Development of a new protocol for freeze-drying preservation of Pseudoalteromonas nigrifaciens and its protective effect on other marine bacteria

Background: Freeze-drying is known as one of the best methods to preserve bacterial strains. Protectant is the key factor affecting the survival rate of freeze-dried strains. In addition, salinity, bacterial suspension concentration, drying time, and other factors can also affect the survival rate of strains to varying degrees. At present, there are relatively few studies on freeze-drying preservation of marine bacteria. In the present study, we performed the freeze-drying protectant screening and optimized the preservation conditions for Pseudoalteromonas nigrifaciens, which is widely distributed in marine environment. The protective effects of the screened protectants were verified by 18 other marine bacterial strains. Results: The results indicated that the combination of 5.0% (w/v) lactose, 5.0% (w/v) mannitol, 5.0% (w/v) trehalose, 10.0% (w/v) skim milk powder, 0.5% (w/v) ascorbic acid and 0.5% (w/v) gelatin was the best choice for the preservation of P. nigrifaciens. The suggested salinity and concentration of initial cell suspension were 10 g/L NaCl and 1.0 × 109 CFU/mL, respectively. Furthermore, stationary-phase cells were the best choice for the freeze-drying process. The highest survival rate of P. nigrifaciens reached 52.8% when using 5­10% (w/v) skim milk as rehydration medium. Moreover, the other 18 marine strains belonging to Pseudoalteromonas, Vibrio, Photobacterium, Planomicrobium, Edwardsiella, Enterococcus, Bacillus, and Saccharomyces were freezedried under the abovementioned conditions. Their survival rates were 2.3­95.1%. Conclusion: Collectively, our results supported that the protectant mixture and parameters were beneficial for lyophilization of marine bacteria

Reducción de proteínas y glucosa por reacción de Maillard en leche con lactosa hidrolisada / Protein and glucose reduction by Maillard reaction in milk with hydrolyzed lactose

Se evaluó el efecto de la temperatura sobre la desnaturalización de proteínas y la reacción de Maillard en leche entera y descremada con lactosa hidrolizada. Las leches hidrolizadas se trataron térmicamente a 100, 110, 120 y 130 °C durante un período de 1 hora y se midió la concentración de glucosa, el grado de pardeamiento y la desnaturalización de proteínas. El grado de dorado en la leche entera varió de 14.4 (100 °C) a 42.6 (130 °C). Para la leche descremada fue de 20.2 (100 °C) a 38.0 (130 °C). La concentración de glucosa en leche entera (47% p/v) y en leche descremada (41% p/v) después del tratamiento térmico (130 °C) mostró una reducción significativa en relación con el control (25 °C). El efecto de la temperatura en la desnaturalización de proteínas en leche entera y descremada en relación con el control (25 °C) fue del 100%. La leche tratada térmicamente con lactosa hidrolizada promovió la desnaturalización de proteínas con un aumento del pardeamiento característico de la reacción de Maillard, lo que afectó la calidad nutricional.

The effect of temperature in protein denaturation and Maillard reaction in whole and skim milk with hydrolyzed lactose was evaluated. Hydrolyzed milk was thermally treated at 100, 110, 120 and 130 °C over a period of 1 hour and glucose concentration, browning degree and protein denaturation were measured. The browning degree in whole milk varied from 14.42 (100 °C) to 42.63 (130 °C) and 20.21 (100 °C) to 38.03 (130 °C) in skim milk. Glucose concentration in whole milk (47% - w/v) and skim milk (41% - w/v) after heat treatment (130 °C) showed a significant reduction in relation to the control (25 °C). The temperature effect in protein denaturation in whole and skim milk in relation to the control (25 °C) was 100%. Thermally treated milk with hydrolyzed lactose promoted protein denaturation with increasing browning characteristic of the Maillard reaction, thus affecting the nutritional quality.

Influência de diferentes concentrações de enzima lactase sobre a hidrólise da lactose em leite pasteurizado e seus aspectos físico-químicos / Influence of different concentrations of lactase enzymes on a lactose hydrolysis in pasteurized milk and their physico-chemical aspects

A lactose é o carboidrato predominante no leite e responsável por diversas reações importantes no processamento de derivados lácteos. Contudo, também é responsável pelo desconforto trazido às pessoas intolerantes à este açúcar. A indústria vem se aprimorando para retirar ou reduzir a lactose dos produtos lácteos. Este trabalho objetivou testar o método de hidrólise para reduzir o teor de lactose no leite de vaca pasteurizado utilizando três concentrações de enzima diferentes e observar as propriedades físico-químicas decorrentes do processo. Os três tratamentos foram submetidos a 30ºC por tempo suficiente para que a crioscopia de cada um estabilizasse. Os resultados demonstraram que a enzima testada foi eficaz para reduzir o teor de lactose no leite em até aproximadamente 93%, mas nenhum dos tratamentos se enquadraria na legislação vigente como “zero lactose”. As propriedades físico-químicas mantiveram-se dentro dos limites da legislação para leite pasteurizado.

Efficacy of Lactose-free Milk in Korean Adults with Lactose Intolerance / 대한소화기학회지

BACKGROUND/AIMS: Lactose-free milk (LFM) is available for nutrient supply for those with lactose intolerance (LI). However, there are no consistent results of the efficacy of LFM in LI subjects. We aimed to examine the changes of gastrointestinal (GI) symptoms and hydrogen breath test (HBT) values after ingestion of lactose contained milk (LCM) vs. LFM. METHODS: From May 2015 to September 2015, thirty-five healthy adults with history of LCM-induced GI symptoms were recruited at a tertiary hospital. For the diagnosis of LI, HBT with LCM 550 mL (lactose 25 g) was performed every 20 minutes for 3 hours. The test was defined as "positive" when H2 peak exceeded 20 ppm above baseline values (DeltaH2>20 ppm). When the subjects are diagnosed as LI, the second HBT using LFM 550 mL (lactose 0 g) was performed 7 days later. Subjects were asked to complete a questionnaire about the occurrence and severity of GI symptoms. RESULTS: Among a total of 35 subjects, 31 were diagnosed with LI at first visit, and their LCM-related symptoms were abdominal pain (98.6%), borborygmus (96.8%), diarrhea (90.3%), and flatus (87.1%). The DeltaH2 value in subjects taking LCM (103.7+/-66.3 ppm) significantly decreased to 6.3+/-4.9 ppm after ingesting LFM (p<0.0001). There were also significant reduction in total symptom scores and the severity of each symptom when LCM was changed to LFM (p<0.0001). CONCLUSIONS: This is the first report that LFM reduce LCM-related GI symptoms and H2 production in Korean adults. LFM can be an effective alternative for LCM in adults with LI.

Inhibitory effect of lotus seedpod oligomeric procyanidins on advanced glycation end product formation in a lactose-lysine model system

Background Industrial food processing induces protein glycation modifications and toxic advanced glycation end products (AGEs) which affect human health. Therefore, it is of interest to monitor AGEs in food processing. The present study was carried out to investigate the influence of lotus seedpod oligomeric procyanidin (LSOPC) concentrations, solution pH value and metal ions on AGE formation by heat treatment of lactose-lysine model solutions. Ne-(carboxymethyl) lysine (CML), as one of the common AGEs was also determined by HPLC-MS/MS in this experiment. Results The results showed that LSOPC can inhibit the formation of AGEs effectively at higher concentrations, lower temperature, and it can reverse the promotion function of metal ions because of its high inhibition activity. Also, LSOPC can inhibit CML formation in the Maillard reaction as well. Conclusion These results indicated that LSOPC could be used as functional food ingredients to inhibit AGE formation.

Freezing and thawing effects on fat, protein, and lactose levels of human natural milk administered by gavage and continuous infusion / Efeito do congelamento e descongelamento nos níveis de gordura, proteína e lactose do leite humano natural administrados por gavagem e infusão contínua

OBJECTIVES: to analyze the changes in human milk macronutrients: fat, protein, and lactose in natural human milk (raw), frozen and thawed, after administration simulation by gavage and continuous infusion. METHOD: an experimental study was performed with 34 human milk samples. The infrared spectrophotometry using the infrared analysis equipment MilkoScan Minor(r) (Foss, Denmark) equipment was used to analyze the macronutrients in human milk during the study phases. The analyses were performed in natural (raw) samples and after freezing and fast thawing following two steps: gavage and continuous infusion. The non-parametric Wilcoxon test for paired samples was used for the statistical analysis. RESULTS: the fat content was significantly reduced after administration by continuous infusion (p < 0.001) during administration of both raw and thawed samples. No changes in protein and lactose content were observed between the two forms of infusion. However, the thawing process significantly increased the levels of lactose and milk protein. CONCLUSION: the route of administration by continuous infusion showed the greatest influence on fat loss among all the processes required for human milk administration. .

OBJETIVO: analisar as alterações dos macronutrientes gordura, proteína e lactose no leite humano natural, congelado e descongelado, após a simulação da administração da dieta por gavagem e infusão contínua. MÉTODO: foi conduzido um estudo experimental com 34 amostras de leite humano. Foi utilizada a técnica da espectofotometria infravermelha (Milko Scan Minor(r)) para analisar os macronutrientes do leite humano nas etapas do estudo. As amostras foram analisadas na forma natural (crua) e após congelamento e descongelamento rápido nas duas formas de infusão: gavagem e infusão contínua. Foi usado o teste não paramétrico de Wilcoxon para amostras pareadas na análise estatística. RESULTADO: a gordura apresentou redução significativa após administração por infusão contínua (p < 0,001), tanto durante administração na forma natural quanto na forma descongelada. Não houve alteração da proteína e lactose segundo forma de infusão no leite descongelado e no leite in natura. O processo de descongelamento aumentou significativamente os níveis de lactose e de proteína do leite. CONCLUSÃO: a via de administração por infusão contínua foi o procedimento que mais influenciou na perda de gordura, dentre todos os processos necessários para administração do leite humano. .

Contol de claidad de la leche materna / Quality control of maternal milk

Se presenta un estudio transversal realizado en Montevideo, República Oriental del Uruguay, del valor calórico de la leche materna, proveniente de 80 muestras de 77 mujeres. El cálculo del valor calórico se estimó en base al contenido de proteinas, lactosa y grasas. las dosificaciones fueron realizas por un procesamineto automatizado (Milko Scan 1.33), previamente calibrado por el método químico. El valor calórico de la leche fue de 68 Kcal/100 ml+- 17 (2 desvios estándar, DE). La concentración de proteinas fue mayor en el primer mes, luego disminuyó y permaneció constante, el valor promedio fue de 1,63 g/100 ml +-0,41. La lactosa presentó muy poca variación, el promedio fue 6,2 g/100 ml +- 0,61. Las grasas fueron las que tuvieron mayor variabilidad, con una tendencia significativa al aumento (0,27 g/100ml+-1,92. Se encontró una buena correlación (r=0,98) entre la concentración de grasas y el valor calórico de leche, ya que la concentración de proteínas y lactosa permanece constante. No se encontró ninguna correlación entre las variables antropométricas maternas y la concentración de proteínas, grasa y lactosa. Se concluyó que en la muestra estudiada el valor calórico promedio de la leche materna no difiere de lo descrito en la literatura, pero tiene una variabilidad considerable+- 12 porciento y ésta se debe especialmente a las grasas.

Properties of crude beta-galactosidase of Mucor hemiclonus and its application in lactose hydrolysis of some dairy by-products

Biochemical studies on the properties of acetone precipitated extracellular beta-galactosidase of M. humicolus indicated that the enzyme is notably thermostable expressing maximum activity at 60° and pH 3.0. The reaction progress with time was linear up to 30 minutes of incubation. The enzyme could effectively hydrolyze lactose present in some dairy by-products. Thus upon using enzyme level of 0.9 unit/ml the enzyme could hydrolyze 28.8%, 32.4%, 62.4%, 18.2% and 43.1% of lactose present in milk, whey, 1: 1 diluted whey, whey permeate and 1: 1 diluted whey permeate respectively, after 8 hr at 30°. At 40° and at the same enzyme level the percentage of lactose hydrolyzed reached 60.0%, 63.6%, 69.6% and 70.0% in whey permeate, whey, diluted permeate and diluted whey respectively. At the same temp. [40°] and by increasing enzyme concen. to 1.8 unit/ml, the lactose hydrolysis reached 64.4%, 84.0%, 77.0% and 86.8% of lactose present in the four substrates respectively. The results are discussed in the light of the application feasibility of this enzyme