Effect of ultra high-pressure homogenisation on natural-occurring micro-organisms in bovine milk

Abstract This study aimed to evaluate the effects of ultra high-pressure homogenisation (UHPH) on natural-occurring micro-organisms in bovine milk and compare the effects of heat and UHPH treatments. Whole raw milk was standardised at 3.5% and was processed using a Stansted High Pressure Homogeniser (model FPG11300, Stansted Fluid Power Ltd., Essex, UK). The microbiological quality of raw, high pasteurized (90ºC, 15 s) and pressure treated (200 and 300 MPa at inlet temperatures of 30 and 40ºC) milks was studied by enumerating total bacteria, psychrotrophic bacteria, coliforms, lactococci, lactobacilli and enterococci. UHPH treatments were as efficient (99.99%) as high-pasteurization treatment in reducing the total bacterial population, reaching important reductions (3-4 log cfu/ml). Lactococci count behaviour was similar to that of total bacteria count, reaching the same reductions. Psychrotrophic bacteria counts were not detected in high-pasteurized milks and were greatly reduced (~ 4 logs) in UHPH-treated milks. Coliforms, lactobacilli and enterococci were completed destroyed by both UHPH and heat treatments

Use of Ultra High Pressure Homogenization to sterilize grape must

Ultra-High Pressure Homogenization Sterilization (UHPHS) allows the sterilization of fluid foods at low temperatures or even in refrigeration. UHPHS is a continuous technique that allows to process 10,000 L/h with a single pump working at 300 MPa with an imbalance of 1 MPa (Ypsicon EP2409583). During the process, fluid temperature increases less than 5 ∘C. The technique is sensory gentle not affecting molecules formed by covalent bonds so aroma and pigments are unaltered. During the process of white musts, the complete elimination of yeasts, bacteria and spores can be achieved and the must may remain unfermented for several months-years if stored in amicrobic conditions. The technique is also effective in the destruction of polyphenol oxidase (PPO) enzymes. Final size particle is 100–300 nm allowing to increase the availability of yeast assimilable nitrogen and opens the opportunity to nano-encapsulate flavours. Destruction of PPOs and elimination of microorganisms help to reduce sulphites in wines. UHPHS facilitates the use of new biotechnologies such as the use of non-Saccharomyces yeasts and yeast-bacteria co-inoculations by enabling a better implantation of the starters in absence of competition with wild grape microorganisms

Effect of the inclusion of artichoke silage in the ration of lactating ewes on the properties of milk and cheese characteristics during ripening

[EN] The effect of including artichoke silage in the rations of dairy ewes on milk characteristics and biochemical changes of ripened cheeses was evaluated. Four groups of lactating ewes were fed rations containing 0, 10, 20, or 30% artichoke silage on a dry matter basis. Bulk milk samples were collected 3 times during the feeding period, and semi-hard cheeses were manufactured and sampled during ripening. Milk composition and cheese yield were not affected by diet. Inclusion of 20 and 30% artichoke silage reduced the firmness of the curds at a level only detected by the Gelograph (Gelograph-NT, Gel-Instrumente, Thalwil, Switzerland) probe. Inclusion of artichoke silage in ewes' diet decreased fat and total free fatty acids content of these cheeses and increased total free amino acids content. Despite the effect of diet on cheese ripening characteristics, the overall sensory scores for cheeses corresponding to artichoke silage diets were statistically higher than those for the control cheeses.The authors acknowledge the Ministerio de Ciencia y Teenologia for the financial support given to this investigation (INIA CAL 03-089). Diana P. Jaramillo acknowledges a research assistantship from the Centre Especial de Recerca Planta de Tecnologia dels Aliments (CERPTA).Jaramillo, DP.; Buffa, MN.; Rodríguez Garcia, M.; Pérez Baena, I.; Guamis, B.; Trujillo, AJ. (2010). Effect of the inclusion of artichoke silage in the ration of lactating ewes on the properties of milk and cheese characteristics during ripening. Journal of Dairy Science. 93(4):1412-1419. https://doi.org/10.3168/jds.2009-2740S1412141993

Inactivation of Staphylococcus aureus in raw milk cheese by combinations of high-pressure treatments and bacteriocin-producing lactic acid bacteria

Aims To investigate the combined effect of high-pressure treatments (HPT) and milk inoculation with bacteriocin-producing lactic acid bacteria (BP-LAB) on the survival of Staphylococcus aureus during ripening of raw milk cheese. Methods and Results Cheeses were manufactured from raw milk artificially contaminated with S. aureus at ca 5 log CFU ml-1, a commercial starter culture and one of seven strains of BP-LAB, added as adjuncts at 0.1%. HPT of cheeses were performed on days 2 or 50 at 300 MPa (10°C, 10 min) or 500 MPa (10°C, 5 min). On day 3, S. aureus counts were 6.46 log CFU g -1 in control cheese. Milk inoculation with different BP-LAB lowered S. aureus counts on day 3 when compared with control cheese by up to 0.46 log CFU g-1, HPT at 300 MPa on day 2 by 0.45 log CFU g-1 and HPT at 500 MPa on day 2 by 2.43 log CFU g-1. Combinations of BP-LAB with HPT at 300 and 500 MPa on day 2 lowered S. aureus counts on day 3 by up to 1.02 and 4.00 log CFU g-1 respectively. Conclusions The combined effect of milk inoculation with some of the BP-LAB tested and HPT of cheese on S. aureus inactivation was synergistic. Significance and Impact of the Study The combination of HPT at lower pressures with BP-LAB inoculation is a feasible system to improve cheese safety in case of deleterious effects on cheese quality caused by HPT at higher pressures