction in the incidence of gray mold by 82% for the tests performed on injury and 86% for the tests on non-injured fruits treated by immersion bath. Thus, demonstrating that the selection of this cold-adapted Antarctic yeast can be a promising strategy as a biocontrol agent used to curb the development of gray mold in strawberry fruits.

Development of Araticum (Annona crassiflora Mart.) jams: evaluation of physical, microbiological, and sensorial stability in different packages.

Araticum is an exotic fruit with unique sensory features and also high nutritional value characteristics. This study aimed to develop araticum jams with substitution of commercial pectin for passion fruit albedo, as well as to evaluate its physical, microbiological and sensorial stability during storage in polyethylene and polypropylene packages. Samples were analyzed at 25 and 35 °C for 130 days. During the storage the values of pH (3.5-4.9), titratable acidity (0.27-0.62%), color (L* 20.56-28.49, a* 1.32-7.03, and b* 1.32-9.29), chroma (1.86-11.65), hue (0.60-1.03), soluble solids (68-79.70 ºBrix), reducing sugars (12.60-60.30%), non-reducing sugars (6.22-56.19%), total sugars (55.30-96.30%), and carotenoids (0.21-1.27 mg.100 g-1) varied. The indicated shelf life was approximately 117 and 65 days for jams in polypropylene package, and 112 and 63 days for those kept in the polyethylene package, when the temperature of storage was 25 and 35 ºC, respectively. Araticum fruit is a good source for jams, that can contribute to the increased insertion of foods of better nutritional value in the consumer market.

Chemical Composition and Antimicrobial Potential of Palm Leaf Extracts from Babaçu (Attalea speciosa), Buriti (Mauritia flexuosa), and Macaúba (Acrocomia aculeata).

Babaçu (A. speciosa), Buriti (M. flexuosa), and Macaúba (A. aculeata) are palm trees typical of the ecotone area between Cerrado and the Amazon rainforest. The purpose of this study was to evaluate the antimicrobial potential of the extracts prepared from the leaves of those palms as well as determine their chemical compositions. The ethanol extracts were prepared in a Soxhlet apparatus and tested by disk diffusion and agar dilution technique against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, Candida albicans, and Candida parapsilosis. However, there was no significant activity at concentrations of 25, 50, and 100 mg·Ml(-1). Moreover, the phytochemical analysis revealed the presence of tannins, flavonoids, catechins, steroids, triterpenes, and saponins. Gas chromatography (GC/MS) analysis also identified organic acids, such as capric (decanoic) acid, lauric (dodecanoic) acid, myristic (tetradecanoic) acid, phthalic (1,2-benzenedicarboxylic) acid, palmitic (hexadecanoic) acid, stearic (octadecanoic) acid, linoleic (9,12-octadecadienoic) acid (omega-6), linolenic (octadecatrienoic) acid (omega-3), and the terpenes citronellol and phytol. Based on the chemical composition in the palm leaf extracts, the palms have the potential to be useful in the food, cosmetic, and pharmaceutical industries.

Use of Probiotics to Control Aflatoxin Production in Peanut Grains.

Probiotic microorganisms (Saccharomyces cerevisiae var. boulardii, S. cerevisiae UFMG 905, and Lactobacillus delbrueckii UFV H2b20) were evaluated as biological control agents to reduce aflatoxin and spore production by Aspergillus parasiticus IMI 242695 in peanut. Suspensions containing the probiotics alone or in combinations were tested by sprinkling on the grains followed by incubation for seven days at 25°C. All probiotic microorganisms, in live and inactivated forms, significantly reduced A. parasiticus sporulation, but the best results were obtained with live cells. The presence of probiotics also altered the color of A. parasiticus colonies but not the spore morphology. Reduction in aflatoxin production of 72.8 and 65.8% was observed for S. boulardii and S. cerevisiae, respectively, when inoculated alone. When inoculated in pairs, all probiotic combinations reduced significantly aflatoxin production, and the best reduction was obtained with S. boulardii plus L. delbrueckii (96.1%) followed by S. boulardii plus S. cerevisiae and L. delbrueckii plus S. cerevisiae (71.1 and 66.7%, resp.). All probiotics remained viable in high numbers on the grains even after 300 days. The results of the present study suggest a different use of probiotics as an alternative treatment to prevent aflatoxin production in peanut grains.