Slow Digestion Research Articles

Proximal composition and in vitro starch digestibility in flaxseed‐added corn tortilla

AbstractBACKGROUND: The effect of addition of flaxseed flour (10:90, 15:85 and 20:80, w/w) on the chemical composition and starch digestibility of corn tortilla was investigated. Tortillas were baked and frozen in liquid nitrogen, freeze‐dried, ground and analyzed for fat, protein, ash, total starch (TS), available starch (AS) and resistant starch (RS) contents as well as for starch hydrolysis rate and predicted glycemic index (pGI). Tortillas made from commercial nixtamalized corn flour were used as control sample.RESULTS: Flaxseed flour addition increased the fat and protein content of tortilla, whereas TS and AS decreased. TS was 15.25% lower in the 20% flaxseed‐containing tortilla as compared to the control sample. The AS content was 12.65% lower in the composite tortilla. RS content in the samples ranged between 1.92% for the control sample and 5.08% for the tortilla containing 20% flaxseed. The reduced enzymatic starch hydrolysis rate and pGI recorded for the flaxseed‐added tortilla, indicated slow digestion features.CONCLUSIONS: Flaxseed‐added tortilla might be used to increase the consumption of α‐linolenic acid in the daily diet and modulate starch digestibility of corn tortilla. This kind of product may be used by people with special diet reqirements. Copyright © 2008 Society of Chemical Industry

Insulin and Antidiabetic Drugs—Implications for the Perioperative Setting

ORAL ANTIDIABETIC agents for type 2 diabetes vary in their mechanisms of action, which include stimulation of insulin secretion, inhibition of hepatic glucose production, increased sensitivity to insulin, and slowed carbohydrate digestion and absorption from dietary oral intake (Table 1). Although oral hypoglycemic agents are commonly held on the morning of surgery, thiazolidinediones (eg, rosiglitazone, pioglitazone), are not associated with hypoglycemia. Although metformin (a biguanide) is not associated with hypoglycemia, several factors (eg, renal dysfunction, administration of iodinated contrast media) can increase the risk for the rare, but potentially fatal, adverse effect of lactic acidosis.

Effects of processing high amylose maize starches under controlled conditions on structural organisation and amylase digestibility

The amylase digestibility of high-amylose maize starches has been compared before and after thermo-mechanical processing. Starches were analysed for enzyme-resistant starch yield, apparent amylose content, crystallinity (X-ray diffraction), and molecular order (NMR and FTIR), both before and after treatment with α-amylase. All samples had significant (>10%) enzyme-resistant starch levels irrespective of the type and extent of thermal or enzymic processing. Molecular or crystalline order was not a pre-requisite for enzyme resistance. Near-amorphous forms of high amylose maize starches are likely to undergo recrystallisation during the enzyme-digestion process. The mechanism of enzyme resistance of granular high-amylose starches is found to be qualitatively different to that for processed high-amylose starches. For all samples, measured levels of enzyme resistance are due to the interruption of a slow digestion process, rather than the presence of completely indigestible material.

Efficiency of facultative frugivory in the nectar-feeding bat Glossophaga commissarisi: the quality of fruits as an alternative food source

The efficiency of food exploitation correlates positively with the extent of dietary specialization. Neotropical nectar-feeding bats (Glossophaginae) have one of the most specialized diets among mammals, as floral nectar constitutes a sugar-rich and highly digestible but protein and fiber depleted food source. However, dietary constraints, such as a temporary scarcity of nectar, or protein demands may sometimes require the uptake of alternative food items. We investigated the influence of a diet switch from nectar to fruit on intestinal morphology, body mass, and energy budget in the nectar-feeding bat Glossophaga commissarisi and quantified feeding efficiency. We hypothesized that these nectar specialists depend on a constant supply of nectar, if they were lacking the ability for morphological and physiological plasticity in response to a fiber-rich diet. Although capable of harvesting infructescences of Piper hispidum, G. commissarisi was less efficient in extracting energy from fruits (48% digestive efficiency of total fruit energy content) than from nectar (c. 99% digestive efficiency). The intestinal morphology and organ masses did not change after bats were switched from nectar to fruits. Captive bats exhibited lower daily energy expenditures and flight activity when feeding on fruits than during nectarivory. Possibly, this may have been a deliberate regulation to balance reduced feeding efficiency, or simply the consequence of extended digestive pauses. The low digestibility of Piper, in combination with slow digestion and the bats' inability for morphological and physiological plasticity may cause nectar-feeders to reduce their maximum energy expenditure when feeding on fruits. We argue that although fruits may substitute for nectar, they may cause restricted maximum energy assimilation compared with nectar.

PASTA ADDED WITH CHICKPEA FLOUR: CHEMICAL COMPOSITION, IN VITRO STARCH DIGESTIBILITY AND PREDICTED GLYCEMIC INDEXPASTA ADICIONADA CON HARINA DE GARBANZO: COMPOSICIÓN QUÍMICA, DIGESTIBILIDAD IN VITRO DEL ALMIDÓNY PREDICCIÓN DEL ÍNDICE GLUCÉMICO

Pasta was prepared with of durum wheat flour mixed with chickpea flour at two different levels and its chemical composition, in vitro starch digestibility and predicted glycemic index were assessed. Protein, ash, lipid, and dietary fiber content increased while total starch decreased with the chickpea flour level in the composite pasta, all in accordance to the composition of the legume flour. Potentially available starch decreased and resistant starch (RS) increased by adding chickpea flour to the pasta. The main indigestible starch component in composite spaghetti was the fiber-associated RS, representing up to 50 % of total RS levels. The starch hydrolysis index (HI) decreased as chickpea flour in the pasta increased, reflecting the slow and low digestion of the starch in the leguminous ingredient. Predicted glycemic index was lower in spaghetti added with chickpea flour than in durum wheat-control pasta. Pasta added with chickpea flour might be a dietetic alternative for people with low-calorie requirements. Resumen Se elaboró pasta mezclando sémola de trigo con harina de garbanzo a dos niveles y se evaluó su composición química, digestibilidad del almidón in vitro y se predijo el índice glucémico. El contenido de proteína, ceniza, lípidos y fibra dietética incrementó mientras que el almidón total disminuyó con el contenido de harina de garbanzo en la pasta, esto debido a la composición de la harina de la leguminosa. El contenido de almidón disponible disminuyó y el almidón resistente (AR) incrementó con la adición de la harina de garbanzo a la pasta. El principal componente del almidón no digestible en el espagueti con harina de garbanzo fue el AR asociado a fibra, que representó más del 50 % del AR total. El índice de hidrólisis (IH) del almidón disminuyó con el incrementó del nivel de harina de garbanzo en la pasta, reflejando la baja y lenta digestión del almidón de la leguminosa. La predicción del índice glucémico fue menor en el espagueti adicionado con harina de garbanzo que la muestra control. La pasta adicionada con harina de garbanzo puede ser una alternativa dietética para personas con bajos requerimientos calóricos. Palabras clave: Índice glucémico, composición química, pasta, garbanzo, almidón resistente, fibra dietética

Slowly Digestible State of Starch: Mechanism of Slow Digestion Property of Gelatinized Maize Starch

The mechanism underlying the previously reported parabolic relationship between amylopectin fine structure, represented by the weight ratio of linear short chains [degree of polymerization (DP < 13) to long chains (DP >/= 13], and slowly digestible starch (SDS) content was investigated from the viewpoint of starch retrogradation and substrate susceptibility to enzyme hydrolysis. A maize mutant sample, termed "highest long-chain starch" (HLCS) representing group I samples with a higher proportion of long chains, showed a bell-shaped SDS pattern with retrogradation time, whereas insignificant changes in SDS were found for the sample termed "highest short-chain starch" (HSCS) representing group II samples with a higher proportion of short chains. This corresponded to results from X-ray powder diffraction and differential scanning calorimetry that showed a rapid increase of crystallinity and enthalpy for HLCS during retrogradation, but negligible changes for sample HSCS. Therefore, retrogradation was associated with SDS content for group I samples, but not for group II samples. Analysis of amylopectin fine structure, SDS content, retrogradation enthalpy, SDS material debranching profile, and hydrolysis pattern demonstrated, for group I samples, that linear branched chains of DP 9-30 of amylopectin may act as anchor points to slow the digestion of branced-chain fractions of DP > 30, which constitute the major slowly digestible portion, whereas for group II samples, it is the inherent molecular structure of amylopectin with a higher amount of branches and shorter chains that is not favorable for rapid enzyme digestion. The concept of a slowly digestible starch state (SDS state) that could be a chemical or physical entity is proposed to better describe the mechanistic underpinning of the slow digestion property of starches.

Nutritional Property of Endosperm Starches from Maize Mutants: A Parabolic Relationship between Slowly Digestible Starch and Amylopectin Fine Structure

The relationship between the slow digestion property of cooked maize starch and its molecular fine structure was investigated. Results of the in vitro Englyst assay showed a range of rapidly digestible starch (RDS) (70.1-98.9%), slowly digestible starch (SDS) (0.2-20.3%), and resistant starch (RS) (0.0-13.7%) among the tested maize mutant flour samples. Further analysis showed that amylose content was significantly correlated ( R = 0.763, P < 0.001) with RS amount but not with that of SDS, indicating that amylopectin is the starch molecule associated with SDS. Total starch debranching analysis revealed a parabolic relationship between SDS content and the weight ratio of amylopectin short chains (DP < 13, named SF) to long chains (DP >/= 13, named LF), which means amylopectin with a higher amount of either short chains or long chains can produce relatively high amounts of SDS. Furthermore, debranching analysis of the SDS materials from samples with the highest and lowest weight ratios of SF/LF (both had a high amount SDS) showed significantly different profiles, indicating there is not a uniform molecular structure for SDS. Thus, genetic mutants of maize samples have a good potential to provide raw starch materials of high nutritional quality. An additional finding showed that a simple and comparably high-throughput technique of Rapid Visco-Analyzer (RVA) can be used to screen genetic mutants on the basis of their RVA profiles.

Determinação das frações de proteína e de carboidratos de gramíneas do gênero &lt;em&gt;Cynodon&lt;/em&gt; em idades ao corte

Three Cynodon grasses (Poaceae) (Tifton 85, Tifton 44 and Coast-cross) harvested at ages 21, 42 and 63 days in the summer were evaluated for protein and carbohydrate fractions composition. Crude protein was divided into 5 fractions: A (non-protein nitrogen), B1 (soluble protein with fast rumen degradability), B2 (insoluble protein with intermediate rumen degradability), B3 (insoluble protein with slow rumen degradability) and C (indigestible protein). Carbohydrates were divided into 3 fractions: A + B1 (fast and intermediate rumen digestibility), B2 (slow rumen digestibility) and C (indigestible fiber). Experimental design consisted of a split-plot (grasses as plots and cut age as sub-plots) with three repetitions. Cut age was analyzed by regression and models were chosen on the analysis of identity. There were no differences (p> 0,05) among grasses with regard to protein and carbohydrate fractions composition. C fraction of protein showed linear increase (p < 0.05) with cut age, ranging from 22.77 to 25.79%. A + B1 fraction decreased (p < 0.05) from 16.27 to 7.03% and B2 and C fractions increased (p < 0.05) from 76.86 to 79.42% and 6.83 to 13.55%, respectively, between cuts at 21 and 63 days old.

Effect of Structural and Physicochemical Characteristics of the Protein Matrix in Pasta on In Vitro Starch Digestibility

Pasta is a popular carbohydrate-based food with a low glycemic response. A continuous protein matrix which entraps starch granules and/or limits/retards starch hydrolysis by α-amylase is thought to be an important factor in explaining the slow digestion of starch in pasta. The characteristics of the protein matrix may also play an important role in determining the rate of starch digestion in pasta and therefore its glycemic response. In this study, the structural and physicochemical characteristics of the protein matrix of pasta were modified by varying the number of passes through sheeting rollers to investigate their effect on in vitro starch digestibility. The results show that the proteins dissociated from the starch granules with increasing sheeting passes thereby allowing an increased degree of digestion of starch.

Costs of group size: lower developmental and reproductive rates in larger groups of leaf monkeys

Feeding competition is suggested as a major factor constraining group size in social foragers. It has, however, been challenging to demonstrate consequences of reduced energy gain in terms of fitness, possibly because social foragers may compensate negative effects of scramble competition via adjustments in time budgets. Herbivorous animals are particularly interesting in this context because their fibrous diet and slow digestion process may make it difficult to adjust time budgets. Here we investigate infant development and reproductive rates in Phayre’s leaf monkeys (Trachypithecus phayrei) at Phu Khieo Wildlife Sanctuary, Thailand. The diet of the species consists of 39.0% leaves (maximum 81.2% per month). Our analysis is based on data for 3 groups (185 group months) of different sizes (mean 11.4, 18.3, and 25.8 individuals, respectively). Infant development was significantly slower in the large group, in which infants changed to the adult coat later than in the medium-sized group (20.3 vs. 26.3 weeks) and were older when weaned (18.3, 19.7, and 21.4 months, respectively). The interbirth interval after a surviving infant significantly increased with group size (21.3, 22.8, and 24.5 months) while rearing success did not differ (77.8%, 76.5%, and 82.4%, survival to 2 years). Thus, infants in the large group developed more slowly were weaned later and females reproduced more slowly. With similar infant survival rates, these different reproductive rates indicate fitness differences across groups. As in other herbivores, these group-specific differences may reflect scramble competition for food or differences in habitat quality. Key words: infant development, infant mortality, interbirth interval, reproductive costs, scramble competition, Trachypithecus phayrei. [Behav Ecol]

Slowly Digestible Waxy Maize Starch Prepared by Octenyl Succinic Anhydride Esterification and Heat−Moisture Treatment: Glycemic Response and Mechanism

The mechanism and molecular structure of the slowly digestible waxy maize starch prepared by octenyl succinic anhydride (OSA) esterification and heat-moisture treatment were investigated. The in vitro Englyst test showed a proportion of 28.3% slowly digestible starch (SDS) when waxy maize starch was esterified with 3% OSA (starch weight based, and it is named OSA-starch), and a highest SDS content of 42.8% was obtained after OSA-starch (10% moisture) was further heated at 120 degrees C for 4 h (named HOSA-starch). The in vivo glycemic response of HOSA-starch, which showed a delayed appearance of blood glucose peak and a significant reduction (32.2%) of the peak glucose concentration, further confirmed its slow digestion property. Amylopectin debranching analysis revealed HOSA-starch had the highest resistance to debranching enzymes of isoamylase and pullulanase, and a simultaneous decrease of K m and V m (enzyme kinetics) was also shown when HOSA-starch was digested by either alpha-amylase or amyloglucosidase, indicating that the slow digestion of HOSA-starch resulted from an uncompetitive inhibition of enzyme activity during digestion. Size exclusion chromatography analysis of HOSA-starch showed fragmented amylopectin molecules with more nonreducing ends that are favorable for RS conversion to SDS by the action of amyloglucosidase in the Englyst test. Further solubility analysis indicates that the water-insolubility of HOSA-starch is caused by OSA-mediated cross-linking of amylopectin and the hydrophobic interaction between OSA-modified starch molecules. The water-insolubility of HOSA-starch would decrease its enzyme accessibility, and the digestion products with attached OSA molecules might also directly act as the uncompetitive inhibitor to reduce the enzyme activity leading to a slow digestion of HOSA-starch.

Prevalence, Incidence Estimation, Risk Factors and Characterization of Chronic Prostatitis/Chronic Pelvic Pain Syndrome in Urological Hospital Outpatients in Italy: Results of a Multicenter Case-Control Observational Study

We evaluated the prevalence and estimated the incidence and risk factors of chronic prostatitis/chronic pelvic pain syndrome in urological hospital outpatients in Italy. From January to June 2006 patients from 28 Italian urological centers who were between 25 and 50 years old with symptoms of chronic prostatitis/chronic pelvic pain syndrome were consecutively enrolled in this prospective epidemiological case-control study. A total of 152 subjects of similar age, race and area of origin who were investigated for infertile couples but were otherwise healthy served as controls. All subjects provided a medical history and underwent different symptom scorings, clinical evaluation and microbiological tests. Of 5,540 male urological outpatients 764 with chronic prostatitis/chronic pelvic pain syndrome were enrolled, including 225 (29.4%) at the first presentation and 539 (70.6%) who underwent previous treatment. Thus, the prevalence of the syndrome was 13.8%, while the estimated incidence was 4.5%. Cigarette smoking, a high caloric diet with low fruit and vegetable consumption, constipation, meteorism, slow digestion, a sexual relationship with more than 1 partner and coitus interruptus were more likely in patients with chronic prostatitis/chronic pelvic pain syndrome than in controls (each p <0.001). The syndrome had a negative influence on sexual desire, erectile dysfunction and premature ejaculation (p <0.001). The Meares and Stamey test was positive in 13.3% of patients and in 2.9% of controls. Urethral swabs in patients with a negative Meares and Stamey test were positive for sexually transmitted pathogens in 6%. The prevalence and estimated incidence of chronic prostatitis/chronic pelvic pain syndrome in urological hospital outpatients in Italy are high. The syndrome is closely related to lifestyle, diet, smoking, gastrointestinal or anorectal disease and impaired sexual function.

Alternative Use of Chickpea Flour in Breadmaking: Chemical Composition and Starch Digestibility of Bread

Chickpea flour (CF) was prepared and used as an ingredient for elaboration of bread with different levels of wheat versus CFs (80 : 20 and 60: 40). Available starch (AS), resistant starch (RS), dietary fibre (DF), the in vitro starch hydrolysis indices (HIs), using a chewing/dialysis digestion protocol and the acceptability of the experimental bread were compared with those of a control bread prepared with wheat flour and baked in the laboratory. HIs were used to predict glyceamic indices (pGI). The bread analysed did not show differences in moisture, lipids and ash content, but CF-bread had higher protein, RS and DF amount than control bread. HI-based pGI for the CF-bread were 46.92 and 34.67%, which were significantly lower than control bread (65.31%), suggesting a `slow carbohydrate' feature for the CF-based goods. The slow digestion characteristics of chickpea are largely retained in the experimental bread. Data support the perceived health beneficial properties of legumes and CF might be used as a potential ingredient for bakery products with slowly digestible carbohydrates.

Starch with a Slow Digestion Property Produced by Altering Its Chain Length, Branch Density, and Crystalline Structure

The hypothesis of increasing the branch density of starch to reduce its digestion rate through partial shortening of amylopectin exterior chains and the length of amylose was investigated. Starch products prepared using beta-amylase, beta-amylase and transglucosidase, maltogenic alpha-amylase, and maltogenic alpha-amylase and transglucosidase showed significant reduction of rapidly digested starch by 14.5%, 29.0%, 19.8%, and 31.0% with a concomitant increase of slowly digested starch by 9.0%, 19.7%, 5.7%, and 11.0%, respectively. The resistant starch content increased from 5.1% to 13.5% in treated starches. The total contents of the prebiotics isomaltose, isomaltotriose, and panose (Isomaltooligosaccharides) were 2.3% and 5.5%, respectively, for beta-amylase/transglucosidase- and maltogenic alpha-amylase/transglucosidase-treated starches. The molecular weight distribution of enzyme-treated starches and their debranched chain length distributions, analyzed using high-performance size-exclusion chromatography with multiangle laser light scattering and refractive index detection (HPSEC-MALLS-RI) and HPSEC-RI, showed distinctly different patterns among starches with different enzyme treatments. A larger proportion of low molecular weight fractions appeared in starches treated additionally with transglucosidase. All enzyme-treated starches showed a mixture of B- and V-type X-ray diffraction patterns, and 1H NMR spectra showed a significant increase of alpha-1,6 linkages. Both the increase of the starch branch density and the crystalline structure in the treated starches likely contribute to their slow digestion property.

Slowly digestible starch – its structure and health implications: a review

Starch is the main carbohydrate in human nutrition and offers a range of desired technological properties. The nutritional quality of starch strongly depends on starch structure and on its processing. Starch digestibility in the human small intestine can vary from a rapid digestion to indigestibility. However, the structural properties of the intermediate fraction of starch with slow digestibility and its potential health benefits are not well understood. The present review highlights current knowledge on starch structures causing a slow digestibility and explores their health implications.

Composition and effect of soaking on starch digestibility of Phaseolus vulgaris (L.) cv. ‘Mayocoba’

SummaryCommon beans from Mayocoba variety were soaked in different solutions, cooked, stored and evaluated for cooking time, chemical composition and in vitro starch digestibility. Soaking decreased cooking time; the lowest value (149 min) was obtained when a sodium chloride (1%) and sodium bicarbonate (0.75%) mixture was used. Total starch content in samples soaked in water, sodium chloride or sodium bicarbonate increased in relation to the non‐soaked sample, a pattern that may be associated with lixiviation of other bean components, which leads to increased TS content. Soaking also affected available starch (AS) levels, because beans soaked in sodium bicarbonate solution exhibited the lowest AS; on the contrary, beans soaked in water and sodium chloride showed higher AS contents than non‐soaked beans. In agreement with AS content, beans soaked in bicarbonate solution presented the highest resistant starch values. Soaking in diverse solutions did not affect the hydrolysis index and consequently the predicted glycaemic index(pGI). pGIs of Mayocoba beans reiterate the well‐known beneficial ‘slow digestion’ features of starch in pulses.

Physicochemical properties of amylose-free and high-amylose starches from transgenic sweetpotatoes modified by RNA interference

The transgenic sweetpotatoes having amylose-free and moderately high-amylose starches have been obtained by RNA interferences of granule-bound starch synthase I (GBSSI) and starch branching enzyme II [SBEII (class A)] genes, respectively. In this study, the physicochemical properties of such sweetpotato starches were investigated. From the amylose-free starches, structural changes in the starch molecules were found by suppressing GBSSI expression: lack of amylose, lack of long chains with more than DP 100 in amylopectin, and a slight decrease in chains with DP 6 and 7 in amylopectin. These results suggest that GBSSI participates in not only the synthesis of amylose molecules, but also the characterization of amylopectin molecules. In the case of the high-amylose starches, complicated structural changes were found by suppressing SBEII expression: increase in amylose, increase in phosphate content, alteration of crystalline structure, decrease in long chains with more than DP 100 in amylopectin, decrease in chains around DP 6–11, and increase in chains around DP 12–15 and DP 24–33 in amylopectin. As the results of the structural changes, the amylose-free sweetpotato starches showed a very slow retrogradation and high digestibility by pancreatin, whereas the high-amylose sweetpotato starches showed a higher pasting viscosity, more rapid retrogradation and lower digestibility compared to normal starch.

Structural Basis for the Slow Digestion Property of Native Cereal Starches

Native cereal starches are ideal slowly digestible starches (SDS), and the structural basis for their slow digestion property was investigated. The shape, size, surface pores and channels, and degree of crystallinity of starch granules were not related to the proportion of SDS, while semicrystalline structure was critical to the slow digestion property as evidenced by loss of SDS after cooking. The high proportion of SDS in cereal starches, as compared to potato starch, was related to their A-type crystalline structure with a lower degree of perfection as indicated by a higher amount of shortest A chains with a degree of polymerization (DP) of 5-10. The A-type amorphous lamellae, an important component of crystalline regions of native cereal starches, also affect the amount of SDS as shown by a reduction of SDS in lintnerized maize starches. These observations demonstrate that the supramolecular A-type crystalline structure, including the distribution and perfection of crystalline regions (both crystalline and amorphous lamellae), determines the slow digestion property of native cereal starches.

Slow Digestion Property of Native Cereal Starches

The slow digestion property of native cereal starches, represented by normal maize starch, was investigated. The in vitro Englyst test showed that 53.0% of the maize starch is slowly digestible starch (SDS), and scanning electron microscopy (SEM) revealed that SDS starts from an increase of pore size until almost complete fragmentation of starch granules. However, similar amounts of SDS ( approximately 50%) were shown for partially digested fragmented starch residuals, which would normally be considered resistant to digestion based on the Englyst assay. Molecularly, both amylopectin (AP) and amylose (AM) contributed to the amount of SDS as evidenced by a similar ratio of AP to AM at different digestion times. Consistently, similar degrees of crystallinity, comparable gelatinization behavior, and similar debranched profiles of starch residuals following different digestion times indicated that the crystalline and amorphous regions of starch granules were evenly digested through a mechanism of side-by-side digestion of concentric layers of semicrystalline shells of native starch granules.

Feeding and digestion in low salinity in an osmoconforming crab, Cancer gracilis II. Gastric evacuation and motility

Gastric evacuation and gut contraction rates were followed in the graceful crab Cancer gracilis during exposure to low salinity. Crabs were fed a radio-opaque meal and then exposed to 100% seawater (SW), 80%SW or 60%SW; passage of digesta was followed using a fluoroscope. Exposure to low salinity increased the time for food passage through the gut system. Times for emptying of the foregut, midgut and hindgut varied in a dose-dependent manner. In the lowest salinity, crabs regurgitated food from the foregut after approximately 6 h. This may act as a protective response, clearing the gut and avoiding subsequent increases in metabolism associated with digestion. Contraction rate of the cardiac stomach and gastric mill was sporadic and there was no significant change with salinity. In contrast, contractions of the pyloric region were more constant and rapid. Pyloric contractions decreased at each salinity within 2-4 h after feeding. Contraction rates of the pyloric chamber were significantly lower in 60%SW compared with 100%SW and 80%SW. During a salinity cycle there was also slowing of gut contractions and food passage through the gut system. Pre-treatment levels were only regained slowly when the animals were returned to 100%SW. Cancer gracilis was able to slow digestion during low salinity exposure, which may spare resources for other systems. However, the crabs could not halt digestion completely and may be committed to protein synthesis once intracellular digestion has begun.