Patulin contamination of hard apple cider by Paecilomyces niveus and other postharvest apple pathogens: Assessing risk factors

Hard apple cider is considered to be a low-risk product for food spoilage and mycotoxin contamination due to its alcoholic nature and associated food sanitation measures. However, the thermotolerant mycotoxin-producing fungus Paecilomyces niveus may pose a significant threat to hard cider producers. P. niveus is known to infect apples (Malus xdomestica), and previous research indicates that it can survive thermal processing and contaminate finished apple juice with the mycotoxin patulin. To determine if hard apple cider is susceptible to a similar spoilage phenomenon, cider apples were infected with P. niveus or one of three patulin-producing Penicillium species and the infected fruits underwent benchtop fermentation. Cider was made with lab inoculated Dabinett and Medaille d'Or apple cultivars, and patulin was quantified before and after fermentation. Results show that all four fungi can infect cider apples and produce patulin, some of which is lost during fermentation. Only P. niveus was able to actively grow throughout the fermentation process. To determine if apple cider can be treated to hinder P. niveus growth, selected industry-grade sanitation measures were tested, including chemical preservatives and pasteurization. High concentrations of preservatives inhibited P. niveus growth, but apple cider flash pasteurization was not found to significantly impact spore germination. This study confirms that hard apple cider is susceptible to fungal-mediated spoilage and patulin contamination. P. niveus is an important concern for hard apple cider producers due to its demonstrated thermotolerance, survival in fermentative environments, and resistance to sanitation measures.

Comparison of Common Analytical Methods for the Quantification of Total Polyphenols and Flavanols in Fruit Juices and Ciders

Multiple analytical methods are used for quantification of total polyphenols and total flavanols in fruit juices and beverages. Four methods were evaluated in this study: Folin-Ciocalteu (F-C), Lowenthal permanganate (L-P), 4-dimethylaminocinnamaldehyde (DMAC), and the bovine serum albumin (BSA) precipitation method. Method validation parameters, including working range, limit of detection, limit of quantitation, precision (repeatability), accuracy, and specificity, were assessed and compared. The F-C method was not specific to polyphenols, and the L-P method had the widest working range but lacked accuracy. The DMAC method was the most specific to flavanols, and the BSA method was not suitable for quantification of smaller flavanols, such as catechin and epicatechin. Quantitative performance was evaluated using commercial fruit juice samples (n = 14), apple juice samples of different cultivars (n = 22), and commercial ciders (n = 17). In general, the L-P titration method and DMAC method resulted in higher quantitative values than the F-C method and BSA precipitation method, respectively. However, ratios of results obtained by the L-P and F-C method ranged from 1 to 28, and ratios of results obtained by the DMAC and BSA precipitation method ranged from <1 to 280. This tremendous variation is likely due to variation in polyphenol composition and sample matrix. This information provides perspective for comparison of results obtained through these different methods, and a basis for choosing the most appropriate analytical method for quantification of polyphenols to address a specific research question when working with commercial fruit juice, apple juice from different apple cultivars, and commercial ciders. PRACTICAL APPLICATION: This study compared results obtained when four common polyphenol quantification methods were applied to a diverse selection of fruit juices and beverages with distinct polyphenol composition and sample matrix. The matrix and polyphenol composition of the samples significantly influenced the results. Our findings can help manufacturers of fruit-based products choose the most appropriate analytical method for polyphenol quantification as part of a quality assurance program or to convey information on dietary polyphenol content to consumers. An assessment of analytical method validation parameters is provided for each of the four methods, which will help users of these methods to understand their limitations.

Free amino nitrogen concentration correlates to total yeast assimilable nitrogen concentration in apple juice

Yeast assimilable nitrogen (YAN) is essential for yeast growth and metabolism during apple (Malus x domestica Borkh.) cider fermentation. YAN concentration and composition can impact cider fermentation kinetics and the formation of volatile aroma compounds by yeast. The YAN concentration and composition of apples grown in Virginia, USA over the course of two seasons was determined through analysis of both free amino nitrogen (FAN) and ammonium ion concentration. FAN was the largest fraction of YAN, with a mean value of 51 mg N L^-1 FAN compared to 9 mg N L^-1 ammonium. Observed YAN values ranged from nine to 249 mg N L^-1, with a mean value of 59 mg N L^-1. Ninety-four percent of all samples analyzed in this study contained <140 mg N L^-1 YAN, a concentration generally considered the minimum level needed in grape-based wines for yeast to fully utilize all of the fermentable sugars. FAN concentration was correlated with total YAN concentration, but ammonium concentration was not. Likewise, there was no correlation between FAN and ammonium concentration.

The interactive effect of fungicide residues and yeast assimilable nitrogen on fermentation kinetics and hydrogen sulfide production during cider fermentation

BACKGROUND

Fungicide residues on fruit may adversely affect yeast during cider fermentation, leading to sluggish or stuck fermentation or the production of hydrogen sulfide (H₂ S), which is an undesirable aroma compound. This phenomenon has been studied in grape fermentation but not in apple fermentation. Low nitrogen availability, which is characteristic of apples, may further exacerbate the effects of fungicides on yeast during fermentation. The present study explored the effects of three fungicides: elemental sulfur (S⁰ ) (known to result in increased H₂ S in wine); fenbuconazole (used in orchards but not vineyards); and fludioxonil (used in post-harvest storage of apples).

RESULTS

Only S⁰ led to increased H₂ S production. Fenbuconazole (≥0.2 mg L^-1 ) resulted in a decreased fermentation rate and increased residual sugar. An interactive effect of yeast assimilable nitrogen (YAN) concentration and fenbuconazole was observed such that increasing the YAN concentration alleviated the negative effects of fenbuconazole on fermentation kinetics.

CONCLUSION

Cidermakers should be aware that residual fenbuconazole (as low as 0.2 mg L^-1 ) in apple juice may lead to stuck fermentation, especially when the YAN concentration is below 250 mg L^-1 . These results indicate that fermentation problems attributed to low YAN may be caused or exacerbated by additional factors such as fungicide residues, which have a greater impact on fermentation performance under low YAN conditions. © 2016 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Characterization of the polyphenol composition of 20 cultivars of cider, processing, and dessert apples (Malus × domestica Borkh.) grown in Virginia

Polyphenols and maturity parameters were determined in 20 apple cultivars with potential for hard cider production grown in Virginia, U.S.A. Concentrations of five classes of polyphenols were significantly different across cultivar for both peel and flesh. Total polyphenol concentration ranged from 0.9 μg/g wwb in flesh of Newtown Pippin to 453 μg/g wwb in peel of Red Delicious. Harrison, Granny Smith, Rome, Winesap, and Black Twig cultivars contained the highest concentration of total flavan-3-ols in flesh, indicating potential to impart desired astringency and bitterness to cider under processing conditions where extraction of polyphenols from peel is minimal. These results can inform selection of fruit juice, extracts, and byproducts for investigations of bioactivity and bioavailability of polyphenols, and provide baseline data for horticultural and processing research supporting the growing hard cider industry in Virginia. Based on these data, cultivars Harrison, Granny Smith, Rome, Winesap, and Black Twig show high potential for cider production in Virginia.

Non-dipping circadian blood pressure and renal impairment are associated with increased mortality in diabetes mellitus

AIMS

To assess the relevance of circadian blood pressure variation to future morbidity and mortality in patients with diabetes mellitus.

METHODS

A retrospective descriptive 4 year follow-up study of data collected after ambulatory blood pressure monitoring in a clinic setting.

RESULTS

Seventy-five patients (46 male; 29 female) of whom 41 % had Type 1 diabetes and 59% Type 2 were followed up for a median of 42 months (11-56). The median creatinine for the whole group at baseline was 101 (56-501) micromol/l. The median circadian blood pressures for the total study population were 147 (110-194)/87 (66-109) mmHg during daytime and 132 (86-190)/77 (50-122) mmHg during night-time. Half of the patients exhibited a fall in night-time pressures to 10% lower than daytime pressures (dippers). Dippers were younger, 47 (32-75) years, than non-dippers, 57 (35-79) years, P = 0.03. Over time, dippers had a lower mortality than non-dippers, with 8% deaths in the cohort of dippers, 26% deaths in the cohort of non-dippers, P = 0.04. Cox regression analysis revealed significant contributions from age, duration of diabetes and baseline renal function to subsequent mortality in non-dippers. Analysing current degree of renal impairment and original dipper status together revealed that, of those patients whose creatinine remained normal, 7% of patients whose blood pressure dipped had subsequently died and 10% of non-dipping patients had died; of those patients whose creatinine unequivocally rose, 10% of dipping patients had died and 42% of non-dipping patients had died, P = 0.03

CONCLUSIONS

Loss of circadian variation in blood pressure is associated with an increased mortality rate, regardless of diabetes type. The combination of non-dipping and subsequent renal impairment leads to the highest mortality rate. The study suggests a role for ambulatory blood pressure monitoring in day-to-day clinical practice to select patients with nephropathy who are at greatest risk, in an effort to alter outcome.

An assessment of blood pressure measurement in a diabetic clinic using random-zero, semi-automated, and 24-hour monitoring

We have undertaken a randomized, observer-blinded comparison of three different methods of assessing blood pressure in 40 outpatients with hypertension complicating diabetes mellitus: the Hawksley random zero sphygmomanometer (RZS) by two observers using a dual headed stethoscope; the semi-automated Dinamap monitor, and 24-h ambulatory blood pressure monitoring (ABPM) using a Spacelabs 90207. The techniques were compared by plotting the difference against average of readings obtained by combinations of two techniques (RZS observer 1 vs 2; RZS (mean observer 1 and 2) vs Dinamap; RZS (mean observer 1 and 2) vs daytime ABPM; and Dinamap vs daytime ABPM). There was good agreement of readings with RZS, observers 1 and 2 and RZS with Dinamap and daytime ABPM. When the three methods were used to classify blood pressure control according to BDA criteria, it was found that they produced equivalent results and although mean systolic pressures appeared lower with ABPM this did not reach statistical significance. Overall control of systolic blood pressure was classified as unsatisfactory in 82% of patients, diastolic blood pressure was unsatisfactory in 55%. Fifty-five percent were determined to be nocturnal 'non-dippers' by ABPM. They were older: median age 62.9 (range 35.9-83.5) years compared to 48.2 (32.4-70.0) years for 'dippers' (p<0.05). Thirteen of the 18 patients who did dip overnight had creatinines within the normal laboratory range, whereas only 6 of 22 'non-dippers' had normal creatinines (median 91 (56-768) micromol l(-1) for 'dippers' vs 166 (76-479) micromol l(-1) for 'non-dippers', p < 0.001). Nineteen of the 29 males studied were 'non-dippers' compared with only 4 out of 11 females (p < 0.001). There was no association between dipper status, duration or type of diabetes or presence of proteinuria.

A community survey of diabetes in the elderly

All 98 elderly patients who were known to have diabetes on the lists of two inner-city general practices were interviewed and examined in their own homes. They were characterized in terms of their prevalence of vascular complications, metabolic control, perceived health (measured by the Nottingham Health Profile), frequency of hospital and general practice contacts and use of domiciliary 'support services' and compared to 98 control subjects with an identical age/gender distribution. Mean haemoglobin A1 in the diabetic patients was 9.9 +/- 2.5%, few of them had suffered severe hyperglycaemia (10%) or hypoglycaemia (5%) and they were little more obese than controls (mean body mass index 26.2 +/- 4.2 vs 24.6 +/- 4.1 kg m-2; 95% confidence interval for the difference 0.4-2.8; p < 0.01). All complications were more prevalent in diabetic patients and the difference was statistically significant for visual impairment, strokes, impaired mental test scores, absent vibration sense, and absent leg pulses. Cataract was more common than retinopathy as a cause of visual disability. Diabetic patients perceived their health to be much worse than controls and were more often depressed. No measure of perceived health correlated with haemoglobin A1. We conclude that care of the diabetic elderly should not be too narrowly focused on 'metabolic' goals.

Double-blind evaluation of efficacy and tolerability of metformin in NIDDM

OBJECTIVE

To test the efficacy and tolerability of metformin.

RESEARCH DESIGN AND METHODS

An 8-mo double-blind placebo-controlled parallel-group trial was performed at University hospital diabetic clinics on 60 patients with non-insulin-dependent diabetes mellitus (NIDDM) treated by diet alone. Metformin was administered and built up to a maximum dosage of 1 g three times daily.

RESULTS

Mean HbA1 fell from 11.7 +/- 0.4 to 10.3 +/- 0.4% (means +/- SE) on metformin but rose from 11.8 +/- 0.4 to 13.3 +/- 0.4% on placebo (P less than 0.001). Final mean fasting blood glucose was 5.1 mM lower with metformin than placebo (P less than 0.001). No other biochemical variable differed significantly, and weight did not change. A favorable glycemic response was not restricted to the obese. The mean final dosage of metformin was 1.7 +/- 0.1 g and was well tolerated.

CONCLUSIONS

Metformin achieved a 23% lower mean HbA1 than placebo without weight gain or significant unwanted effects.