Nicoletta Pellegrini

A review on the beneficial aspects of food processing

The manuscript reviews beneficial aspects of food processing with main focus on cooking/heat treatment, including other food-processing techniques (e.g. fermentation). Benefits of thermal processing include inactivation of food-borne pathogens, natural toxins or other detrimental constituents, prolongation of shelf-life, improved digestibility and bioavailability of nutrients, improved palatability, taste, texture and flavour and enhanced functional properties, including augmented antioxidants and other defense reactivity or increased antimicrobial effectiveness. Thermal processing can bring some unintentional undesired consequences, such as losses of certain nutrients, formation of toxic compounds (acrylamide, furan or acrolein), or of compounds with negative effects on flavour perception, texture or colour. Heat treatment of foods needs to be optimized in order to promote beneficial effects and to counteract, to the best possible, undesired effects. This may be achieved more effectively/sustainably by consistent fine-tuning of technological processes rather than within ordinary household cooking conditions. The most important identified points for further study are information on processed foods to be considered in epidemiological work, databases should be built to estimate the intake of compounds from processed foods, translation of in-vitro results to in-vivo relevance for human health should be worked on, thermal and non-thermal processes should be optimized by application of kinetic principles.

Total antioxidant capacity of the diet is inversely and independently related to plasma concentration of high-sensitivity C-reactive protein in adult Italian subjects

Inflammation, a risk factor for cardiovascular disease, is associated with low plasma levels of antioxidant vitamins. In addition to vitamins, other antioxidants modulate the synthesis of inflammatory markers in vitro and contribute to the total antioxidant capacity (TAC) of a diet. However, the relationship between dietary TAC and markers of inflammation has never been evaluated in vivo. We investigated the relationship between dietary TAC and markers of systemic (high-sensitivity C-reactive protein (hs-CRP), leucocytes) and vascular (soluble intercellular cell adhesion molecule-1) inflammation in 243 non-diabetic subjects. General Linear Model (GLM) analysis showed a significant (P=0.005) inverse relationship between hs-CRP and quartiles of energy-adjusted dietary TAC, even when recognized modulating factors of inflammation, namely alcohol, fibre, vitamin C, alpha-tocopherol, beta-carotene, BMI, waist circumference, HDL-cholesterol, hypertension, insulin sensitivity and plasma beta-carotene, were included in the model as covariates (P=0.004). The relationship was stronger for subjects with hypertension (P=0.013 v. P=0.109 for normotensive individuals). Among dietary factors, TAC was significantly higher (5.3 (sd 3.0) v. 4.9 (sd 2.7) mmol Trolox/d; P=0.026) in subjects with low plasma hs-CRP (range: 0.0-4.1 mg/l) than in subjects with high plasma hs-CRP (range: 4.2-27.8 mg/l). We conclude that dietary TAC is inversely and independently correlated with plasma concentrations of hs-CRP and this could be one of the mechanisms explaining the protective effects against CVD of antioxidant-rich foods such as fruits, whole cereals and red wine. This could be of particular significance for subjects with high blood pressure.

High-level adherence to a Mediterranean diet beneficially impacts the gut microbiota and associated metabolome

Objectives Habitual diet plays a major role in shaping the composition of the gut microbiota, and also determines the repertoire of microbial metabolites that can influence the host. The typical Western diet corresponds to that of an omnivore; however, the Mediterranean diet (MD), common in the Western Mediterranean culture, is to date a nutritionally recommended dietary pattern that includes high-level consumption of cereals, fruit, vegetables and legumes. To investigate the potential benefits of the MD in this cross-sectional survey, we assessed the gut microbiota and metabolome in a cohort of Italian individuals in relation to their habitual diets. Design and results We retrieved daily dietary information and assessed gut microbiota and metabolome in 153 individuals habitually following omnivore, vegetarian or vegan diets. The majority of vegan and vegetarian subjects and 30% of omnivore subjects had a high adherence to the MD. We were able to stratify individuals according to both diet type and adherence to the MD on the basis of their dietary patterns and associated microbiota. We detected significant associations between consumption of vegetable-based diets and increased levels of faecal short-chain fatty acids, Prevotella and some fibre-degrading Firmicutes, whose role in human gut warrants further research. Conversely, we detected higher urinary trimethylamine oxide levels in individuals with lower adherence to the MD. Conclusions High-level consumption of plant foodstuffs consistent with an MD is associated with beneficial microbiome-related metabolomic profiles in subjects ostensibly consuming a Western diet. Trial registration number This study was registered at clinical trials.gov as NCT02118857.

Effect of different cooking methods on color, phytochemical concentration, and antioxidant capacity of raw and frozen Brassica vegetables.

This study evaluated the effect of common cooking practices (i.e., boiling, microwaving, and basket and oven steaming) on the phytochemical content (carotenoids, chlorophylls, glucosinolates, polyphenols, and ascorbic acid), total antioxidant capacity (TAC), and color changes of three generally consumed Brassica vegetables analyzed fresh and frozen. Among cooking procedures, boiling determined an increase of fresh broccoli carotenoids and fresh Brussels sprout polyphenols, whereas a decrease of almost all other phytochemicals in fresh and frozen samples was observed. Steaming procedures determined a release of polyphenols in both fresh and frozen samples. Microwaving was the best cooking method for maintaining the color of both fresh and frozen vegetables and obtaining a good retention of glucosinolates. During all cooking procedures, ascorbic acid was lost in great amount from all vegetables. Chlorophylls were more stable in frozen samples than in fresh ones, even though steaming methods were able to better preserve these compounds in fresh samples than others cooking methods applied. The overall results of this study demonstrate that fresh Brassica vegetables retain phytochemicals and TAC better than frozen samples.

Diagnosis of Non-Celiac Gluten Sensitivity (NCGS): The Salerno Experts' Criteria.

Non-Celiac Gluten Sensitivity (NCGS) is a syndrome characterized by intestinal and extra-intestinal symptoms related to the ingestion of gluten-containing food, in subjects that are not affected by either celiac disease or wheat allergy. Given the lack of a NCGS biomarker, there is the need for standardizing the procedure leading to the diagnosis confirmation. In this paper we report experts’ recommendations on how the diagnostic protocol should be performed for the confirmation of NCGS. A full diagnostic procedure should assess the clinical response to the gluten-free diet (GFD) and measure the effect of a gluten challenge after a period of treatment with the GFD. The clinical evaluation is performed using a self-administered instrument incorporating a modified version of the Gastrointestinal Symptom Rating Scale. The patient identifies one to three main symptoms that are quantitatively assessed using a Numerical Rating Scale with a score ranging from 1 to 10. The double-blind placebo-controlled gluten challenge (8 g/day) includes a one-week challenge followed by a one-week washout of strict GFD and by the crossover to the second one-week challenge. The vehicle should contain cooked, homogeneously distributed gluten. At least a variation of 30% of one to three main symptoms between the gluten and the placebo challenge should be detected to discriminate a positive from a negative result. The guidelines provided in this paper will help the clinician to reach a firm and positive diagnosis of NCGS and facilitate the comparisons of different studies, if adopted internationally.

Bioavailability and catabolism of green tea flavan-3-ols in humans

OBJECTIVE The aim of this study was to investigate green tea flavan-3-ol catabolism and plasma pharmacokinetic and urinary excretion by high-performance liquid chromatography with tandem mass spectrometry to evaluate their absolute bioavailability by taking into account all known and some unknown catabolites deriving from their interaction with the gastrointestinal tract and its host microflora. METHODS A feeding study was carried out in 20 healthy human volunteers who ingested 400 mL of a ready-to-drink green tea containing approximately 400 μmol of flavan-3-ols. Urine and plasma were collected for 4 and 24h, respectively, and 39 relevant catabolites were identified in these biological fluids by tandem mass spectrometry. RESULTS In biological fluids, 39 relevant flavan-3-ol catabolites were identified. In plasma, (-)-epigallocatechin-3-gallate was the only unmetabolized compound and the highest in absolute concentration compared with (-)-epigallocatechin and (-)-epicatechin conjugates. Colonic microflora-derived polyhydroxyphenyl-γ-valerolactones were by far the main urinary catabolites, averaging 10 times greater concentratin than flavan-3-ol conjugates. The calculated bioavailability was equal to 39% and it is interesting to notice the great variability in urinary excretion of colonic metabolites among participants, probably related to differences in their own colonic microflora. CONCLUSION This study demonstrates that green tea catechins are more bioavailable than previously observed when colonic ring fission metabolites are taken into consideration. Regular consumption of ready-to-drink green tea containing flavan-3-ols allows a non-marginal exposure of the human body to these catabolites, somehow justifying the numerous beneficial actions described as linked to green tea intake.

Gastric emptying of a solid meal is accelerated by the removal of dietary fibre naturally present in food.

Exogenous fibre added to liquid meals delays gastric emptying. Its effect on solid meals is uncertain, and nothing is known of the effect on gastric emptying of fibre naturally present in food. This study therefore looked at gastric emptying of two different solid meals in eight healthy subjects and their blood glucose responses. The meals were exactly equivalent except for the total dietary fibre content (high fibre 20 g, low fibre 4 g of dietary fibre per 1000 kcal) and supplied 870 kcal (700 kcal women), 47% of which was from carbohydrates, 36% from fats, and 17% from proteins. Ultrasonography was used to measure antral diameters before the meal (basal), immediately after it (time 0), and at 30, 60, 120, 180, 240, and 300 minutes. In addition, subjects filled in a questionnaire on their feelings of hunger, epigastric fullness, and satiety before the meal and at hourly intervals after it. Basal and maximal postprandial antral sections were similar for the two meals (basal section: 283.9 (29.5) v 340.9 (44.7) mm2 for the low and the high fibre meal, NS; maximal postprandial section: 1726 (101.9) v 1593 (120.4) mm2, NS). Total gastric emptying time was significantly reduced by fibre removal (186.0 (15.6) v 231.7 (17.3) minutes after the low and the high fibre meal, p < 0.05). Blood glucose was higher after the low fibre meal, and the area under the glycaemic curve significantly greater (226 (23.1) v 160 (20.0) mmol/min/dl-1, p < 0.05). No difference was found in satiety or fullness feelings, but hunger returned more rapidly after the low fibre meal. In conclusion, fibre naturally present in food delays gastric emptying of a solid meal, reduces the glycaemic response, and delays the return of hunger.

Dietary Glycemic Load and Index and Risk of Coronary Heart Disease in a Large Italian Cohort: The EPICOR Study

BACKGROUND Dietary glycemic load (GL) and glycemic index (GI) in relation to cardiovascular disease have been investigated in a few prospective studies with inconsistent results, particularly in men. The present EPICOR study investigated the association of GI and GL with coronary heart disease (CHD) in a large and heterogeneous cohort of Italian men and women originally recruited to the European Prospective Investigation into Cancer and Nutrition study. METHODS We studied 47 749 volunteers (15 171 men and 32 578 women) who completed a dietary questionnaire. Multivariate Cox proportional hazards modeling estimated adjusted relative risks (RRs) of CHD and 95% confidence intervals (CIs). RESULTS During a median of 7.9 years of follow-up, 463 CHD cases (158 women and 305 men) were identified. Women in the highest carbohydrate intake quartile had a significantly greater risk of CHD than did those in the lowest quartile (RR, 2.00; 95% CI, 1.16-3.43), with no association found in men (P = .04 for interaction). Increasing carbohydrate intake from high-GI foods was also significantly associated with greater risk of CHD in women (RR, 1.68; 95% CI, 1.02-2.75), whereas increasing the intake of low-GI carbohydrates was not. Women in the highest GL quartile had a significantly greater risk of CHD than did those in the lowest quartile (RR, 2.24; 95% CI, 1.26-3.98), with no significant association in men (P = .03 for interaction). CONCLUSION In this Italian cohort, high dietary GL and carbohydrate intake from high-GI foods increase the overall risk of CHD in women but not men.

Effects of different cooking methods on antioxidant profile, antioxidant capacity, and physical characteristics of artichoke.

In this study, the effects of three common cooking practices (i.e., boiling, steaming, and frying) on the artichoke phenolic compounds pattern were evaluated by LC-MS/MS analysis. The variation of carotenoids, antioxidant capacity, and artichoke physical properties after cooking was also investigated. The major phenolic compounds present in the raw sample were 5- O-caffeoylquinic and 1,5-di- O-caffeoylquinic acids; after cooking treatments, an increase of the overall caffeoylquinic acids concentration due to the formation of different dicaffeoylquinic acid isomers was observed. Steamed and fried samples showed similar patterns of dicaffeoylquinic concentrations, which were higher with respect to the boiled samples. On the other hand, all cooking practices, particularly frying, decreased flavonoid concentration. The antioxidant capacity of cooked artichokes, measured by three different assays, enormously increased after cooking, particularly after steaming (up to 15-fold) and boiling (up to 8-fold). The observed cooking effect on the artichoke antioxidant profile is probably due to matrix softening and increased extractability of compounds, but the increase of antioxidant capacity is much higher than the increase of antioxidant concentration. These results suggest that some common cooking treatments can be used to enhance the nutritional value of vegetables, increasing bioaccessibility of health-promoting constituents.

The effect of cooking on the phytochemical content of vegetables

Cooking induces many chemical and physical modifications in foods; among these the phytochemical content can change. Many authors have studied variations in vegetable nutrients after cooking, and great variability in the data has been reported. In this review more than 100 articles from indexed scientific journals were considered in order to assess the effect of cooking on different phytochemical classes. Changes in phytochemicals upon cooking may result from two opposite phenomena: (1) thermal degradation, which reduces their concentration, and (2) a matrix softening effect, which increases the extractability of phytochemicals, resulting in a higher concentration with respect to the raw material. The final effect of cooking on phytochemical concentration depends on the processing parameters, the structure of food matrix, and the chemical nature of the specific compound. Looking at the different cooking procedures it can be concluded that steaming will ensure better preservation/extraction yield of phenols and glucosinolates than do other cooking methods: steamed tissues are not in direct contact with the cooking material (water or oil) so leaching of soluble compounds into water is minimised and, at the same time, thermal degradation is limited. Carotenoids showed a different behaviour; a positive effect on extraction and the solubilisation of carotenes were reported after severe processing.